fix: abort copy styles action when pressing esc

This shows the time in different timezones

Cargo.lock

@@ -43,6 +43,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "approx"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cab112f0a86d568ea0e627cc1d6be74a1e9cd55214684db5561995f6dad897c6"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "arrayvec"
 version = "0.7.6"
@@ -414,7 +423,7 @@ dependencies = [
 
 [[package]]
 name = "ironcalc"
-version = "0.5.0"
+version = "0.6.0"
 dependencies = [
  "bitcode",
  "chrono",
@@ -430,7 +439,7 @@ dependencies = [
 
 [[package]]
 name = "ironcalc_base"
-version = "0.5.0"
+version = "0.6.0"
 dependencies = [
  "bitcode",
  "chrono",
@@ -443,11 +452,12 @@ dependencies = [
  "ryu",
  "serde",
  "serde_json",
+ "statrs",
 ]
 
 [[package]]
 name = "ironcalc_nodejs"
-version = "0.5.0"
+version = "0.6.0"
 dependencies = [
  "ironcalc",
  "napi",
@@ -782,7 +792,7 @@ dependencies = [
 
 [[package]]
 name = "pyroncalc"
-version = "0.5.7"
+version = "0.6.0"
 dependencies = [
  "bitcode",
  "ironcalc",
@@ -965,6 +975,16 @@ version = "0.3.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "38b58827f4464d87d377d175e90bf58eb00fd8716ff0a62f80356b5e61555d0d"
 
+[[package]]
+name = "statrs"
+version = "0.18.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a3fe7c28c6512e766b0874335db33c94ad7b8f9054228ae1c2abd47ce7d335e"
+dependencies = [
+ "approx",
+ "num-traits",
+]
+
 [[package]]
 name = "subtle"
 version = "2.5.0"
@@ -1075,7 +1095,7 @@ checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
 [[package]]
 name = "wasm"
-version = "0.5.0"
+version = "0.6.0"
 dependencies = [
  "ironcalc_base",
  "serde",

Dockerfile

@@ -0,0 +1,93 @@
+FROM rust:latest AS builder
+
+WORKDIR /app
+COPY . .
+
+# Tools + wasm toolchain + Node via nvm
+RUN apt-get update && apt-get install -y --no-install-recommends \
+      bash curl ca-certificates make \
+    && rustup target add wasm32-unknown-unknown \
+    && cargo install wasm-pack \
+    && bash -lc "curl -fsSL https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh | bash -" \
+    && bash -lc '\
+         export NVM_DIR="$HOME/.nvm" && \
+         source "$NVM_DIR/nvm.sh" && \
+         nvm install 22 && nvm alias default 22 && \
+         nroot="$NVM_DIR/versions/node/$(nvm version default)/bin" && \
+         ln -sf "$nroot/node" /usr/local/bin/node && \
+         ln -sf "$nroot/npm"  /usr/local/bin/npm  && \
+         ln -sf "$nroot/npx"  /usr/local/bin/npx \
+       ' \
+    && npm install typescript \
+    && rm -rf /var/lib/apt/lists/*
+
+# build the server
+RUN cargo build --release --manifest-path webapp/app.ironcalc.com/server/Cargo.toml
+
+# build the wasm
+RUN make -C bindings/wasm
+
+# build the widget
+WORKDIR /app/webapp/IronCalc
+RUN npm install && npm run build
+
+# build the frontend app
+WORKDIR /app/webapp/app.ironcalc.com/frontend
+RUN npm install && npm run build
+
+# build the xlsx_2_icalc binary (we don't need the release version here)
+WORKDIR /app/xlsx
+RUN cargo build
+
+WORKDIR /app
+# copy the artifacts to a dist/ directory
+RUN mkdir dist
+RUN mkdir dist/frontend
+RUN cp -r webapp/app.ironcalc.com/frontend/dist/* dist/frontend/
+RUN mkdir dist/server
+RUN cp webapp/app.ironcalc.com/server/target/release/ironcalc_server dist/server/
+RUN cp webapp/app.ironcalc.com/server/Rocket.toml dist/server/
+RUN cp webapp/app.ironcalc.com/server/ironcalc.sqlite dist/server/
+
+# Create ic files in docs
+RUN mkdir -p dist/frontend/models
+
+# Loop over all xlsx files in xlsx/tests/docs & templates and convert them to .ic
+RUN bash -lc 'set -euo pipefail; \
+  mkdir -p dist/frontend/models; \
+  shopt -s nullglob; \
+  for xlsx_file in xlsx/tests/docs/*.xlsx; do \
+    base_name="${xlsx_file##*/}"; base_name="${base_name%.xlsx}"; \
+    ./target/debug/xlsx_2_icalc "$xlsx_file" "dist/frontend/models/${base_name}.ic"; \
+  done; \
+  for xlsx_file in xlsx/tests/templates/*.xlsx; do \
+    base_name="${xlsx_file##*/}"; base_name="${base_name%.xlsx}"; \
+    ./target/debug/xlsx_2_icalc "$xlsx_file" "dist/frontend/models/${base_name}.ic"; \
+  done'
+
+# ---------- server runtime ----------
+FROM debian:bookworm-slim AS server-runtime
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates && \
+    rm -rf /var/lib/apt/lists/*
+WORKDIR /app
+# Copy EVERYTHING you put in dist/server (binary + Rocket.toml + DB)
+COPY --from=builder /app/dist/server/ ./
+# Make sure Rocket binds to the container IP; explicitly point to the config file
+ENV ROCKET_ADDRESS=0.0.0.0 \
+    ROCKET_PORT=8000 \
+    ROCKET_CONFIG=/app/Rocket.toml
+EXPOSE 8000
+# Run from /app so relative paths in Rocket.toml/DB work
+CMD ["./ironcalc_server"]
+
+# ---------- caddy runtime (serves frontend + reverse-proxy /api) ----------
+FROM caddy:latest AS caddy-runtime
+
+WORKDIR /srv
+
+# Copy the frontend build output to /srv
+COPY --from=builder /app/dist/frontend/ /srv/
+
+# Copy the Caddyfile
+COPY --from=builder /app/webapp/app.ironcalc.com/Caddyfile.compose /etc/caddy/Caddyfile
+

README.md

@@ -31,7 +31,17 @@ This repository contains the main engine and the xlsx reader and writer.
 
 Programmed in Rust, you will be able to use it from a variety of programming languages like Python, JavaScript (wasm), nodejs and possibly R, Julia or Go.
 
-We will build different _skins_: in the terminal, as a desktop application or use it in you own web application.
+We will build different _skins_: in the terminal, as a desktop application or use it in your own web application.
+
+# Docker
+
+If you have docker installed just run:
+
+```bash
+docker compose up --build
+```
+
+head over to <http://localhost:2080> to test the application.
 
 # Building
 

base/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ironcalc_base"
-version = "0.5.0"
+version = "0.6.0"
 authors = ["Nicolás Hatcher <nicolas@theuniverse.today>"]
 edition = "2021"
 homepage = "https://www.ironcalc.com"
@@ -19,6 +19,7 @@ regex = { version = "1.0", optional = true}
 regex-lite = { version = "0.1.6", optional = true}
 bitcode = "0.6.3"
 csv = "1.3.0"
+statrs = { version = "0.18.0", default-features = false, features = [] }
 
 [features]
 default = ["use_regex_full"]

base/src/cast.rs

@@ -5,6 +5,7 @@ use crate::{
         token::Error,
         types::CellReferenceIndex,
     },
+    formatter::format::parse_formatted_number,
     model::Model,
 };
 
@@ -14,6 +15,23 @@ pub(crate) enum NumberOrArray {
 }
 
 impl Model {
+    pub(crate) fn cast_number(&self, s: &str) -> Option<f64> {
+        match s.trim().parse::<f64>() {
+            Ok(f) => Some(f),
+            _ => {
+                let currency = &self.locale.currency.symbol;
+                let mut currencies = vec!["$", "€"];
+                if !currencies.iter().any(|e| *e == currency) {
+                    currencies.push(currency);
+                }
+                // Try to parse as a formatted number (e.g., dates, currencies, percentages)
+                if let Ok((v, _number_format)) = parse_formatted_number(s, &currencies) {
+                    return Some(v);
+                }
+                None
+            }
+        }
+    }
     pub(crate) fn get_number_or_array(
         &mut self,
         node: &Node,
@@ -21,9 +39,9 @@ impl Model {
     ) -> Result<NumberOrArray, CalcResult> {
         match self.evaluate_node_in_context(node, cell) {
             CalcResult::Number(f) => Ok(NumberOrArray::Number(f)),
-            CalcResult::String(s) => match s.parse::<f64>() {
-                Ok(f) => Ok(NumberOrArray::Number(f)),
-                _ => Err(CalcResult::new_error(
+            CalcResult::String(s) => match self.cast_number(&s) {
+                Some(f) => Ok(NumberOrArray::Number(f)),
+                None => Err(CalcResult::new_error(
                     Error::VALUE,
                     cell,
                     "Expecting number".to_string(),
@@ -89,16 +107,16 @@ impl Model {
         self.cast_to_number(result, cell)
     }
 
-    fn cast_to_number(
+    pub(crate) fn cast_to_number(
         &mut self,
         result: CalcResult,
         cell: CellReferenceIndex,
     ) -> Result<f64, CalcResult> {
         match result {
             CalcResult::Number(f) => Ok(f),
-            CalcResult::String(s) => match s.parse::<f64>() {
-                Ok(f) => Ok(f),
-                _ => Err(CalcResult::new_error(
+            CalcResult::String(s) => match self.cast_number(&s) {
+                Some(f) => Ok(f),
+                None => Err(CalcResult::new_error(
                     Error::VALUE,
                     cell,
                     "Expecting number".to_string(),

base/src/constants.rs

@@ -12,6 +12,9 @@ pub(crate) const DEFAULT_WINDOW_WIDTH: i64 = 800;
 pub(crate) const LAST_COLUMN: i32 = 16_384;
 pub(crate) const LAST_ROW: i32 = 1_048_576;
 
+// Excel uses 15 significant digits of precision for all numeric calculations.
+pub(crate) const EXCEL_PRECISION: usize = 15;
+
 // 693_594 is computed as:
 // NaiveDate::from_ymd(1900, 1, 1).num_days_from_ce() - 2
 // The 2 days offset is because of Excel 1900 bug

base/src/expressions/parser/mod.rs

@@ -471,6 +471,20 @@ impl Parser {
             Node::NumberKind(s) => ArrayNode::Number(s),
             Node::StringKind(s) => ArrayNode::String(s),
             Node::ErrorKind(kind) => ArrayNode::Error(kind),
+            Node::UnaryKind {
+                kind: OpUnary::Minus,
+                right,
+            } => {
+                if let Node::NumberKind(n) = *right {
+                    ArrayNode::Number(-n)
+                } else {
+                    return Err(Node::ParseErrorKind {
+                        formula: self.lexer.get_formula(),
+                        message: "Invalid value in array".to_string(),
+                        position: self.lexer.get_position() as usize,
+                    });
+                }
+            }
             error @ Node::ParseErrorKind { .. } => return Err(error),
             _ => {
                 return Err(Node::ParseErrorKind {
@@ -490,6 +504,20 @@ impl Parser {
                 Node::NumberKind(s) => ArrayNode::Number(s),
                 Node::StringKind(s) => ArrayNode::String(s),
                 Node::ErrorKind(kind) => ArrayNode::Error(kind),
+                Node::UnaryKind {
+                    kind: OpUnary::Minus,
+                    right,
+                } => {
+                    if let Node::NumberKind(n) = *right {
+                        ArrayNode::Number(-n)
+                    } else {
+                        return Err(Node::ParseErrorKind {
+                            formula: self.lexer.get_formula(),
+                            message: "Invalid value in array".to_string(),
+                            position: self.lexer.get_position() as usize,
+                        });
+                    }
+                }
                 error @ Node::ParseErrorKind { .. } => return Err(error),
                 _ => {
                     return Err(Node::ParseErrorKind {

base/src/expressions/parser/static_analysis.rs

@@ -341,7 +341,8 @@ fn static_analysis_offset(args: &[Node]) -> StaticResult {
         }
         _ => return StaticResult::Unknown,
     };
-    StaticResult::Unknown
+    // Both height and width are explicitly 1, so OFFSET will return a single cell
+    StaticResult::Scalar
 }
 
 // fn static_analysis_choose(_args: &[Node]) -> StaticResult {
@@ -575,6 +576,37 @@ fn args_signature_xnpv(arg_count: usize) -> Vec<Signature> {
     }
 }
 
+// NETWORKDAYS(start_date, end_date, [holidays])
+// Parameters: start_date (scalar), end_date (scalar), holidays (optional vector)
+fn args_signature_networkdays(arg_count: usize) -> Vec<Signature> {
+    if arg_count == 2 {
+        vec![Signature::Scalar, Signature::Scalar]
+    } else if arg_count == 3 {
+        vec![Signature::Scalar, Signature::Scalar, Signature::Vector]
+    } else {
+        vec![Signature::Error; arg_count]
+    }
+}
+
+// NETWORKDAYS.INTL(start_date, end_date, [weekend], [holidays])
+// Parameters: start_date (scalar), end_date (scalar), weekend (optional scalar), holidays (optional vector)
+fn args_signature_networkdays_intl(arg_count: usize) -> Vec<Signature> {
+    if arg_count == 2 {
+        vec![Signature::Scalar, Signature::Scalar]
+    } else if arg_count == 3 {
+        vec![Signature::Scalar, Signature::Scalar, Signature::Scalar]
+    } else if arg_count == 4 {
+        vec![
+            Signature::Scalar,
+            Signature::Scalar,
+            Signature::Scalar,
+            Signature::Vector,
+        ]
+    } else {
+        vec![Signature::Error; arg_count]
+    }
+}
+
 // FIXME: This is terrible duplications of efforts. We use the signature in at least three different places:
 // 1. When computing the function
 // 2. Checking the arguments to see if we need to insert the implicit intersection operator
@@ -679,6 +711,7 @@ fn get_function_args_signature(kind: &Function, arg_count: usize) -> Vec<Signatu
         Function::Value => args_signature_scalars(arg_count, 1, 0),
         Function::Valuetotext => args_signature_scalars(arg_count, 1, 1),
         Function::Average => vec![Signature::Vector; arg_count],
+        Function::Avedev => vec![Signature::Vector; arg_count],
         Function::Averagea => vec![Signature::Vector; arg_count],
         Function::Averageif => args_signature_sumif(arg_count),
         Function::Averageifs => vec![Signature::Vector; arg_count],
@@ -690,13 +723,28 @@ fn get_function_args_signature(kind: &Function, arg_count: usize) -> Vec<Signatu
         Function::Maxifs => vec![Signature::Vector; arg_count],
         Function::Minifs => vec![Signature::Vector; arg_count],
         Function::Date => args_signature_scalars(arg_count, 3, 0),
+        Function::Datedif => args_signature_scalars(arg_count, 3, 0),
+        Function::Datevalue => args_signature_scalars(arg_count, 1, 0),
         Function::Day => args_signature_scalars(arg_count, 1, 0),
         Function::Edate => args_signature_scalars(arg_count, 2, 0),
         Function::Eomonth => args_signature_scalars(arg_count, 2, 0),
         Function::Month => args_signature_scalars(arg_count, 1, 0),
+        Function::Time => args_signature_scalars(arg_count, 3, 0),
+        Function::Timevalue => args_signature_scalars(arg_count, 1, 0),
+        Function::Hour => args_signature_scalars(arg_count, 1, 0),
+        Function::Minute => args_signature_scalars(arg_count, 1, 0),
+        Function::Second => args_signature_scalars(arg_count, 1, 0),
         Function::Now => args_signature_no_args(arg_count),
         Function::Today => args_signature_no_args(arg_count),
         Function::Year => args_signature_scalars(arg_count, 1, 0),
+        Function::Days => args_signature_scalars(arg_count, 2, 0),
+        Function::Days360 => args_signature_scalars(arg_count, 2, 1),
+        Function::Weekday => args_signature_scalars(arg_count, 1, 1),
+        Function::Weeknum => args_signature_scalars(arg_count, 1, 1),
+        Function::Workday => args_signature_scalars(arg_count, 2, 1),
+        Function::WorkdayIntl => args_signature_scalars(arg_count, 2, 2),
+        Function::Yearfrac => args_signature_scalars(arg_count, 2, 1),
+        Function::Isoweeknum => args_signature_scalars(arg_count, 1, 0),
         Function::Cumipmt => args_signature_scalars(arg_count, 6, 0),
         Function::Cumprinc => args_signature_scalars(arg_count, 6, 0),
         Function::Db => args_signature_scalars(arg_count, 4, 1),
@@ -785,6 +833,180 @@ fn get_function_args_signature(kind: &Function, arg_count: usize) -> Vec<Signatu
         Function::Formulatext => args_signature_scalars(arg_count, 1, 0),
         Function::Unicode => args_signature_scalars(arg_count, 1, 0),
         Function::Geomean => vec![Signature::Vector; arg_count],
+        Function::Networkdays => args_signature_networkdays(arg_count),
+        Function::NetworkdaysIntl => args_signature_networkdays_intl(arg_count),
+        Function::Acot => args_signature_scalars(arg_count, 1, 0),
+        Function::Acoth => args_signature_scalars(arg_count, 1, 0),
+        Function::Cot => args_signature_scalars(arg_count, 1, 0),
+        Function::Coth => args_signature_scalars(arg_count, 1, 0),
+        Function::Csc => args_signature_scalars(arg_count, 1, 0),
+        Function::Csch => args_signature_scalars(arg_count, 1, 0),
+        Function::Sec => args_signature_scalars(arg_count, 1, 0),
+        Function::Sech => args_signature_scalars(arg_count, 1, 0),
+        Function::Exp => args_signature_scalars(arg_count, 1, 0),
+        Function::Fact => args_signature_scalars(arg_count, 1, 0),
+        Function::Factdouble => args_signature_scalars(arg_count, 1, 0),
+        Function::Sign => args_signature_scalars(arg_count, 1, 0),
+        Function::Radians => args_signature_scalars(arg_count, 1, 0),
+        Function::Degrees => args_signature_scalars(arg_count, 1, 0),
+        Function::Int => args_signature_scalars(arg_count, 1, 0),
+        Function::Even => args_signature_scalars(arg_count, 1, 0),
+        Function::Odd => args_signature_scalars(arg_count, 1, 0),
+        Function::Ceiling => args_signature_scalars(arg_count, 2, 0),
+        Function::CeilingMath => args_signature_scalars(arg_count, 1, 2),
+        Function::CeilingPrecise => args_signature_scalars(arg_count, 1, 1),
+        Function::Floor => args_signature_scalars(arg_count, 2, 0),
+        Function::FloorMath => args_signature_scalars(arg_count, 1, 2),
+        Function::FloorPrecise => args_signature_scalars(arg_count, 1, 1),
+        Function::IsoCeiling => args_signature_scalars(arg_count, 1, 1),
+        Function::Mod => args_signature_scalars(arg_count, 2, 0),
+        Function::Quotient => args_signature_scalars(arg_count, 2, 0),
+        Function::Mround => args_signature_scalars(arg_count, 2, 0),
+        Function::Trunc => args_signature_scalars(arg_count, 1, 1),
+        Function::Gcd => vec![Signature::Vector; arg_count],
+        Function::Lcm => vec![Signature::Vector; arg_count],
+        Function::Base => args_signature_scalars(arg_count, 2, 1),
+        Function::Decimal => args_signature_scalars(arg_count, 2, 0),
+        Function::Roman => args_signature_scalars(arg_count, 1, 1),
+        Function::Arabic => args_signature_scalars(arg_count, 1, 0),
+        Function::Combin => args_signature_scalars(arg_count, 2, 0),
+        Function::Combina => args_signature_scalars(arg_count, 2, 0),
+        Function::Sumsq => vec![Signature::Vector; arg_count],
+        Function::N => args_signature_scalars(arg_count, 1, 0),
+        Function::Sheets => args_signature_scalars(arg_count, 0, 1),
+        Function::Cell => args_signature_scalars(arg_count, 1, 1),
+        Function::Info => args_signature_scalars(arg_count, 1, 1),
+        Function::Daverage => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dcount => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dget => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dmax => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dmin => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dsum => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dcounta => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dproduct => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dstdev => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dvar => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dvarp => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::Dstdevp => vec![Signature::Vector, Signature::Scalar, Signature::Vector],
+        Function::BetaDist => args_signature_scalars(arg_count, 4, 2),
+        Function::BetaInv => args_signature_scalars(arg_count, 3, 2),
+        Function::BinomDist => args_signature_scalars(arg_count, 4, 0),
+        Function::BinomDistRange => args_signature_scalars(arg_count, 3, 1),
+        Function::BinomInv => args_signature_scalars(arg_count, 3, 0),
+        Function::ChisqDist => args_signature_scalars(arg_count, 4, 0),
+        Function::ChisqDistRT => args_signature_scalars(arg_count, 3, 0),
+        Function::ChisqInv => args_signature_scalars(arg_count, 3, 0),
+        Function::ChisqInvRT => args_signature_scalars(arg_count, 2, 0),
+        Function::ChisqTest => {
+            if arg_count == 2 {
+                vec![Signature::Vector, Signature::Vector]
+            } else {
+                vec![Signature::Error; arg_count]
+            }
+        }
+        Function::ConfidenceNorm => args_signature_scalars(arg_count, 3, 0),
+        Function::ConfidenceT => args_signature_scalars(arg_count, 3, 0),
+        Function::CovarianceP => {
+            if arg_count == 2 {
+                vec![Signature::Vector, Signature::Vector]
+            } else {
+                vec![Signature::Error; arg_count]
+            }
+        }
+        Function::CovarianceS => {
+            if arg_count == 2 {
+                vec![Signature::Vector, Signature::Vector]
+            } else {
+                vec![Signature::Error; arg_count]
+            }
+        }
+        Function::Devsq => vec![Signature::Vector; arg_count],
+        Function::ExponDist => args_signature_scalars(arg_count, 3, 0),
+        Function::FDist => args_signature_scalars(arg_count, 4, 0),
+        Function::FDistRT => args_signature_scalars(arg_count, 3, 0),
+        Function::FInv => args_signature_scalars(arg_count, 3, 0),
+        Function::FInvRT => args_signature_scalars(arg_count, 3, 0),
+        Function::FTest => vec![Signature::Vector; 2],
+        Function::Fisher => args_signature_scalars(arg_count, 1, 0),
+        Function::FisherInv => args_signature_scalars(arg_count, 1, 0),
+        Function::Gamma => args_signature_scalars(arg_count, 1, 0),
+        Function::GammaDist => args_signature_scalars(arg_count, 4, 0),
+        Function::GammaInv => args_signature_scalars(arg_count, 3, 0),
+        Function::GammaLn => args_signature_scalars(arg_count, 1, 0),
+        Function::GammaLnPrecise => args_signature_scalars(arg_count, 1, 0),
+        Function::HypGeomDist => args_signature_scalars(arg_count, 5, 0),
+        Function::LogNormDist => args_signature_scalars(arg_count, 4, 0),
+        Function::LogNormInv => args_signature_scalars(arg_count, 3, 0),
+        Function::NegbinomDist => args_signature_scalars(arg_count, 4, 0),
+        Function::NormDist => args_signature_scalars(arg_count, 4, 0),
+        Function::NormInv => args_signature_scalars(arg_count, 3, 0),
+        Function::NormSdist => args_signature_scalars(arg_count, 2, 0),
+        Function::NormSInv => args_signature_scalars(arg_count, 1, 0),
+        Function::Pearson => {
+            if arg_count == 2 {
+                vec![Signature::Vector, Signature::Vector]
+            } else {
+                vec![Signature::Error; arg_count]
+            }
+        }
+        Function::Phi => args_signature_scalars(arg_count, 1, 0),
+        Function::PoissonDist => args_signature_scalars(arg_count, 3, 0),
+        Function::Standardize => args_signature_scalars(arg_count, 3, 0),
+        Function::StDevP => vec![Signature::Vector; arg_count],
+        Function::StDevS => vec![Signature::Vector; arg_count],
+        Function::Stdeva => vec![Signature::Vector; arg_count],
+        Function::Stdevpa => vec![Signature::Vector; arg_count],
+        Function::TDist => args_signature_scalars(arg_count, 3, 0),
+        Function::TDist2T => args_signature_scalars(arg_count, 2, 0),
+        Function::TDistRT => args_signature_scalars(arg_count, 2, 0),
+        Function::TInv => args_signature_scalars(arg_count, 2, 0),
+        Function::TInv2T => args_signature_scalars(arg_count, 2, 0),
+        Function::TTest => {
+            if arg_count == 4 {
+                vec![
+                    Signature::Vector,
+                    Signature::Vector,
+                    Signature::Scalar,
+                    Signature::Scalar,
+                ]
+            } else {
+                vec![Signature::Error; arg_count]
+            }
+        }
+        Function::VarP => vec![Signature::Vector; arg_count],
+        Function::VarS => vec![Signature::Vector; arg_count],
+        Function::VarpA => vec![Signature::Vector; arg_count],
+        Function::VarA => vec![Signature::Vector; arg_count],
+        Function::WeibullDist => args_signature_scalars(arg_count, 4, 0),
+        Function::ZTest => {
+            if arg_count == 2 {
+                vec![Signature::Vector, Signature::Scalar]
+            } else if arg_count == 3 {
+                vec![Signature::Vector, Signature::Scalar, Signature::Scalar]
+            } else {
+                vec![Signature::Error; arg_count]
+            }
+        }
+        Function::Sumx2my2 => vec![Signature::Vector; 2],
+        Function::Sumx2py2 => vec![Signature::Vector; 2],
+        Function::Sumxmy2 => vec![Signature::Vector; 2],
+        Function::Correl => vec![Signature::Vector; 2],
+        Function::Rsq => vec![Signature::Vector; 2],
+        Function::Intercept => vec![Signature::Vector; 2],
+        Function::Slope => vec![Signature::Vector; 2],
+        Function::Steyx => vec![Signature::Vector; 2],
+        Function::Gauss => args_signature_scalars(arg_count, 1, 0),
+        Function::Harmean => vec![Signature::Vector; arg_count],
+        Function::Kurt => vec![Signature::Vector; arg_count],
+        Function::Large => vec![Signature::Vector, Signature::Scalar],
+        Function::MaxA => vec![Signature::Vector; arg_count],
+        Function::Median => vec![Signature::Vector; arg_count],
+        Function::MinA => vec![Signature::Vector; arg_count],
+        Function::RankAvg => vec![Signature::Scalar, Signature::Vector, Signature::Scalar],
+        Function::RankEq => vec![Signature::Scalar, Signature::Vector, Signature::Scalar],
+        Function::Skew => vec![Signature::Vector; arg_count],
+        Function::SkewP => vec![Signature::Vector; arg_count],
+        Function::Small => vec![Signature::Vector, Signature::Scalar],
     }
 }
 
@@ -810,7 +1032,7 @@ fn static_analysis_on_function(kind: &Function, args: &[Node]) -> StaticResult {
         Function::Atan => scalar_arguments(args),
         Function::Atan2 => scalar_arguments(args),
         Function::Atanh => scalar_arguments(args),
-        Function::Choose => scalar_arguments(args), // static_analysis_choose(args, cell),
+        Function::Choose => scalar_arguments(args),
         Function::Column => not_implemented(args),
         Function::Columns => not_implemented(args),
         Function::Cos => scalar_arguments(args),
@@ -857,7 +1079,6 @@ fn static_analysis_on_function(kind: &Function, args: &[Node]) -> StaticResult {
         Function::Lookup => not_implemented(args),
         Function::Match => not_implemented(args),
         Function::Offset => static_analysis_offset(args),
-        // FIXME: Row could return an array
         Function::Row => StaticResult::Scalar,
         Function::Rows => not_implemented(args),
         Function::Vlookup => not_implemented(args),
@@ -886,6 +1107,7 @@ fn static_analysis_on_function(kind: &Function, args: &[Node]) -> StaticResult {
         Function::Valuetotext => not_implemented(args),
         Function::Average => not_implemented(args),
         Function::Averagea => not_implemented(args),
+        Function::Avedev => not_implemented(args),
         Function::Averageif => not_implemented(args),
         Function::Averageifs => not_implemented(args),
         Function::Count => not_implemented(args),
@@ -896,12 +1118,27 @@ fn static_analysis_on_function(kind: &Function, args: &[Node]) -> StaticResult {
         Function::Maxifs => not_implemented(args),
         Function::Minifs => not_implemented(args),
         Function::Date => not_implemented(args),
+        Function::Datedif => not_implemented(args),
+        Function::Datevalue => not_implemented(args),
         Function::Day => not_implemented(args),
         Function::Edate => not_implemented(args),
         Function::Month => not_implemented(args),
+        Function::Time => not_implemented(args),
+        Function::Timevalue => not_implemented(args),
+        Function::Hour => not_implemented(args),
+        Function::Minute => not_implemented(args),
+        Function::Second => not_implemented(args),
         Function::Now => not_implemented(args),
         Function::Today => not_implemented(args),
         Function::Year => not_implemented(args),
+        Function::Days => not_implemented(args),
+        Function::Days360 => not_implemented(args),
+        Function::Weekday => not_implemented(args),
+        Function::Weeknum => not_implemented(args),
+        Function::Workday => not_implemented(args),
+        Function::WorkdayIntl => not_implemented(args),
+        Function::Yearfrac => not_implemented(args),
+        Function::Isoweeknum => not_implemented(args),
         Function::Cumipmt => not_implemented(args),
         Function::Cumprinc => not_implemented(args),
         Function::Db => not_implemented(args),
@@ -990,5 +1227,136 @@ fn static_analysis_on_function(kind: &Function, args: &[Node]) -> StaticResult {
         Function::Eomonth => scalar_arguments(args),
         Function::Formulatext => not_implemented(args),
         Function::Geomean => not_implemented(args),
+        Function::Networkdays => not_implemented(args),
+        Function::NetworkdaysIntl => not_implemented(args),
+        Function::Acot => scalar_arguments(args),
+        Function::Acoth => scalar_arguments(args),
+        Function::Cot => scalar_arguments(args),
+        Function::Coth => scalar_arguments(args),
+        Function::Csc => scalar_arguments(args),
+        Function::Csch => scalar_arguments(args),
+        Function::Sec => scalar_arguments(args),
+        Function::Sech => scalar_arguments(args),
+        Function::Exp => scalar_arguments(args),
+        Function::Fact => scalar_arguments(args),
+        Function::Factdouble => scalar_arguments(args),
+        Function::Sign => scalar_arguments(args),
+        Function::Radians => scalar_arguments(args),
+        Function::Degrees => scalar_arguments(args),
+        Function::Int => scalar_arguments(args),
+        Function::Even => scalar_arguments(args),
+        Function::Odd => scalar_arguments(args),
+        Function::Ceiling => scalar_arguments(args),
+        Function::CeilingMath => scalar_arguments(args),
+        Function::CeilingPrecise => scalar_arguments(args),
+        Function::Floor => scalar_arguments(args),
+        Function::FloorMath => scalar_arguments(args),
+        Function::FloorPrecise => scalar_arguments(args),
+        Function::IsoCeiling => scalar_arguments(args),
+        Function::Mod => scalar_arguments(args),
+        Function::Quotient => scalar_arguments(args),
+        Function::Mround => scalar_arguments(args),
+        Function::Trunc => scalar_arguments(args),
+        Function::Gcd => not_implemented(args),
+        Function::Lcm => not_implemented(args),
+        Function::Base => scalar_arguments(args),
+        Function::Decimal => scalar_arguments(args),
+        Function::Roman => scalar_arguments(args),
+        Function::Arabic => scalar_arguments(args),
+        Function::Combin => scalar_arguments(args),
+        Function::Combina => scalar_arguments(args),
+        Function::Sumsq => StaticResult::Scalar,
+        Function::N => scalar_arguments(args),
+        Function::Sheets => scalar_arguments(args),
+        Function::Cell => scalar_arguments(args),
+        Function::Info => scalar_arguments(args),
+        Function::Dget => not_implemented(args),
+        Function::Dmax => not_implemented(args),
+        Function::Dmin => not_implemented(args),
+        Function::Dcount => not_implemented(args),
+        Function::Daverage => not_implemented(args),
+        Function::Dsum => not_implemented(args),
+        Function::Dcounta => not_implemented(args),
+        Function::Dproduct => not_implemented(args),
+        Function::Dstdev => not_implemented(args),
+        Function::Dvar => not_implemented(args),
+        Function::Dvarp => not_implemented(args),
+        Function::Dstdevp => not_implemented(args),
+        Function::BetaDist => StaticResult::Scalar,
+        Function::BetaInv => StaticResult::Scalar,
+        Function::BinomDist => StaticResult::Scalar,
+        Function::BinomDistRange => StaticResult::Scalar,
+        Function::BinomInv => StaticResult::Scalar,
+        Function::ChisqDist => StaticResult::Scalar,
+        Function::ChisqDistRT => StaticResult::Scalar,
+        Function::ChisqInv => StaticResult::Scalar,
+        Function::ChisqInvRT => StaticResult::Scalar,
+        Function::ChisqTest => StaticResult::Scalar,
+        Function::ConfidenceNorm => StaticResult::Scalar,
+        Function::ConfidenceT => StaticResult::Scalar,
+        Function::CovarianceP => StaticResult::Scalar,
+        Function::CovarianceS => StaticResult::Scalar,
+        Function::Devsq => StaticResult::Scalar,
+        Function::ExponDist => StaticResult::Scalar,
+        Function::FDist => StaticResult::Scalar,
+        Function::FDistRT => StaticResult::Scalar,
+        Function::FInv => StaticResult::Scalar,
+        Function::FInvRT => StaticResult::Scalar,
+        Function::FTest => StaticResult::Scalar,
+        Function::Fisher => StaticResult::Scalar,
+        Function::FisherInv => StaticResult::Scalar,
+        Function::Gamma => StaticResult::Scalar,
+        Function::GammaDist => StaticResult::Scalar,
+        Function::GammaInv => StaticResult::Scalar,
+        Function::GammaLn => StaticResult::Scalar,
+        Function::GammaLnPrecise => StaticResult::Scalar,
+        Function::HypGeomDist => StaticResult::Scalar,
+        Function::LogNormDist => StaticResult::Scalar,
+        Function::LogNormInv => StaticResult::Scalar,
+        Function::NegbinomDist => StaticResult::Scalar,
+        Function::NormDist => StaticResult::Scalar,
+        Function::NormInv => StaticResult::Scalar,
+        Function::NormSdist => StaticResult::Scalar,
+        Function::NormSInv => StaticResult::Scalar,
+        Function::Pearson => StaticResult::Scalar,
+        Function::Phi => StaticResult::Scalar,
+        Function::PoissonDist => StaticResult::Scalar,
+        Function::Standardize => StaticResult::Scalar,
+        Function::StDevP => StaticResult::Scalar,
+        Function::StDevS => StaticResult::Scalar,
+        Function::Stdeva => StaticResult::Scalar,
+        Function::Stdevpa => StaticResult::Scalar,
+        Function::TDist => StaticResult::Scalar,
+        Function::TDist2T => StaticResult::Scalar,
+        Function::TDistRT => StaticResult::Scalar,
+        Function::TInv => StaticResult::Scalar,
+        Function::TInv2T => StaticResult::Scalar,
+        Function::TTest => StaticResult::Scalar,
+        Function::VarP => StaticResult::Scalar,
+        Function::VarS => StaticResult::Scalar,
+        Function::VarpA => StaticResult::Scalar,
+        Function::VarA => StaticResult::Scalar,
+        Function::WeibullDist => StaticResult::Scalar,
+        Function::ZTest => StaticResult::Scalar,
+        Function::Sumx2my2 => StaticResult::Scalar,
+        Function::Sumx2py2 => StaticResult::Scalar,
+        Function::Sumxmy2 => StaticResult::Scalar,
+        Function::Correl => StaticResult::Scalar,
+        Function::Rsq => StaticResult::Scalar,
+        Function::Intercept => StaticResult::Scalar,
+        Function::Slope => StaticResult::Scalar,
+        Function::Steyx => StaticResult::Scalar,
+        Function::Gauss => StaticResult::Scalar,
+        Function::Harmean => StaticResult::Scalar,
+        Function::Kurt => StaticResult::Scalar,
+        Function::Large => StaticResult::Scalar,
+        Function::MaxA => StaticResult::Scalar,
+        Function::Median => StaticResult::Scalar,
+        Function::MinA => StaticResult::Scalar,
+        Function::RankAvg => StaticResult::Scalar,
+        Function::RankEq => StaticResult::Scalar,
+        Function::Skew => StaticResult::Scalar,
+        Function::SkewP => StaticResult::Scalar,
+        Function::Small => StaticResult::Scalar,
     }
 }

base/src/expressions/parser/stringify.rs

@@ -520,6 +520,7 @@ fn stringify(
             let x = match **left {
                 BooleanKind(_)
                 | NumberKind(_)
+                | UnaryKind { .. }
                 | StringKind(_)
                 | ReferenceKind { .. }
                 | RangeKind { .. }
@@ -535,7 +536,6 @@ fn stringify(
                 | FunctionKind { .. }
                 | InvalidFunctionKind { .. }
                 | ArrayKind(_)
-                | UnaryKind { .. }
                 | ErrorKind(_)
                 | ParseErrorKind { .. }
                 | OpSumKind { .. }
@@ -630,7 +630,6 @@ fn stringify(
                     | OpRangeKind { .. }
                     | OpConcatenateKind { .. }
                     | OpProductKind { .. }
-                    | OpPowerKind { .. }
                     | FunctionKind { .. }
                     | InvalidFunctionKind { .. }
                     | ArrayKind(_)
@@ -643,7 +642,7 @@ fn stringify(
                     | ParseErrorKind { .. }
                     | EmptyArgKind => false,
 
-                    OpSumKind { .. } | UnaryKind { .. } => true,
+                    OpPowerKind { .. } | OpSumKind { .. } | UnaryKind { .. } => true,
                 };
                 if needs_parentheses {
                     format!(

base/src/expressions/parser/tests/mod.rs

@@ -3,6 +3,7 @@ mod test_arrays;
 mod test_general;
 mod test_implicit_intersection;
 mod test_issue_155;
+mod test_issue_483;
 mod test_move_formula;
 mod test_ranges;
 mod test_stringify;

base/src/expressions/parser/tests/test_issue_483.rs

@@ -0,0 +1,27 @@
+#![allow(clippy::panic)]
+
+use std::collections::HashMap;
+
+use crate::expressions::parser::stringify::to_string;
+use crate::expressions::parser::{Node, Parser};
+use crate::expressions::types::CellReferenceRC;
+
+#[test]
+fn issue_483_parser() {
+    let worksheets = vec!["Sheet1".to_string()];
+    let mut parser = Parser::new(worksheets, vec![], HashMap::new());
+
+    // Reference cell is Sheet1!A1
+    let cell_reference = CellReferenceRC {
+        sheet: "Sheet1".to_string(),
+        row: 2,
+        column: 2,
+    };
+    let t = parser.parse("-(A1^1.22)", &cell_reference);
+    assert!(matches!(t, Node::UnaryKind { .. }));
+    assert_eq!(to_string(&t, &cell_reference), "-(A1^1.22)");
+
+    let t = parser.parse("-A1^1.22", &cell_reference);
+    assert!(matches!(t, Node::OpPowerKind { .. }));
+    assert_eq!(to_string(&t, &cell_reference), "-A1^1.22");
+}

base/src/expressions/utils/mod.rs

@@ -211,15 +211,19 @@ pub fn parse_reference_a1(r: &str) -> Option<ParsedReference> {
 pub fn is_valid_identifier(name: &str) -> bool {
     // https://support.microsoft.com/en-us/office/names-in-formulas-fc2935f9-115d-4bef-a370-3aa8bb4c91f1
     // https://github.com/MartinTrummer/excel-names/
-    // NOTE: We are being much more restrictive than Excel.
-    // In particular we do not support non ascii characters.
     let upper = name.to_ascii_uppercase();
-    let bytes = upper.as_bytes();
-    let len = bytes.len();
+    // length of chars
+    let len = upper.chars().count();
+
+    let mut chars = upper.chars();
+
     if len > 255 || len == 0 {
         return false;
     }
-    let first = bytes[0] as char;
+    let first = match chars.next() {
+        Some(ch) => ch,
+        None => return false,
+    };
     // The first character of a name must be a letter, an underscore character (_), or a backslash (\).
     if !(first.is_ascii_alphabetic() || first == '_' || first == '\\') {
         return false;
@@ -237,21 +241,11 @@ pub fn is_valid_identifier(name: &str) -> bool {
     if parse_reference_r1c1(name).is_some() {
         return false;
     }
-    let mut i = 1;
-    while i < len {
-        let ch = bytes[i] as char;
-        match ch {
-            'a'..='z' => {}
-            'A'..='Z' => {}
-            '0'..='9' => {}
-            '_' => {}
-            '.' => {}
-            _ => {
+    for ch in chars {
+        if !(ch.is_alphanumeric() || ch == '_' || ch == '.') {
             return false;
         }
     }
-        i += 1;
-    }
 
     true
 }
@@ -259,15 +253,23 @@ pub fn is_valid_identifier(name: &str) -> bool {
 fn name_needs_quoting(name: &str) -> bool {
     let chars = name.chars();
     // it contains any of these characters: ()'$,;-+{} or space
-    for char in chars {
+    for (i, char) in chars.enumerate() {
         if [' ', '(', ')', '\'', '$', ',', ';', '-', '+', '{', '}'].contains(&char) {
             return true;
         }
+        // if it starts with a number
+        if i == 0 && char.is_ascii_digit() {
+            return true;
         }
-    // TODO:
+    }
+    if parse_reference_a1(name).is_some() {
         // cell reference in A1 notation, e.g. B1048576 is quoted, B1048577 is not
+        return true;
+    }
+    if parse_reference_r1c1(name).is_some() {
         // cell reference in R1C1 notation, e.g. RC, RC2, R5C, R-4C, RC-8, R, C
-    // integers
+        return true;
+    }
     false
 }
 
@@ -279,3 +281,32 @@ pub fn quote_name(name: &str) -> String {
     };
     name.to_string()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_quote_name() {
+        assert_eq!(quote_name("Sheet1"), "Sheet1");
+        assert_eq!(quote_name("Sheet 1"), "'Sheet 1'");
+        // escape and quote
+        assert_eq!(quote_name("Sheet1'"), "'Sheet1'''");
+        assert_eq!(quote_name("Data(2024)"), "'Data(2024)'");
+        assert_eq!(quote_name("Data$2024"), "'Data$2024'");
+        assert_eq!(quote_name("Data-2024"), "'Data-2024'");
+        assert_eq!(quote_name("Data+2024"), "'Data+2024'");
+        assert_eq!(quote_name("Data,2024"), "'Data,2024'");
+        assert_eq!(quote_name("Data;2024"), "'Data;2024'");
+        assert_eq!(quote_name("Data{2024}"), "'Data{2024}'");
+
+        assert_eq!(quote_name("2024"), "'2024'");
+        assert_eq!(quote_name("1Data"), "'1Data'");
+        assert_eq!(quote_name("A1"), "'A1'");
+        assert_eq!(quote_name("R1C1"), "'R1C1'");
+        assert_eq!(quote_name("MySheet"), "MySheet");
+
+        assert_eq!(quote_name("B1048576"), "'B1048576'");
+        assert_eq!(quote_name("B1048577"), "B1048577");
+    }
+}

base/src/expressions/utils/test.rs

@@ -196,6 +196,7 @@ fn test_names() {
     assert!(is_valid_identifier("_."));
     assert!(is_valid_identifier("_1"));
     assert!(is_valid_identifier("\\."));
+    assert!(is_valid_identifier("truñe"));
 
     // invalid
     assert!(!is_valid_identifier("true"));
@@ -209,7 +210,6 @@ fn test_names() {
     assert!(!is_valid_identifier("1true"));
 
     assert!(!is_valid_identifier("test€"));
-    assert!(!is_valid_identifier("truñe"));
     assert!(!is_valid_identifier("tr&ue"));
 
     assert!(!is_valid_identifier("LOG10"));

base/src/formatter/dates.rs

@@ -8,6 +8,8 @@ use crate::constants::EXCEL_DATE_BASE;
 use crate::constants::MAXIMUM_DATE_SERIAL_NUMBER;
 use crate::constants::MINIMUM_DATE_SERIAL_NUMBER;
 
+pub const DATE_OUT_OF_RANGE_MESSAGE: &str = "Out of range parameters for date";
+
 #[inline]
 fn convert_to_serial_number(date: NaiveDate) -> i32 {
     date.num_days_from_ce() - EXCEL_DATE_BASE
@@ -37,7 +39,7 @@ pub fn from_excel_date(days: i64) -> Result<NaiveDate, String> {
 pub fn date_to_serial_number(day: u32, month: u32, year: i32) -> Result<i32, String> {
     match NaiveDate::from_ymd_opt(year, month, day) {
         Some(native_date) => Ok(convert_to_serial_number(native_date)),
-        None => Err("Out of range parameters for date".to_string()),
+        None => Err(DATE_OUT_OF_RANGE_MESSAGE.to_string()),
     }
 }
 
@@ -55,7 +57,7 @@ pub fn permissive_date_to_serial_number(day: i32, month: i32, year: i32) -> Resu
         return Ok(MINIMUM_DATE_SERIAL_NUMBER);
     }
     let Some(mut date) = NaiveDate::from_ymd_opt(year, 1, 1) else {
-        return Err("Out of range parameters for date".to_string());
+        return Err(DATE_OUT_OF_RANGE_MESSAGE.to_string());
     };
 
     // One thing to note for example is that even if you started with a year out of range
@@ -68,7 +70,7 @@ pub fn permissive_date_to_serial_number(day: i32, month: i32, year: i32) -> Resu
     // As a result, we have to run range checks as we parse the date from the biggest unit to the
     // smallest unit.
     if !is_date_within_range(date) {
-        return Err("Out of range parameters for date".to_string());
+        return Err(DATE_OUT_OF_RANGE_MESSAGE.to_string());
     }
 
     date = {
@@ -80,7 +82,7 @@ pub fn permissive_date_to_serial_number(day: i32, month: i32, year: i32) -> Resu
             date = date + Months::new(abs_month);
         }
         if !is_date_within_range(date) {
-            return Err("Out of range parameters for date".to_string());
+            return Err(DATE_OUT_OF_RANGE_MESSAGE.to_string());
         }
         date
     };
@@ -94,7 +96,7 @@ pub fn permissive_date_to_serial_number(day: i32, month: i32, year: i32) -> Resu
             date = date + Days::new(abs_day);
         }
         if !is_date_within_range(date) {
-            return Err("Out of range parameters for date".to_string());
+            return Err(DATE_OUT_OF_RANGE_MESSAGE.to_string());
         }
         date
     };

base/src/formatter/format.rs

@@ -15,7 +15,7 @@ pub struct Formatted {
 
 /// Returns the vector of chars of the fractional part of a *positive* number:
 /// 3.1415926 ==> ['1', '4', '1', '5', '9', '2', '6']
-fn get_fract_part(value: f64, precision: i32) -> Vec<char> {
+fn get_fract_part(value: f64, precision: i32, int_len: usize) -> Vec<char> {
     let b = format!("{:.1$}", value.fract(), precision as usize)
         .chars()
         .collect::<Vec<char>>();
@@ -30,6 +30,12 @@ fn get_fract_part(value: f64, precision: i32) -> Vec<char> {
     if last_non_zero < 2 {
         return vec![];
     }
+    let max_len = if int_len > 15 {
+        2_usize
+    } else {
+        15_usize - int_len + 1
+    };
+    let last_non_zero = usize::min(last_non_zero, max_len + 1);
     b[2..last_non_zero].to_vec()
 }
 
@@ -154,16 +160,11 @@ pub fn format_number(value_original: f64, format: &str, locale: &Locale) -> Form
         ParsePart::Date(p) => {
             let tokens = &p.tokens;
             let mut text = "".to_string();
-            let date = match from_excel_date(value as i64) {
-                Ok(d) => d,
-                Err(e) => {
-                    return Formatted {
-                        text: "#VALUE!".to_owned(),
-                        color: None,
-                        error: Some(e),
-                    }
-                }
-            };
+            let time_fract = value.fract();
+            let hours = (time_fract * 24.0).floor();
+            let minutes = ((time_fract * 24.0 - hours) * 60.0).floor();
+            let seconds = ((((time_fract * 24.0 - hours) * 60.0) - minutes) * 60.0).round();
+            let date = from_excel_date(value as i64).ok();
             for token in tokens {
                 match token {
                     TextToken::Literal(c) => {
@@ -187,15 +188,44 @@ pub fn format_number(value_original: f64, format: &str, locale: &Locale) -> Form
                     }
                     TextToken::Digit(_) => {}
                     TextToken::Period => {}
-                    TextToken::Day => {
+                    TextToken::Day => match date {
+                        Some(date) => {
                             let day = date.day() as usize;
                             text = format!("{text}{day}");
                         }
+                        None => {
+                            return Formatted {
+                                text: "#VALUE!".to_owned(),
+                                color: None,
+                                error: Some(format!("Invalid date value: '{value}'")),
+                            }
+                        }
+                    },
                     TextToken::DayPadded => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let day = date.day() as usize;
                         text = format!("{text}{day:02}");
                     }
                     TextToken::DayNameShort => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let mut day = date.weekday().number_from_monday() as usize;
                         if day == 7 {
                             day = 0;
@@ -203,6 +233,16 @@ pub fn format_number(value_original: f64, format: &str, locale: &Locale) -> Form
                         text = format!("{}{}", text, &locale.dates.day_names_short[day]);
                     }
                     TextToken::DayName => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let mut day = date.weekday().number_from_monday() as usize;
                         if day == 7 {
                             day = 0;
@@ -210,32 +250,144 @@ pub fn format_number(value_original: f64, format: &str, locale: &Locale) -> Form
                         text = format!("{}{}", text, &locale.dates.day_names[day]);
                     }
                     TextToken::Month => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let month = date.month() as usize;
                         text = format!("{text}{month}");
                     }
                     TextToken::MonthPadded => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let month = date.month() as usize;
                         text = format!("{text}{month:02}");
                     }
                     TextToken::MonthNameShort => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let month = date.month() as usize;
                         text = format!("{}{}", text, &locale.dates.months_short[month - 1]);
                     }
                     TextToken::MonthName => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let month = date.month() as usize;
                         text = format!("{}{}", text, &locale.dates.months[month - 1]);
                     }
                     TextToken::MonthLetter => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         let month = date.month() as usize;
                         let months_letter = &locale.dates.months_letter[month - 1];
                         text = format!("{text}{months_letter}");
                     }
                     TextToken::YearShort => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         text = format!("{}{}", text, date.format("%y"));
                     }
                     TextToken::Year => {
+                        let date = match date {
+                            Some(d) => d,
+                            None => {
+                                return Formatted {
+                                    text: "#VALUE!".to_owned(),
+                                    color: None,
+                                    error: Some(format!("Invalid date value: '{value}'")),
+                                }
+                            }
+                        };
                         text = format!("{}{}", text, date.year());
                     }
+                    TextToken::Hour => {
+                        let mut hour = hours as i32;
+                        if p.use_ampm {
+                            if hour == 0 {
+                                hour = 12;
+                            } else if hour > 12 {
+                                hour -= 12;
+                            }
+                        }
+                        text = format!("{text}{hour}");
+                    }
+                    TextToken::HourPadded => {
+                        let mut hour = hours as i32;
+                        if p.use_ampm {
+                            if hour == 0 {
+                                hour = 12;
+                            } else if hour > 12 {
+                                hour -= 12;
+                            }
+                        }
+                        text = format!("{text}{hour:02}");
+                    }
+                    TextToken::Second => {
+                        let second = seconds as i32;
+                        text = format!("{text}{second}");
+                    }
+                    TextToken::SecondPadded => {
+                        let second = seconds as i32;
+                        text = format!("{text}{second:02}");
+                    }
+                    TextToken::AMPM => {
+                        let ampm = if hours < 12.0 { "AM" } else { "PM" };
+                        text = format!("{text}{ampm}");
+                    }
+                    TextToken::Minute => {
+                        let minute = minutes as i32;
+                        text = format!("{text}{minute}");
+                    }
+                    TextToken::MinutePadded => {
+                        let minute = minutes as i32;
+                        text = format!("{text}{minute:02}");
+                    }
                 }
             }
             Formatted {
@@ -277,7 +429,7 @@ pub fn format_number(value_original: f64, format: &str, locale: &Locale) -> Form
             if value_abs as i64 == 0 {
                 int_part = vec![];
             }
-            let fract_part = get_fract_part(value_abs, p.precision);
+            let fract_part = get_fract_part(value_abs, p.precision, int_part.len());
             // ln is the number of digits of the integer part of the value
             let ln = int_part.len() as i32;
             // digit count is the number of digit tokens ('0', '?' and '#') to the left of the decimal point
@@ -422,6 +574,13 @@ pub fn format_number(value_original: f64, format: &str, locale: &Locale) -> Form
                     TextToken::MonthLetter => {}
                     TextToken::YearShort => {}
                     TextToken::Year => {}
+                    TextToken::Hour => {}
+                    TextToken::HourPadded => {}
+                    TextToken::Minute => {}
+                    TextToken::MinutePadded => {}
+                    TextToken::Second => {}
+                    TextToken::SecondPadded => {}
+                    TextToken::AMPM => {}
                 }
             }
             Formatted {
@@ -591,10 +750,10 @@ fn parse_date(value: &str) -> Result<(i32, String), String> {
 /// "30.34%" => (0.3034, "0.00%")
 /// 100€ => (100, "100€")
 pub(crate) fn parse_formatted_number(
-    value: &str,
+    original: &str,
     currencies: &[&str],
 ) -> Result<(f64, Option<String>), String> {
-    let value = value.trim();
+    let value = original.trim();
     let scientific_format = "0.00E+00";
 
     // Check if it is a percentage
@@ -646,7 +805,8 @@ pub(crate) fn parse_formatted_number(
         }
     }
 
-    if let Ok((serial_number, format)) = parse_date(value) {
+    // check if it is a date. NOTE: we don't trim the original here
+    if let Ok((serial_number, format)) = parse_date(original) {
         return Ok((serial_number as f64, Some(format)));
     }
 

base/src/formatter/lexer.rs

@@ -26,19 +26,23 @@ pub enum Token {
     Scientific,    // E+
     ScientificMinus, // E-
     General,       // General
-    // Dates
+    // Dates and time
     Day,            // d
     DayPadded,      // dd
     DayNameShort,   // ddd
     DayName,        // dddd+
-    Month,          // m
-    MonthPadded,    // mm
+    Month,          // m (or minute)
+    MonthPadded,    // mm (or minute padded)
     MonthNameShort, // mmm
     MonthName,      // mmmm or mmmmmm+
     MonthLetter,    // mmmmm
     YearShort,      // y or yy
     Year,           // yyy+
-    // TODO: Hours Minutes and Seconds
+    Hour,           // h
+    HourPadded,     // hh
+    Second,         // s
+    SecondPadded,   // ss
+    AMPM,           // AM/PM (or A/P)
     ILLEGAL,
     EOF,
 }
@@ -361,8 +365,8 @@ impl Lexer {
                         self.read_next_char();
                     }
                     match m {
-                        1 => Token::Month,
-                        2 => Token::MonthPadded,
+                        1 => Token::Month,       // (or minute)
+                        2 => Token::MonthPadded, // (or minute padded)
                         3 => Token::MonthNameShort,
                         4 => Token::MonthName,
                         5 => Token::MonthLetter,
@@ -381,6 +385,63 @@ impl Lexer {
                         Token::Year
                     }
                 }
+                'h' => {
+                    let mut h = 1;
+                    while let Some('h') = self.peek_char() {
+                        h += 1;
+                        self.read_next_char();
+                    }
+                    if h == 1 {
+                        Token::Hour
+                    } else if h == 2 {
+                        Token::HourPadded
+                    } else {
+                        self.set_error("Unexpected character after 'h'");
+                        Token::ILLEGAL
+                    }
+                }
+                's' => {
+                    let mut s = 1;
+                    while let Some('s') = self.peek_char() {
+                        s += 1;
+                        self.read_next_char();
+                    }
+                    if s == 1 {
+                        Token::Second
+                    } else if s == 2 {
+                        Token::SecondPadded
+                    } else {
+                        self.set_error("Unexpected character after 's'");
+                        Token::ILLEGAL
+                    }
+                }
+                'A' | 'a' => {
+                    if let Some('M') | Some('m') = self.peek_char() {
+                        self.read_next_char();
+                    } else {
+                        self.set_error("Unexpected character after 'A'");
+                        return Token::ILLEGAL;
+                    }
+                    if let Some('/') = self.peek_char() {
+                        self.read_next_char();
+                    } else {
+                        self.set_error("Unexpected character after 'AM'");
+                        return Token::ILLEGAL;
+                    }
+                    if let Some('P') | Some('p') = self.peek_char() {
+                        self.read_next_char();
+                    } else {
+                        self.set_error("Unexpected character after 'AM'");
+                        return Token::ILLEGAL;
+                    }
+                    if let Some('M') | Some('m') = self.peek_char() {
+                        self.read_next_char();
+                    } else {
+                        self.set_error("Unexpected character after 'AMP'");
+                        return Token::ILLEGAL;
+                    }
+                    Token::AMPM
+                }
                 'g' | 'G' => {
                     for c in "eneral".chars() {
                         let cc = self.read_next_char();

base/src/formatter/parser.rs

@@ -27,6 +27,13 @@ pub enum TextToken {
     MonthLetter,
     YearShort,
     Year,
+    Hour,
+    HourPadded,
+    Minute,
+    MinutePadded,
+    Second,
+    SecondPadded,
+    AMPM,
 }
 pub struct NumberPart {
     pub color: Option<i32>,
@@ -45,6 +52,7 @@ pub struct NumberPart {
 
 pub struct DatePart {
     pub color: Option<i32>,
+    pub use_ampm: bool,
     pub tokens: Vec<TextToken>,
 }
 
@@ -101,6 +109,7 @@ impl Parser {
         let mut digit_count = 0;
         let mut precision = 0;
         let mut is_date = false;
+        let mut use_ampm = false;
         let mut is_number = false;
         let mut found_decimal_dot = false;
         let mut use_thousands = false;
@@ -116,6 +125,7 @@ impl Parser {
         let mut number = 'i';
         let mut index = 0;
         let mut currency = None;
+        let mut is_time = false;
 
         while token != Token::EOF && token != Token::Separator {
             let next_token = self.lexer.next_token();
@@ -200,6 +210,9 @@ impl Parser {
                     index += 1;
                 }
                 Token::Literal(value) => {
+                    if value == ':' {
+                        is_time = true;
+                    }
                     tokens.push(TextToken::Literal(value));
                 }
                 Token::Text(value) => {
@@ -236,13 +249,23 @@ impl Parser {
                     tokens.push(TextToken::MonthName);
                 }
                 Token::Month => {
+                    if is_time {
+                        // minute
+                        tokens.push(TextToken::Minute);
+                    } else {
                         is_date = true;
                         tokens.push(TextToken::Month);
                     }
+                }
                 Token::MonthPadded => {
+                    if is_time {
+                        // minute padded
+                        tokens.push(TextToken::MinutePadded);
+                    } else {
                         is_date = true;
                         tokens.push(TextToken::MonthPadded);
                     }
+                }
                 Token::MonthLetter => {
                     is_date = true;
                     tokens.push(TextToken::MonthLetter);
@@ -255,6 +278,32 @@ impl Parser {
                     is_date = true;
                     tokens.push(TextToken::Year);
                 }
+                Token::Hour => {
+                    is_date = true;
+                    is_time = true;
+                    tokens.push(TextToken::Hour);
+                }
+                Token::HourPadded => {
+                    is_date = true;
+                    is_time = true;
+                    tokens.push(TextToken::HourPadded);
+                }
+                Token::Second => {
+                    is_date = true;
+                    is_time = true;
+                    tokens.push(TextToken::Second);
+                }
+                Token::SecondPadded => {
+                    is_date = true;
+                    is_time = true;
+                    tokens.push(TextToken::SecondPadded);
+                }
+
+                Token::AMPM => {
+                    is_date = true;
+                    use_ampm = true;
+                    tokens.push(TextToken::AMPM);
+                }
                 Token::Scientific => {
                     if !is_scientific {
                         index = 0;
@@ -282,7 +331,11 @@ impl Parser {
             if is_number {
                 return ParsePart::Error(ErrorPart {});
             }
-            ParsePart::Date(DatePart { color, tokens })
+            ParsePart::Date(DatePart {
+                color,
+                use_ampm,
+                tokens,
+            })
         } else {
             ParsePart::Number(NumberPart {
                 color,

base/src/formatter/test/mod.rs

@@ -1,2 +1,3 @@
 mod test_general;
 mod test_parse_formatted_number;
+mod test_time;

base/src/formatter/test/test_time.rs

@@ -0,0 +1,32 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::{
+    formatter::format::format_number,
+    locale::{get_locale, Locale},
+};
+
+fn get_default_locale() -> &'static Locale {
+    get_locale("en").unwrap()
+}
+
+#[test]
+fn simple_test() {
+    let locale = get_default_locale();
+    let format = "h:mm AM/PM";
+    let value = 16.001_423_611_111_11; // =1/86400 => 12:02 AM
+    let formatted = format_number(value, format, locale);
+    assert_eq!(formatted.text, "12:02 AM");
+}
+
+#[test]
+fn padded_vs_unpadded() {
+    let locale = get_default_locale();
+    let padded_format = "hh:mm:ss AM/PM";
+    let unpadded_format = "h:m:s AM/PM";
+    let value = 0.25351851851851853; // => 6:05:04 AM (21904/(24*60*60)) where 21904 = 6 * 3600 + 5*60 + 4
+    let formatted = format_number(value, padded_format, locale);
+    assert_eq!(formatted.text, "06:05:04 AM");
+
+    let formatted = format_number(value, unpadded_format, locale);
+    assert_eq!(formatted.text, "6:5:4 AM");
+}

base/src/functions/database.rs

@@ -0,0 +1,946 @@
+use chrono::Datelike;
+
+use crate::{
+    calc_result::CalcResult,
+    expressions::{parser::Node, token::Error, types::CellReferenceIndex},
+    formatter::dates::date_to_serial_number,
+    Model,
+};
+
+use super::util::{compare_values, from_wildcard_to_regex, result_matches_regex};
+
+impl Model {
+    // =DAVERAGE(database, field, criteria)
+    pub(crate) fn fn_daverage(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        let field_col = match self.resolve_db_field_column(db_left, db_right, &args[1], cell) {
+            Ok(c) => c,
+            Err(e) => return e,
+        };
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            };
+        }
+
+        let mut sum = 0.0f64;
+        let mut count = 0usize;
+
+        let mut row = db_left.row + 1; // skip header
+        while row <= db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                let v = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                });
+                if let CalcResult::Number(n) = v {
+                    if n.is_finite() {
+                        sum += n;
+                        count += 1;
+                    }
+                }
+            }
+            row += 1;
+        }
+
+        if count == 0 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "No numeric values matched criteria".to_string(),
+            };
+        }
+
+        CalcResult::Number(sum / count as f64)
+    }
+
+    // =DCOUNT(database, field, criteria)
+    // Counts numeric entries in the field for rows that match criteria
+    pub(crate) fn fn_dcount(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        let field_col = match self.resolve_db_field_column(db_left, db_right, &args[1], cell) {
+            Ok(c) => c,
+            Err(e) => return e,
+        };
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            };
+        }
+
+        let mut count = 0usize;
+        let mut row = db_left.row + 1; // skip header
+        while row <= db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                let v = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                });
+                if matches!(v, CalcResult::Number(_)) {
+                    count += 1;
+                }
+            }
+            row += 1;
+        }
+
+        CalcResult::Number(count as f64)
+    }
+
+    // =DGET(database, field, criteria)
+    // Returns the (single) field value for the unique matching row
+    pub(crate) fn fn_dget(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        let field_col = match self.resolve_db_field_column(db_left, db_right, &args[1], cell) {
+            Ok(c) => c,
+            Err(e) => return e,
+        };
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            };
+        }
+
+        let mut result: Option<CalcResult> = None;
+        let mut matches = 0usize;
+
+        let mut row = db_left.row + 1;
+        while row <= db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                matches += 1;
+                if matches > 1 {
+                    return CalcResult::Error {
+                        error: Error::NUM,
+                        origin: cell,
+                        message: "More than one matching record".to_string(),
+                    };
+                }
+                result = Some(self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                }));
+            }
+            row += 1;
+        }
+
+        match (matches, result) {
+            (0, _) | (_, None) => CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No matching record".to_string(),
+            },
+            (_, Some(v)) => v,
+        }
+    }
+
+    // =DMAX(database, field, criteria)
+    pub(crate) fn fn_dmax(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        self.db_extreme(args, cell, true)
+    }
+
+    // =DMIN(database, field, criteria)
+    pub(crate) fn fn_dmin(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        self.db_extreme(args, cell, false)
+    }
+
+    // =DSUM(database, field, criteria)
+    pub(crate) fn fn_dsum(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        let field_col = match self.resolve_db_field_column(db_left, db_right, &args[1], cell) {
+            Ok(c) => c,
+            Err(e) => return e,
+        };
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            };
+        }
+
+        let mut sum = 0.0;
+
+        // skip header
+        let mut row = db_left.row + 1;
+        while row <= db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                let v = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                });
+                if let CalcResult::Number(n) = v {
+                    if n.is_finite() {
+                        sum += n;
+                    }
+                }
+            }
+            row += 1;
+        }
+
+        CalcResult::Number(sum)
+    }
+
+    // =DCOUNTA(database, field, criteria)
+    // Counts non-empty entries (any type) in the field for rows that match criteria
+    pub(crate) fn fn_dcounta(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        let field_col = match self.resolve_db_field_column(db_left, db_right, &args[1], cell) {
+            Ok(c) => c,
+            Err(e) => return e,
+        };
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            };
+        }
+
+        let mut count = 0;
+        for row in (db_left.row + 1)..=db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                let v = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                });
+                if !matches!(v, CalcResult::EmptyCell | CalcResult::EmptyArg) {
+                    count += 1;
+                }
+            }
+        }
+
+        CalcResult::Number(count as f64)
+    }
+
+    // =DPRODUCT(database, field, criteria)
+    pub(crate) fn fn_dproduct(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        let field_col = match self.resolve_db_field_column(db_left, db_right, &args[1], cell) {
+            Ok(c) => c,
+            Err(e) => return e,
+        };
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            };
+        }
+
+        let mut product = 1.0f64;
+        let mut has_numeric = false;
+
+        let mut row = db_left.row + 1; // skip header
+        while row <= db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                let v = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                });
+                if let CalcResult::Number(n) = v {
+                    if n.is_finite() {
+                        product *= n;
+                        has_numeric = true;
+                    }
+                }
+            }
+            row += 1;
+        }
+
+        // Excel returns 0 when no rows / no numeric values match for DPRODUCT
+        if has_numeric {
+            CalcResult::Number(product)
+        } else {
+            CalcResult::Number(0.0)
+        }
+    }
+
+    // Small internal helper for DSTDEV / DVAR
+    // Collects sum, sum of squares, and count of numeric values in the field
+    // for rows that match the criteria.
+    fn db_numeric_stats(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> Result<(f64, f64, usize), CalcResult> {
+        if args.len() != 3 {
+            return Err(CalcResult::new_args_number_error(cell));
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return Err(e),
+        };
+
+        let field_col = self.resolve_db_field_column(db_left, db_right, &args[1], cell)?;
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return Err(e),
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return Err(CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            });
+        }
+
+        let mut sum = 0.0f64;
+        let mut sumsq = 0.0f64;
+        let mut count = 0usize;
+
+        let mut row = db_left.row + 1; // skip header
+        while row <= db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                let v = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                });
+                if let CalcResult::Number(n) = v {
+                    if n.is_finite() {
+                        sum += n;
+                        sumsq += n * n;
+                        count += 1;
+                    }
+                }
+            }
+            row += 1;
+        }
+
+        Ok((sum, sumsq, count))
+    }
+
+    // =DSTDEV(database, field, criteria)
+    // Sample standard deviation of matching numeric values
+    pub(crate) fn fn_dstdev(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (sum, sumsq, count) = match self.db_numeric_stats(args, cell) {
+            Ok(stats) => stats,
+            Err(e) => return e,
+        };
+
+        // Excel behaviour: #DIV/0! if 0 or 1 numeric values match
+        if count < 2 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "Not enough numeric values matched criteria".to_string(),
+            };
+        }
+
+        let n = count as f64;
+        let var = (sumsq - (sum * sum) / n) / (n - 1.0);
+        let var = if var < 0.0 { 0.0 } else { var };
+        CalcResult::Number(var.sqrt())
+    }
+
+    // =DVAR(database, field, criteria)
+    // Sample variance of matching numeric values
+    pub(crate) fn fn_dvar(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (sum, sumsq, count) = match self.db_numeric_stats(args, cell) {
+            Ok(stats) => stats,
+            Err(e) => return e,
+        };
+
+        // Excel behaviour: #DIV/0! if 0 or 1 numeric values match
+        if count < 2 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "Not enough numeric values matched criteria".to_string(),
+            };
+        }
+
+        let n = count as f64;
+        let var = (sumsq - (sum * sum) / n) / (n - 1.0);
+        let var = if var < 0.0 { 0.0 } else { var };
+        CalcResult::Number(var)
+    }
+
+    // =DSTDEVP(database, field, criteria)
+    // Population standard deviation of matching numeric values
+    pub(crate) fn fn_dstdevp(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (sum, sumsq, count) = match self.db_numeric_stats(args, cell) {
+            Ok(stats) => stats,
+            Err(e) => return e,
+        };
+
+        // Excel behaviour: #DIV/0! if no numeric values match
+        if count == 0 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "No numeric values matched criteria".to_string(),
+            };
+        }
+
+        let n = count as f64;
+        let var = (sumsq - (sum * sum) / n) / n;
+        let var = if var < 0.0 { 0.0 } else { var };
+        CalcResult::Number(var.sqrt())
+    }
+
+    // =DVARP(database, field, criteria)
+    // Population variance of matching numeric values
+    pub(crate) fn fn_dvarp(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (sum, sumsq, count) = match self.db_numeric_stats(args, cell) {
+            Ok(stats) => stats,
+            Err(e) => return e,
+        };
+
+        // Excel behaviour: #DIV/0! if no numeric values match
+        if count == 0 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "No numeric values matched criteria".to_string(),
+            };
+        }
+
+        let n = count as f64;
+        let var = (sumsq - (sum * sum) / n) / n;
+        let var = if var < 0.0 { 0.0 } else { var };
+        CalcResult::Number(var)
+    }
+
+    /// Resolve the "field" (2nd arg) to an absolute column index (i32) within the sheet.
+    /// Field can be a number (1-based index) or a header name (case-insensitive).
+    /// Returns the absolute column index, not a 1-based offset within the database range.
+    fn resolve_db_field_column(
+        &mut self,
+        db_left: CellReferenceIndex,
+        db_right: CellReferenceIndex,
+        field_arg: &Node,
+        cell: CellReferenceIndex,
+    ) -> Result<i32, CalcResult> {
+        let field_column_name = match self.evaluate_node_in_context(field_arg, cell) {
+            CalcResult::String(s) => s.to_lowercase(),
+            CalcResult::Number(index) => {
+                let index = index.floor() as i32;
+                if index < 1 || db_left.column + index - 1 > db_right.column {
+                    return Err(CalcResult::Error {
+                        error: Error::VALUE,
+                        origin: cell,
+                        message: "Field index out of range".to_string(),
+                    });
+                }
+                return Ok(db_left.column + index - 1);
+            }
+            CalcResult::Boolean(b) => {
+                return if b {
+                    Ok(db_left.column)
+                } else {
+                    // Index 0 is out of range
+                    Err(CalcResult::Error {
+                        error: Error::VALUE,
+                        origin: cell,
+                        message: "Invalid field specifier".to_string(),
+                    })
+                };
+            }
+            error @ CalcResult::Error { .. } => {
+                return Err(error);
+            }
+            CalcResult::Range { .. } => {
+                return Err(CalcResult::Error {
+                    error: Error::NIMPL,
+                    origin: cell,
+                    message: "Arrays not supported yet".to_string(),
+                })
+            }
+            CalcResult::EmptyCell | CalcResult::EmptyArg => "".to_string(),
+            CalcResult::Array(_) => {
+                return Err(CalcResult::Error {
+                    error: Error::NIMPL,
+                    origin: cell,
+                    message: "Arrays not supported yet".to_string(),
+                })
+            }
+        };
+
+        // We search in the database a column whose header matches field_column_name
+        for column in db_left.column..=db_right.column {
+            let v = self.evaluate_cell(CellReferenceIndex {
+                sheet: db_left.sheet,
+                row: db_left.row,
+                column,
+            });
+            match &v {
+                CalcResult::String(s) => {
+                    if s.to_lowercase() == field_column_name {
+                        return Ok(column);
+                    }
+                }
+                CalcResult::Number(n) => {
+                    if field_column_name == n.to_string() {
+                        return Ok(column);
+                    }
+                }
+                CalcResult::Boolean(b) => {
+                    if field_column_name == b.to_string() {
+                        return Ok(column);
+                    }
+                }
+                CalcResult::Error { .. }
+                | CalcResult::Range { .. }
+                | CalcResult::EmptyCell
+                | CalcResult::EmptyArg
+                | CalcResult::Array(_) => {}
+            }
+        }
+
+        Err(CalcResult::Error {
+            error: Error::VALUE,
+            origin: cell,
+            message: "Field header not found".to_string(),
+        })
+    }
+
+    /// Check whether a database row matches the criteria range.
+    /// Criteria logic: OR across criteria rows; AND across columns within a row.
+    fn db_row_matches_criteria(
+        &mut self,
+        db_left: CellReferenceIndex,
+        db_right: CellReferenceIndex,
+        row: i32,
+        criteria: (CellReferenceIndex, CellReferenceIndex),
+    ) -> bool {
+        let (c_left, c_right) = criteria;
+
+        // Read criteria headers (first row of criteria range)
+        // Map header name (lowercased) -> db column (if exists)
+        let mut crit_cols: Vec<i32> = Vec::new();
+        let mut header_count = 0;
+        // We cover the criteria table:
+        //  headerA | headerB | ...
+        //  critA1  | critA2  | ...
+        //  critB1  | critB2  | ...
+        //  ...
+        for column in c_left.column..=c_right.column {
+            let cell = CellReferenceIndex {
+                sheet: c_left.sheet,
+                row: c_left.row,
+                column,
+            };
+            let criteria_header = self.evaluate_cell(cell);
+            if let Ok(s) = self.cast_to_string(criteria_header, cell) {
+                // Non-empty string header. If the header is non string we skip it
+                header_count += 1;
+                let wanted = s.to_lowercase();
+
+                // Find corresponding Database column
+                let mut found = false;
+                for db_column in db_left.column..=db_right.column {
+                    let db_header = self.evaluate_cell(CellReferenceIndex {
+                        sheet: db_left.sheet,
+                        row: db_left.row,
+                        column: db_column,
+                    });
+                    if let Ok(hs) = self.cast_to_string(db_header, cell) {
+                        if hs.to_lowercase() == wanted {
+                            crit_cols.push(db_column);
+                            found = true;
+                            break;
+                        }
+                    }
+                }
+                if !found {
+                    // that means the criteria column has no matching DB column
+                    // If the criteria condition is empty then we remove this condition
+                    // otherwise this condition can never be satisfied
+                    // We evaluate all criteria rows to see if any is non-empty
+                    let mut has_non_empty = false;
+                    for r in (c_left.row + 1)..=c_right.row {
+                        let ccell = self.evaluate_cell(CellReferenceIndex {
+                            sheet: c_left.sheet,
+                            row: r,
+                            column,
+                        });
+                        if !matches!(ccell, CalcResult::EmptyCell | CalcResult::EmptyArg) {
+                            has_non_empty = true;
+                            break;
+                        }
+                    }
+                    if has_non_empty {
+                        // This criteria column can never be satisfied
+                        header_count -= 1;
+                    }
+                }
+            };
+        }
+
+        if c_right.row <= c_left.row {
+            // If no criteria rows (only headers), everything matches
+            return true;
+        }
+
+        if header_count == 0 {
+            // If there are not "String" headers, nothing matches
+            // NB: There might be String headers that do not match any DB columns,
+            // in that case everything matches.
+            return false;
+        }
+
+        // Evaluate each criteria row (OR)
+        for r in (c_left.row + 1)..=c_right.row {
+            // AND across columns for this criteria row
+            let mut and_ok = true;
+
+            for (offset, db_col) in crit_cols.iter().enumerate() {
+                // Criteria cell
+                let ccell = self.evaluate_cell(CellReferenceIndex {
+                    sheet: c_left.sheet,
+                    row: r,
+                    column: c_left.column + offset as i32,
+                });
+
+                // Empty criteria cell -> ignored
+                if matches!(ccell, CalcResult::EmptyCell | CalcResult::EmptyArg) {
+                    continue;
+                }
+
+                // Database value for this row/column
+                let db_val = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: *db_col,
+                });
+
+                if !self.criteria_cell_matches(&db_val, &ccell) {
+                    and_ok = false;
+                    break;
+                }
+            }
+
+            if and_ok {
+                // This criteria row satisfied (OR)
+                return true;
+            }
+        }
+
+        // none matched
+        false
+    }
+
+    /// Implements Excel-like criteria matching for a single value.
+    /// Supports prefixes: <>, >=, <=, >, <, = ; wildcards * and ? for string equals.
+    fn criteria_cell_matches(&self, db_val: &CalcResult, crit_cell: &CalcResult) -> bool {
+        // Convert the criteria cell to a string for operator parsing if possible,
+        // otherwise fall back to equality via compare_values.
+
+        let mut criteria = match crit_cell {
+            CalcResult::String(s) => s.trim().to_string(),
+            CalcResult::Number(n) => {
+                // treat as equality with number
+                return match db_val {
+                    CalcResult::Number(v) => (*v - *n).abs() <= f64::EPSILON,
+                    _ => false,
+                };
+            }
+            CalcResult::Boolean(b) => {
+                // check equality with boolean
+                return match db_val {
+                    CalcResult::Boolean(v) => *v == *b,
+                    _ => false,
+                };
+            }
+            CalcResult::EmptyCell | CalcResult::EmptyArg => "".to_string(),
+            CalcResult::Error { .. } => return false,
+            CalcResult::Range { .. } | CalcResult::Array(_) => return false,
+        };
+
+        // Detect operator prefix
+        let mut op = "="; // default equality (with wildcard semantics for strings)
+        let prefixes = ["<>", ">=", "<=", ">", "<", "="];
+        for p in prefixes.iter() {
+            if criteria.starts_with(p) {
+                op = p;
+                criteria = criteria[p.len()..].trim().to_string();
+                break;
+            }
+        }
+
+        // Is it a number?
+        let rhs_num = criteria.parse::<f64>().ok();
+
+        // Is it a date?
+        // FIXME: We should parse dates according to locale settings
+        let rhs_date = criteria.parse::<chrono::NaiveDate>().ok();
+
+        match op {
+            ">" | ">=" | "<" | "<=" => {
+                if let Some(d) = rhs_date {
+                    // date comparison
+                    let serial = match date_to_serial_number(d.day(), d.month(), d.year()) {
+                        Ok(sn) => sn as f64,
+                        Err(_) => return false,
+                    };
+
+                    if let CalcResult::Number(n) = db_val {
+                        match op {
+                            ">" => *n > serial,
+                            ">=" => *n >= serial,
+                            "<" => *n < serial,
+                            "<=" => *n <= serial,
+                            _ => false,
+                        }
+                    } else {
+                        false
+                    }
+                } else if let Some(t) = rhs_num {
+                    // numeric comparison
+                    if let CalcResult::Number(n) = db_val {
+                        match op {
+                            ">" => *n > t,
+                            ">=" => *n >= t,
+                            "<" => *n < t,
+                            "<=" => *n <= t,
+                            _ => false,
+                        }
+                    } else {
+                        false
+                    }
+                } else {
+                    // string comparison (case-insensitive) using compare_values semantics
+                    let rhs = CalcResult::String(criteria.to_lowercase());
+                    let lhs = match db_val {
+                        CalcResult::String(s) => CalcResult::String(s.to_lowercase()),
+                        x => x.clone(),
+                    };
+                    let c = compare_values(&lhs, &rhs);
+                    match op {
+                        ">" => c > 0,
+                        ">=" => c >= 0,
+                        "<" => c < 0,
+                        "<=" => c <= 0,
+                        _ => false,
+                    }
+                }
+            }
+            "<>" => {
+                // not equal (with wildcard semantics for strings)
+                // If rhs has wildcards and db_val is string, do regex; else use compare_values != 0
+                if let CalcResult::String(s) = db_val {
+                    if criteria.contains('*') || criteria.contains('?') {
+                        if let Ok(re) = from_wildcard_to_regex(&criteria.to_lowercase(), true) {
+                            return !result_matches_regex(
+                                &CalcResult::String(s.to_lowercase()),
+                                &re,
+                            );
+                        }
+                    }
+                }
+                let rhs = if let Some(n) = rhs_num {
+                    CalcResult::Number(n)
+                } else {
+                    CalcResult::String(criteria.to_lowercase())
+                };
+                let lhs = match db_val {
+                    CalcResult::String(s) => CalcResult::String(s.to_lowercase()),
+                    x => x.clone(),
+                };
+                compare_values(&lhs, &rhs) != 0
+            }
+            _ => {
+                // equality. For strings, support wildcards (*, ?)
+                if let Some(n) = rhs_num {
+                    // numeric equals
+                    if let CalcResult::Number(m) = db_val {
+                        (*m - n).abs() <= f64::EPSILON
+                    } else {
+                        compare_values(db_val, &CalcResult::Number(n)) == 0
+                    }
+                } else {
+                    // textual/boolean equals (case-insensitive), wildcard-enabled for strings
+                    if let CalcResult::String(s) = db_val {
+                        if criteria.contains('*') || criteria.contains('?') {
+                            if let Ok(re) = from_wildcard_to_regex(&criteria.to_lowercase(), true) {
+                                return result_matches_regex(
+                                    &CalcResult::String(s.to_lowercase()),
+                                    &re,
+                                );
+                            }
+                        }
+                        // This is weird but we only need to check if "starts with" for equality
+                        return s.to_lowercase().starts_with(&criteria.to_lowercase());
+                    }
+                    // Fallback: compare_values equality
+                    compare_values(db_val, &CalcResult::String(criteria.to_lowercase())) == 0
+                }
+            }
+        }
+    }
+
+    /// Shared implementation for DMAX/DMIN
+    fn db_extreme(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+        want_max: bool,
+    ) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let (db_left, db_right) = match self.get_reference(&args[0], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        let field_col = match self.resolve_db_field_column(db_left, db_right, &args[1], cell) {
+            Ok(c) => c,
+            Err(e) => return e,
+        };
+
+        let criteria = match self.get_reference(&args[2], cell) {
+            Ok(r) => (r.left, r.right),
+            Err(e) => return e,
+        };
+
+        if db_right.row <= db_left.row {
+            // no data rows
+            return CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "No data rows in database".to_string(),
+            };
+        }
+
+        let mut best: Option<f64> = None;
+
+        let mut row = db_left.row + 1;
+        while row <= db_right.row {
+            if self.db_row_matches_criteria(db_left, db_right, row, criteria) {
+                let v = self.evaluate_cell(CellReferenceIndex {
+                    sheet: db_left.sheet,
+                    row,
+                    column: field_col,
+                });
+                if let CalcResult::Number(value) = v {
+                    if value.is_finite() {
+                        best = Some(match best {
+                            None => value,
+                            Some(cur) => {
+                                if want_max {
+                                    value.max(cur)
+                                } else {
+                                    value.min(cur)
+                                }
+                            }
+                        });
+                    }
+                }
+            }
+            row += 1;
+        }
+
+        match best {
+            Some(v) => CalcResult::Number(v),
+            None => CalcResult::Number(0.0),
+        }
+    }
+}

base/src/functions/engineering/bessel.rs

@@ -1,10 +1,12 @@
+use statrs::function::erf::{erf, erfc};
+
 use crate::{
     calc_result::CalcResult,
     expressions::{parser::Node, token::Error, types::CellReferenceIndex},
     model::Model,
 };
 
-use super::transcendental::{bessel_i, bessel_j, bessel_k, bessel_y, erf};
+use super::transcendental::{bessel_i, bessel_j, bessel_k, bessel_y};
 // https://root.cern/doc/v610/TMath_8cxx_source.html
 
 // Notice that the parameters for Bessel functions in Excel and here have inverted order
@@ -160,7 +162,7 @@ impl Model {
             Ok(f) => f,
             Err(s) => return s,
         };
-        CalcResult::Number(1.0 - erf(x))
+        CalcResult::Number(erfc(x))
     }
 
     pub(crate) fn fn_erfcprecise(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
@@ -171,6 +173,6 @@ impl Model {
             Ok(f) => f,
             Err(s) => return s,
         };
-        CalcResult::Number(1.0 - erf(x))
+        CalcResult::Number(erfc(x))
     }
 }

base/src/functions/engineering/transcendental/erf.rs

@@ -1,53 +0,0 @@
-pub(crate) fn erf(x: f64) -> f64 {
-    let cof = vec![
-        -1.3026537197817094,
-        6.419_697_923_564_902e-1,
-        1.9476473204185836e-2,
-        -9.561_514_786_808_63e-3,
-        -9.46595344482036e-4,
-        3.66839497852761e-4,
-        4.2523324806907e-5,
-        -2.0278578112534e-5,
-        -1.624290004647e-6,
-        1.303655835580e-6,
-        1.5626441722e-8,
-        -8.5238095915e-8,
-        6.529054439e-9,
-        5.059343495e-9,
-        -9.91364156e-10,
-        -2.27365122e-10,
-        9.6467911e-11,
-        2.394038e-12,
-        -6.886027e-12,
-        8.94487e-13,
-        3.13092e-13,
-        -1.12708e-13,
-        3.81e-16,
-        7.106e-15,
-        -1.523e-15,
-        -9.4e-17,
-        1.21e-16,
-        -2.8e-17,
-    ];
-
-    let mut d = 0.0;
-    let mut dd = 0.0;
-
-    let x_abs = x.abs();
-
-    let t = 2.0 / (2.0 + x_abs);
-    let ty = 4.0 * t - 2.0;
-
-    for j in (1..=cof.len() - 1).rev() {
-        let tmp = d;
-        d = ty * d - dd + cof[j];
-        dd = tmp;
-    }
-
-    let res = t * f64::exp(-x_abs * x_abs + 0.5 * (cof[0] + ty * d) - dd);
-    if x < 0.0 {
-        res - 1.0
-    } else {
-        1.0 - res
-    }
-}

base/src/functions/engineering/transcendental/mod.rs

@@ -4,7 +4,6 @@ mod bessel_j1_y1;
 mod bessel_jn_yn;
 mod bessel_k;
 mod bessel_util;
-mod erf;
 
 #[cfg(test)]
 mod test_bessel;
@@ -13,4 +12,3 @@ pub(crate) use bessel_i::bessel_i;
 pub(crate) use bessel_jn_yn::jn as bessel_j;
 pub(crate) use bessel_jn_yn::yn as bessel_y;
 pub(crate) use bessel_k::bessel_k;
-pub(crate) use erf::erf;

base/src/functions/information.rs

@@ -1,6 +1,6 @@
 use crate::{
     calc_result::CalcResult,
-    expressions::{parser::Node, token::Error, types::CellReferenceIndex},
+    expressions::{parser::Node, token::Error, types::CellReferenceIndex, utils::number_to_column},
     model::{Model, ParsedDefinedName},
 };
 
@@ -320,4 +320,150 @@ impl Model {
             message: "Invalid name".to_string(),
         }
     }
+
+    pub(crate) fn fn_n(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let arg_count = args.len();
+        if arg_count != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let value = match self.evaluate_node_in_context(&args[0], cell) {
+            CalcResult::Number(n) => n,
+            CalcResult::String(_) => 0.0,
+            CalcResult::Boolean(f) => {
+                if f {
+                    1.0
+                } else {
+                    0.0
+                }
+            }
+            CalcResult::EmptyCell | CalcResult::EmptyArg => 0.0,
+            error @ CalcResult::Error { .. } => return error,
+            CalcResult::Range { .. } => {
+                return CalcResult::Error {
+                    error: Error::NIMPL,
+                    origin: cell,
+                    message: "Arrays not supported yet".to_string(),
+                }
+            }
+            CalcResult::Array(_) => {
+                return CalcResult::Error {
+                    error: Error::NIMPL,
+                    origin: cell,
+                    message: "Arrays not supported yet".to_string(),
+                }
+            }
+        };
+
+        CalcResult::Number(value)
+    }
+
+    pub(crate) fn fn_sheets(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let arg_count = args.len();
+        if arg_count > 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        if arg_count == 1 {
+            return CalcResult::Error {
+                error: Error::NIMPL,
+                origin: cell,
+                message: "Sheets function with an argument is not implemented".to_string(),
+            };
+        }
+        let sheet_count = self.workbook.worksheets.len() as f64;
+        CalcResult::Number(sheet_count)
+    }
+
+    pub(crate) fn fn_cell(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let arg_count = args.len();
+        if arg_count == 0 || arg_count > 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let reference = if arg_count == 2 {
+            match self.evaluate_node_with_reference(&args[1], cell) {
+                CalcResult::Range { left, right: _ } => {
+                    // we just take the left cell of the range
+                    left
+                }
+                _ => {
+                    return CalcResult::Error {
+                        error: Error::VALUE,
+                        origin: cell,
+                        message: "Argument must be a reference".to_string(),
+                    }
+                }
+            }
+        } else {
+            CellReferenceIndex {
+                sheet: cell.sheet,
+                row: cell.row,
+                column: cell.column,
+            }
+        };
+        let info_type = match self.get_string(&args[0], cell) {
+            Ok(s) => s.to_uppercase(),
+            Err(e) => return e,
+        };
+        match info_type.as_str() {
+            "ADDRESS" => {
+                if reference.sheet != cell.sheet {
+                    return CalcResult::Error {
+                        error: Error::NIMPL,
+                        origin: cell,
+                        message: "References to other sheets not implemented".to_string(),
+                    };
+                }
+                let column = match number_to_column(reference.column) {
+                    Some(c) => c,
+                    None => {
+                        return CalcResult::Error {
+                            error: Error::VALUE,
+                            origin: cell,
+                            message: "Invalid column".to_string(),
+                        }
+                    }
+                };
+                let address = format!("${}${}", column, reference.row);
+                CalcResult::String(address)
+            }
+            "COL" => CalcResult::Number(reference.column as f64),
+            "COLOR" | "FILENAME" | "FORMAT" | "PARENTHESES" | "PREFIX" | "PROTECT" | "WIDTH" => {
+                CalcResult::Error {
+                    error: Error::VALUE,
+                    origin: cell,
+                    message: "info_type not implemented".to_string(),
+                }
+            }
+            "CONTENTS" => self.evaluate_cell(reference),
+            "ROW" => CalcResult::Number(reference.row as f64),
+            "TYPE" => {
+                let cell_type = match self.evaluate_cell(reference) {
+                    CalcResult::EmptyCell => "b",
+                    CalcResult::String(_) => "l",
+                    CalcResult::Number(_) => "v",
+                    CalcResult::Boolean(_) => "v",
+                    CalcResult::Error { .. } => "v",
+                    CalcResult::Range { .. } => "v",
+                    CalcResult::EmptyArg => "v",
+                    CalcResult::Array(_) => "v",
+                };
+                CalcResult::String(cell_type.to_string())
+            }
+            _ => CalcResult::Error {
+                error: Error::VALUE,
+                origin: cell,
+                message: "Invalid info_type".to_string(),
+            },
+        }
+    }
+
+    pub(crate) fn fn_info(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() || args.len() > 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        CalcResult::Error {
+            error: Error::NIMPL,
+            origin: cell,
+            message: "Info function not implemented".to_string(),
+        }
+    }
 }

base/src/functions/macros.rs

@@ -68,14 +68,14 @@ macro_rules! single_number_fn {
                                 },
                                 // If String, parse to f64 then apply or #VALUE! error
                                 ArrayNode::String(s) => {
-                                    let node = match s.parse::<f64>() {
-                                        Ok(f) => match $op(f) {
+                                    let node = match self.cast_number(&s) {
+                                        Some(f) => match $op(f) {
                                             Ok(x) => ArrayNode::Number(x),
                                             Err(Error::DIV) => ArrayNode::Error(Error::DIV),
                                             Err(Error::VALUE) => ArrayNode::Error(Error::VALUE),
                                             Err(e) => ArrayNode::Error(e),
                                         },
-                                        Err(_) => ArrayNode::Error(Error::VALUE),
+                                        None => ArrayNode::Error(Error::VALUE),
                                     };
                                     data_row.push(node);
                                 }

base/src/functions/math_util.rs

@@ -0,0 +1,200 @@
+/// Parse Roman (classic or Excel variants) → number
+pub fn from_roman(s: &str) -> Result<u32, String> {
+    if s.is_empty() {
+        return Err("empty numeral".into());
+    }
+    fn val(c: char) -> Option<u32> {
+        Some(match c {
+            'I' => 1,
+            'V' => 5,
+            'X' => 10,
+            'L' => 50,
+            'C' => 100,
+            'D' => 500,
+            'M' => 1000,
+            _ => return None,
+        })
+    }
+
+    // Accept the union of subtractive pairs used by the tables above (Excel-compatible).
+    fn allowed_subtractive(a: char, b: char) -> bool {
+        matches!(
+            (a, b),
+            // classic:
+            ('I','V')|('I','X')|('X','L')|('X','C')|('C','D')|('C','M')
+            // Excel forms:
+            |('V','L')|('L','D')|('L','M') // VL, LD, LM
+            |('X','D')|('X','M')          // XD, XM
+            |('V','M')                    // VM
+            |('I','L')|('I','C')|('I','D')|('I','M') // IL, IC, ID, IM
+            |('V','D')|('V','C') // VD, VC
+        )
+    }
+
+    let chars: Vec<char> = s.chars().map(|c| c.to_ascii_uppercase()).collect();
+    let mut total = 0u32;
+    let mut i = 0usize;
+
+    // Repetition rules similar to classic Romans:
+    // V, L, D cannot repeat; I, X, C, M max 3 in a row.
+    let mut last_char: Option<char> = None;
+    let mut run_len = 0usize;
+
+    while i < chars.len() {
+        let c = chars[i];
+        let v = val(c).ok_or_else(|| format!("invalid character '{c}'"))?;
+
+        if Some(c) == last_char {
+            run_len += 1;
+            match c {
+                'V' | 'L' | 'D' => return Err(format!("invalid repetition of '{c}'")),
+                _ if run_len >= 3 => return Err(format!("invalid repetition of '{c}'")),
+                _ => {}
+            }
+        } else {
+            last_char = Some(c);
+            run_len = 0;
+        }
+
+        if i + 1 < chars.len() {
+            let c2 = chars[i + 1];
+            let v2 = val(c2).ok_or_else(|| format!("invalid character '{c2}'"))?;
+            if v < v2 {
+                if !allowed_subtractive(c, c2) {
+                    return Err(format!("invalid subtractive pair '{c}{c2}'"));
+                }
+                // Disallow stacked subtractives like IIV, XXL:
+                if run_len > 0 {
+                    return Err(format!("malformed numeral near position {i}"));
+                }
+                total += v2 - v;
+                i += 2;
+                last_char = None;
+                run_len = 0;
+                continue;
+            }
+        }
+
+        total += v;
+        i += 1;
+    }
+    Ok(total)
+}
+
+/// Classic Roman (strict) encoder used as a base for all forms.
+fn to_roman(mut n: u32) -> Result<String, String> {
+    if !(1..=3999).contains(&n) {
+        return Err("value out of range (must be 1..=3999)".into());
+    }
+
+    const MAP: &[(u32, &str)] = &[
+        (1000, "M"),
+        (900, "CM"),
+        (500, "D"),
+        (400, "CD"),
+        (100, "C"),
+        (90, "XC"),
+        (50, "L"),
+        (40, "XL"),
+        (10, "X"),
+        (9, "IX"),
+        (5, "V"),
+        (4, "IV"),
+        (1, "I"),
+    ];
+
+    let mut out = String::with_capacity(15);
+    for &(val, sym) in MAP {
+        while n >= val {
+            out.push_str(sym);
+            n -= val;
+        }
+        if n == 0 {
+            break;
+        }
+    }
+    Ok(out)
+}
+
+/// Excel/Google Sheets compatible ROMAN(number, [form]) encoder.
+/// `form`: 0..=4 (0=Classic, 4=Simplified).
+pub fn to_roman_with_form(n: u32, form: i32) -> Result<String, String> {
+    let mut s = to_roman(n)?;
+    if form == 0 {
+        return Ok(s);
+    }
+    if !(0..=4).contains(&form) {
+        return Err("form must be between 0 and 4".into());
+    }
+
+    // Base rules (apply for all f >= 1)
+    let base_rules: &[(&str, &str)] = &[
+        // C(D|M)XC -> L$1XL
+        ("CDXC", "LDXL"),
+        ("CMXC", "LMXL"),
+        // C(D|M)L -> L$1
+        ("CDL", "LD"),
+        ("CML", "LM"),
+        // X(L|C)IX -> V$1IV
+        ("XLIX", "VLIV"),
+        ("XCIX", "VCIV"),
+        // X(L|C)V -> V$1
+        ("XLV", "VL"),
+        ("XCV", "VC"),
+    ];
+
+    // Level 2 extra rules
+    let lvl2_rules: &[(&str, &str)] = &[
+        // V(L|C)IV -> I$1
+        ("VLIV", "IL"),
+        ("VCIV", "IC"),
+        // L(D|M)XL -> X$1
+        ("LDXL", "XD"),
+        ("LMXL", "XM"),
+        // L(D|M)VL -> X$1V
+        ("LDVL", "XDV"),
+        ("LMVL", "XMV"),
+        // L(D|M)IL -> X$1IX
+        ("LDIL", "XDIX"),
+        ("LMIL", "XMIX"),
+    ];
+
+    // Level 3 extra rules
+    let lvl3_rules: &[(&str, &str)] = &[
+        // X(D|M)V -> V$1
+        ("XDV", "VD"),
+        ("XMV", "VM"),
+        // X(D|M)IX -> V$1IV
+        ("XDIX", "VDIV"),
+        ("XMIX", "VMIV"),
+    ];
+
+    // Level 4 extra rules
+    let lvl4_rules: &[(&str, &str)] = &[
+        // V(D|M)IV -> I$1
+        ("VDIV", "ID"),
+        ("VMIV", "IM"),
+    ];
+
+    // Helper to apply a batch of (from -> to) globally, in order.
+    fn apply_rules(mut t: String, rules: &[(&str, &str)]) -> String {
+        for (from, to) in rules {
+            if t.contains(from) {
+                t = t.replace(from, to);
+            }
+        }
+        t
+    }
+
+    s = apply_rules(s, base_rules);
+    if form >= 2 {
+        s = apply_rules(s, lvl2_rules);
+    }
+    if form >= 3 {
+        s = apply_rules(s, lvl3_rules);
+    }
+    if form >= 4 {
+        s = apply_rules(s, lvl4_rules);
+    }
+    Ok(s)
+}

base/src/functions/mathematical_sum.rs

@@ -0,0 +1,230 @@
+use crate::expressions::types::CellReferenceIndex;
+
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+type TwoMatricesResult = (i32, i32, Vec<Option<f64>>, Vec<Option<f64>>);
+
+// Helper to check if two shapes are the same or compatible 1D shapes
+fn is_same_shape_or_1d(rows1: i32, cols1: i32, rows2: i32, cols2: i32) -> bool {
+    (rows1 == rows2 && cols1 == cols2)
+        || (rows1 == 1 && cols2 == 1 && cols1 == rows2)
+        || (rows2 == 1 && cols1 == 1 && cols2 == rows1)
+}
+
+impl Model {
+    // SUMX2MY2(array_x, array_y) - Returns the sum of the difference of squares
+    pub(crate) fn fn_sumx2my2(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let result = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(s) => return s,
+        };
+
+        let (_, _, values_left, values_right) = result;
+
+        let mut sum = 0.0;
+        for (x_opt, y_opt) in values_left.into_iter().zip(values_right.into_iter()) {
+            let x = x_opt.unwrap_or(0.0);
+            let y = y_opt.unwrap_or(0.0);
+            sum += x * x - y * y;
+        }
+
+        CalcResult::Number(sum)
+    }
+
+    // SUMX2PY2(array_x, array_y) - Returns the sum of the sum of squares
+    pub(crate) fn fn_sumx2py2(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let result = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(s) => return s,
+        };
+
+        let (_rows, _cols, values_left, values_right) = result;
+
+        let mut sum = 0.0;
+        for (x_opt, y_opt) in values_left.into_iter().zip(values_right.into_iter()) {
+            let x = x_opt.unwrap_or(0.0);
+            let y = y_opt.unwrap_or(0.0);
+            sum += x * x + y * y;
+        }
+
+        CalcResult::Number(sum)
+    }
+
+    // SUMXMY2(array_x, array_y) - Returns the sum of squares of differences
+    pub(crate) fn fn_sumxmy2(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let result = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(s) => return s,
+        };
+
+        let (_, _, values_left, values_right) = result;
+
+        let mut sum = 0.0;
+        for (x_opt, y_opt) in values_left.into_iter().zip(values_right.into_iter()) {
+            let x = x_opt.unwrap_or(0.0);
+            let y = y_opt.unwrap_or(0.0);
+            let diff = x - y;
+            sum += diff * diff;
+        }
+
+        CalcResult::Number(sum)
+    }
+
+    // Helper function to extract and validate two matrices (ranges or arrays) with compatible shapes.
+    // Returns (rows, cols, values_left, values_right) or an error.
+    pub(crate) fn fn_get_two_matrices(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> Result<TwoMatricesResult, CalcResult> {
+        if args.len() != 2 {
+            return Err(CalcResult::new_args_number_error(cell));
+        }
+        let x_range = self.evaluate_node_in_context(&args[0], cell);
+        let y_range = self.evaluate_node_in_context(&args[1], cell);
+
+        let result = match (x_range, y_range) {
+            (
+                CalcResult::Range {
+                    left: l1,
+                    right: r1,
+                },
+                CalcResult::Range {
+                    left: l2,
+                    right: r2,
+                },
+            ) => {
+                if l1.sheet != l2.sheet {
+                    return Err(CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Ranges are in different sheets".to_string(),
+                    ));
+                }
+                let rows1 = r1.row - l1.row + 1;
+                let cols1 = r1.column - l1.column + 1;
+                let rows2 = r2.row - l2.row + 1;
+                let cols2 = r2.column - l2.column + 1;
+                if !is_same_shape_or_1d(rows1, cols1, rows2, cols2) {
+                    return Err(CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Ranges must be of the same shape".to_string(),
+                    ));
+                }
+                let values_left = self.values_from_range(l1, r1)?;
+                let values_right = self.values_from_range(l2, r2)?;
+                (rows1, cols1, values_left, values_right)
+            }
+            (
+                CalcResult::Array(left),
+                CalcResult::Range {
+                    left: l2,
+                    right: r2,
+                },
+            ) => {
+                let rows2 = r2.row - l2.row + 1;
+                let cols2 = r2.column - l2.column + 1;
+
+                let rows1 = left.len() as i32;
+                let cols1 = if rows1 > 0 { left[0].len() as i32 } else { 0 };
+                if !is_same_shape_or_1d(rows1, cols1, rows2, cols2) {
+                    return Err(CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Array and range must be of the same shape".to_string(),
+                    ));
+                }
+                let values_left = match self.values_from_array(left) {
+                    Err(error) => {
+                        return Err(CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            format!("Error in first array: {:?}", error),
+                        ));
+                    }
+                    Ok(v) => v,
+                };
+                let values_right = self.values_from_range(l2, r2)?;
+                (rows2, cols2, values_left, values_right)
+            }
+            (
+                CalcResult::Range {
+                    left: l1,
+                    right: r1,
+                },
+                CalcResult::Array(right),
+            ) => {
+                let rows1 = r1.row - l1.row + 1;
+                let cols1 = r1.column - l1.column + 1;
+
+                let rows2 = right.len() as i32;
+                let cols2 = if rows2 > 0 { right[0].len() as i32 } else { 0 };
+                if !is_same_shape_or_1d(rows1, cols1, rows2, cols2) {
+                    return Err(CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Range and array must be of the same shape".to_string(),
+                    ));
+                }
+                let values_left = self.values_from_range(l1, r1)?;
+                let values_right = match self.values_from_array(right) {
+                    Err(error) => {
+                        return Err(CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            format!("Error in second array: {:?}", error),
+                        ));
+                    }
+                    Ok(v) => v,
+                };
+                (rows1, cols1, values_left, values_right)
+            }
+            (CalcResult::Array(left), CalcResult::Array(right)) => {
+                let rows1 = left.len() as i32;
+                let rows2 = right.len() as i32;
+                let cols1 = if rows1 > 0 { left[0].len() as i32 } else { 0 };
+                let cols2 = if rows2 > 0 { right[0].len() as i32 } else { 0 };
+
+                if !is_same_shape_or_1d(rows1, cols1, rows2, cols2) {
+                    return Err(CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Arrays must be of the same shape".to_string(),
+                    ));
+                }
+                let values_left = match self.values_from_array(left) {
+                    Err(error) => {
+                        return Err(CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            format!("Error in first array: {:?}", error),
+                        ));
+                    }
+                    Ok(v) => v,
+                };
+                let values_right = match self.values_from_array(right) {
+                    Err(error) => {
+                        return Err(CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            format!("Error in second array: {:?}", error),
+                        ));
+                    }
+                    Ok(v) => v,
+                };
+                (rows1, cols1, values_left, values_right)
+            }
+            _ => {
+                return Err(CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Both arguments must be ranges or arrays".to_string(),
+                ));
+            }
+        };
+        Ok(result)
+    }
+}

base/src/functions/statistical.rs

@@ -1,733 +0,0 @@
-use crate::constants::{LAST_COLUMN, LAST_ROW};
-use crate::expressions::types::CellReferenceIndex;
-use crate::{
-    calc_result::{CalcResult, Range},
-    expressions::parser::Node,
-    expressions::token::Error,
-    model::Model,
-};
-
-use super::util::build_criteria;
-
-impl Model {
-    pub(crate) fn fn_average(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        if args.is_empty() {
-            return CalcResult::new_args_number_error(cell);
-        }
-        let mut count = 0.0;
-        let mut sum = 0.0;
-        for arg in args {
-            match self.evaluate_node_in_context(arg, cell) {
-                CalcResult::Number(value) => {
-                    count += 1.0;
-                    sum += value;
-                }
-                CalcResult::Boolean(b) => {
-                    if let Node::ReferenceKind { .. } = arg {
-                    } else {
-                        sum += if b { 1.0 } else { 0.0 };
-                        count += 1.0;
-                    }
-                }
-                CalcResult::Range { left, right } => {
-                    if left.sheet != right.sheet {
-                        return CalcResult::new_error(
-                            Error::VALUE,
-                            cell,
-                            "Ranges are in different sheets".to_string(),
-                        );
-                    }
-                    for row in left.row..(right.row + 1) {
-                        for column in left.column..(right.column + 1) {
-                            match self.evaluate_cell(CellReferenceIndex {
-                                sheet: left.sheet,
-                                row,
-                                column,
-                            }) {
-                                CalcResult::Number(value) => {
-                                    count += 1.0;
-                                    sum += value;
-                                }
-                                error @ CalcResult::Error { .. } => return error,
-                                CalcResult::Range { .. } => {
-                                    return CalcResult::new_error(
-                                        Error::ERROR,
-                                        cell,
-                                        "Unexpected Range".to_string(),
-                                    );
-                                }
-                                _ => {}
-                            }
-                        }
-                    }
-                }
-                error @ CalcResult::Error { .. } => return error,
-                CalcResult::String(s) => {
-                    if let Node::ReferenceKind { .. } = arg {
-                        // Do nothing
-                    } else if let Ok(t) = s.parse::<f64>() {
-                        sum += t;
-                        count += 1.0;
-                    } else {
-                        return CalcResult::Error {
-                            error: Error::VALUE,
-                            origin: cell,
-                            message: "Argument cannot be cast into number".to_string(),
-                        };
-                    }
-                }
-                _ => {
-                    // Ignore everything else
-                }
-            };
-        }
-        if count == 0.0 {
-            return CalcResult::Error {
-                error: Error::DIV,
-                origin: cell,
-                message: "Division by Zero".to_string(),
-            };
-        }
-        CalcResult::Number(sum / count)
-    }
-
-    pub(crate) fn fn_averagea(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        if args.is_empty() {
-            return CalcResult::new_args_number_error(cell);
-        }
-        let mut count = 0.0;
-        let mut sum = 0.0;
-        for arg in args {
-            match self.evaluate_node_in_context(arg, cell) {
-                CalcResult::Range { left, right } => {
-                    if left.sheet != right.sheet {
-                        return CalcResult::new_error(
-                            Error::VALUE,
-                            cell,
-                            "Ranges are in different sheets".to_string(),
-                        );
-                    }
-                    for row in left.row..(right.row + 1) {
-                        for column in left.column..(right.column + 1) {
-                            match self.evaluate_cell(CellReferenceIndex {
-                                sheet: left.sheet,
-                                row,
-                                column,
-                            }) {
-                                CalcResult::String(_) => count += 1.0,
-                                CalcResult::Number(value) => {
-                                    count += 1.0;
-                                    sum += value;
-                                }
-                                CalcResult::Boolean(b) => {
-                                    if b {
-                                        sum += 1.0;
-                                    }
-                                    count += 1.0;
-                                }
-                                error @ CalcResult::Error { .. } => return error,
-                                CalcResult::Range { .. } => {
-                                    return CalcResult::new_error(
-                                        Error::ERROR,
-                                        cell,
-                                        "Unexpected Range".to_string(),
-                                    );
-                                }
-                                CalcResult::EmptyCell | CalcResult::EmptyArg => {}
-                                CalcResult::Array(_) => {
-                                    return CalcResult::Error {
-                                        error: Error::NIMPL,
-                                        origin: cell,
-                                        message: "Arrays not supported yet".to_string(),
-                                    }
-                                }
-                            }
-                        }
-                    }
-                }
-                CalcResult::Number(value) => {
-                    count += 1.0;
-                    sum += value;
-                }
-                CalcResult::String(s) => {
-                    if let Node::ReferenceKind { .. } = arg {
-                        // Do nothing
-                        count += 1.0;
-                    } else if let Ok(t) = s.parse::<f64>() {
-                        sum += t;
-                        count += 1.0;
-                    } else {
-                        return CalcResult::Error {
-                            error: Error::VALUE,
-                            origin: cell,
-                            message: "Argument cannot be cast into number".to_string(),
-                        };
-                    }
-                }
-                CalcResult::Boolean(b) => {
-                    count += 1.0;
-                    if b {
-                        sum += 1.0;
-                    }
-                }
-                error @ CalcResult::Error { .. } => return error,
-                CalcResult::EmptyCell | CalcResult::EmptyArg => {}
-                CalcResult::Array(_) => {
-                    return CalcResult::Error {
-                        error: Error::NIMPL,
-                        origin: cell,
-                        message: "Arrays not supported yet".to_string(),
-                    }
-                }
-            };
-        }
-        if count == 0.0 {
-            return CalcResult::Error {
-                error: Error::DIV,
-                origin: cell,
-                message: "Division by Zero".to_string(),
-            };
-        }
-        CalcResult::Number(sum / count)
-    }
-
-    pub(crate) fn fn_count(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        if args.is_empty() {
-            return CalcResult::new_args_number_error(cell);
-        }
-        let mut result = 0.0;
-        for arg in args {
-            match self.evaluate_node_in_context(arg, cell) {
-                CalcResult::Number(_) => {
-                    result += 1.0;
-                }
-                CalcResult::Boolean(_) => {
-                    if !matches!(arg, Node::ReferenceKind { .. }) {
-                        result += 1.0;
-                    }
-                }
-                CalcResult::String(s) => {
-                    if !matches!(arg, Node::ReferenceKind { .. }) && s.parse::<f64>().is_ok() {
-                        result += 1.0;
-                    }
-                }
-                CalcResult::Range { left, right } => {
-                    if left.sheet != right.sheet {
-                        return CalcResult::new_error(
-                            Error::VALUE,
-                            cell,
-                            "Ranges are in different sheets".to_string(),
-                        );
-                    }
-                    for row in left.row..(right.row + 1) {
-                        for column in left.column..(right.column + 1) {
-                            if let CalcResult::Number(_) = self.evaluate_cell(CellReferenceIndex {
-                                sheet: left.sheet,
-                                row,
-                                column,
-                            }) {
-                                result += 1.0;
-                            }
-                        }
-                    }
-                }
-                _ => {
-                    // Ignore everything else
-                }
-            };
-        }
-        CalcResult::Number(result)
-    }
-
-    pub(crate) fn fn_counta(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        if args.is_empty() {
-            return CalcResult::new_args_number_error(cell);
-        }
-        let mut result = 0.0;
-        for arg in args {
-            match self.evaluate_node_in_context(arg, cell) {
-                CalcResult::EmptyCell | CalcResult::EmptyArg => {}
-                CalcResult::Range { left, right } => {
-                    if left.sheet != right.sheet {
-                        return CalcResult::new_error(
-                            Error::VALUE,
-                            cell,
-                            "Ranges are in different sheets".to_string(),
-                        );
-                    }
-                    for row in left.row..(right.row + 1) {
-                        for column in left.column..(right.column + 1) {
-                            match self.evaluate_cell(CellReferenceIndex {
-                                sheet: left.sheet,
-                                row,
-                                column,
-                            }) {
-                                CalcResult::EmptyCell | CalcResult::EmptyArg => {}
-                                _ => {
-                                    result += 1.0;
-                                }
-                            }
-                        }
-                    }
-                }
-                _ => {
-                    result += 1.0;
-                }
-            };
-        }
-        CalcResult::Number(result)
-    }
-
-    pub(crate) fn fn_countblank(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        // COUNTBLANK requires only one argument
-        if args.len() != 1 {
-            return CalcResult::new_args_number_error(cell);
-        }
-        let mut result = 0.0;
-        for arg in args {
-            match self.evaluate_node_in_context(arg, cell) {
-                CalcResult::EmptyCell | CalcResult::EmptyArg => result += 1.0,
-                CalcResult::String(s) => {
-                    if s.is_empty() {
-                        result += 1.0
-                    }
-                }
-                CalcResult::Range { left, right } => {
-                    if left.sheet != right.sheet {
-                        return CalcResult::new_error(
-                            Error::VALUE,
-                            cell,
-                            "Ranges are in different sheets".to_string(),
-                        );
-                    }
-                    for row in left.row..(right.row + 1) {
-                        for column in left.column..(right.column + 1) {
-                            match self.evaluate_cell(CellReferenceIndex {
-                                sheet: left.sheet,
-                                row,
-                                column,
-                            }) {
-                                CalcResult::EmptyCell | CalcResult::EmptyArg => result += 1.0,
-                                CalcResult::String(s) => {
-                                    if s.is_empty() {
-                                        result += 1.0
-                                    }
-                                }
-                                _ => {}
-                            }
-                        }
-                    }
-                }
-                _ => {}
-            };
-        }
-        CalcResult::Number(result)
-    }
-
-    pub(crate) fn fn_countif(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        if args.len() == 2 {
-            let arguments = vec![args[0].clone(), args[1].clone()];
-            self.fn_countifs(&arguments, cell)
-        } else {
-            CalcResult::new_args_number_error(cell)
-        }
-    }
-
-    /// AVERAGEIF(criteria_range, criteria, [average_range])
-    /// if average_rage is missing then criteria_range will be used
-    pub(crate) fn fn_averageif(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        if args.len() == 2 {
-            let arguments = vec![args[0].clone(), args[0].clone(), args[1].clone()];
-            self.fn_averageifs(&arguments, cell)
-        } else if args.len() == 3 {
-            let arguments = vec![args[2].clone(), args[0].clone(), args[1].clone()];
-            self.fn_averageifs(&arguments, cell)
-        } else {
-            CalcResult::new_args_number_error(cell)
-        }
-    }
-
-    // FIXME: This function shares a lot of code with apply_ifs. Can we merge them?
-    pub(crate) fn fn_countifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        let args_count = args.len();
-        if args_count < 2 || !args_count.is_multiple_of(2) {
-            return CalcResult::new_args_number_error(cell);
-        }
-
-        let case_count = args_count / 2;
-        // NB: this is a beautiful example of the borrow checker
-        // The order of these two definitions cannot be swapped.
-        let mut criteria = Vec::new();
-        let mut fn_criteria = Vec::new();
-        let ranges = &mut Vec::new();
-        for case_index in 0..case_count {
-            let criterion = self.evaluate_node_in_context(&args[case_index * 2 + 1], cell);
-            criteria.push(criterion);
-            // NB: We cannot do:
-            // fn_criteria.push(build_criteria(&criterion));
-            // because criterion doesn't live long enough
-            let result = self.evaluate_node_in_context(&args[case_index * 2], cell);
-            if result.is_error() {
-                return result;
-            }
-            if let CalcResult::Range { left, right } = result {
-                if left.sheet != right.sheet {
-                    return CalcResult::new_error(
-                        Error::VALUE,
-                        cell,
-                        "Ranges are in different sheets".to_string(),
-                    );
-                }
-                // TODO test ranges are of the same size as sum_range
-                ranges.push(Range { left, right });
-            } else {
-                return CalcResult::new_error(Error::VALUE, cell, "Expected a range".to_string());
-            }
-        }
-        for criterion in criteria.iter() {
-            fn_criteria.push(build_criteria(criterion));
-        }
-
-        let mut total = 0.0;
-        let first_range = &ranges[0];
-        let left_row = first_range.left.row;
-        let left_column = first_range.left.column;
-        let right_row = first_range.right.row;
-        let right_column = first_range.right.column;
-
-        let dimension = match self.workbook.worksheet(first_range.left.sheet) {
-            Ok(s) => s.dimension(),
-            Err(_) => {
-                return CalcResult::new_error(
-                    Error::ERROR,
-                    cell,
-                    format!("Invalid worksheet index: '{}'", first_range.left.sheet),
-                )
-            }
-        };
-        let max_row = dimension.max_row;
-        let max_column = dimension.max_column;
-
-        let open_row = left_row == 1 && right_row == LAST_ROW;
-        let open_column = left_column == 1 && right_column == LAST_COLUMN;
-
-        for row in left_row..right_row + 1 {
-            if open_row && row > max_row {
-                // If the row is larger than the max row in the sheet then all cells are empty.
-                // We compute it only once
-                let mut is_true = true;
-                for fn_criterion in fn_criteria.iter() {
-                    if !fn_criterion(&CalcResult::EmptyCell) {
-                        is_true = false;
-                        break;
-                    }
-                }
-                if is_true {
-                    total += ((LAST_ROW - max_row) * (right_column - left_column + 1)) as f64;
-                }
-                break;
-            }
-            for column in left_column..right_column + 1 {
-                if open_column && column > max_column {
-                    // If the column is larger than the max column in the sheet then all cells are empty.
-                    // We compute it only once
-                    let mut is_true = true;
-                    for fn_criterion in fn_criteria.iter() {
-                        if !fn_criterion(&CalcResult::EmptyCell) {
-                            is_true = false;
-                            break;
-                        }
-                    }
-                    if is_true {
-                        total += (LAST_COLUMN - max_column) as f64;
-                    }
-                    break;
-                }
-                let mut is_true = true;
-                for case_index in 0..case_count {
-                    // We check if value in range n meets criterion n
-                    let range = &ranges[case_index];
-                    let fn_criterion = &fn_criteria[case_index];
-                    let value = self.evaluate_cell(CellReferenceIndex {
-                        sheet: range.left.sheet,
-                        row: range.left.row + row - first_range.left.row,
-                        column: range.left.column + column - first_range.left.column,
-                    });
-                    if !fn_criterion(&value) {
-                        is_true = false;
-                        break;
-                    }
-                }
-                if is_true {
-                    total += 1.0;
-                }
-            }
-        }
-        CalcResult::Number(total)
-    }
-
-    pub(crate) fn apply_ifs<F>(
-        &mut self,
-        args: &[Node],
-        cell: CellReferenceIndex,
-        mut apply: F,
-    ) -> Result<(), CalcResult>
-    where
-        F: FnMut(f64),
-    {
-        let args_count = args.len();
-        if args_count < 3 || args_count.is_multiple_of(2) {
-            return Err(CalcResult::new_args_number_error(cell));
-        }
-        let arg_0 = self.evaluate_node_in_context(&args[0], cell);
-        if arg_0.is_error() {
-            return Err(arg_0);
-        }
-        let sum_range = if let CalcResult::Range { left, right } = arg_0 {
-            if left.sheet != right.sheet {
-                return Err(CalcResult::new_error(
-                    Error::VALUE,
-                    cell,
-                    "Ranges are in different sheets".to_string(),
-                ));
-            }
-            Range { left, right }
-        } else {
-            return Err(CalcResult::new_error(
-                Error::VALUE,
-                cell,
-                "Expected a range".to_string(),
-            ));
-        };
-
-        let case_count = (args_count - 1) / 2;
-        // NB: this is a beautiful example of the borrow checker
-        // The order of these two definitions cannot be swapped.
-        let mut criteria = Vec::new();
-        let mut fn_criteria = Vec::new();
-        let ranges = &mut Vec::new();
-        for case_index in 1..=case_count {
-            let criterion = self.evaluate_node_in_context(&args[case_index * 2], cell);
-            // NB: criterion might be an error. That's ok
-            criteria.push(criterion);
-            // NB: We cannot do:
-            // fn_criteria.push(build_criteria(&criterion));
-            // because criterion doesn't live long enough
-            let result = self.evaluate_node_in_context(&args[case_index * 2 - 1], cell);
-            if result.is_error() {
-                return Err(result);
-            }
-            if let CalcResult::Range { left, right } = result {
-                if left.sheet != right.sheet {
-                    return Err(CalcResult::new_error(
-                        Error::VALUE,
-                        cell,
-                        "Ranges are in different sheets".to_string(),
-                    ));
-                }
-                // TODO test ranges are of the same size as sum_range
-                ranges.push(Range { left, right });
-            } else {
-                return Err(CalcResult::new_error(
-                    Error::VALUE,
-                    cell,
-                    "Expected a range".to_string(),
-                ));
-            }
-        }
-        for criterion in criteria.iter() {
-            fn_criteria.push(build_criteria(criterion));
-        }
-
-        let left_row = sum_range.left.row;
-        let left_column = sum_range.left.column;
-        let mut right_row = sum_range.right.row;
-        let mut right_column = sum_range.right.column;
-
-        if left_row == 1 && right_row == LAST_ROW {
-            right_row = match self.workbook.worksheet(sum_range.left.sheet) {
-                Ok(s) => s.dimension().max_row,
-                Err(_) => {
-                    return Err(CalcResult::new_error(
-                        Error::ERROR,
-                        cell,
-                        format!("Invalid worksheet index: '{}'", sum_range.left.sheet),
-                    ));
-                }
-            };
-        }
-        if left_column == 1 && right_column == LAST_COLUMN {
-            right_column = match self.workbook.worksheet(sum_range.left.sheet) {
-                Ok(s) => s.dimension().max_column,
-                Err(_) => {
-                    return Err(CalcResult::new_error(
-                        Error::ERROR,
-                        cell,
-                        format!("Invalid worksheet index: '{}'", sum_range.left.sheet),
-                    ));
-                }
-            };
-        }
-
-        for row in left_row..right_row + 1 {
-            for column in left_column..right_column + 1 {
-                let mut is_true = true;
-                for case_index in 0..case_count {
-                    // We check if value in range n meets criterion n
-                    let range = &ranges[case_index];
-                    let fn_criterion = &fn_criteria[case_index];
-                    let value = self.evaluate_cell(CellReferenceIndex {
-                        sheet: range.left.sheet,
-                        row: range.left.row + row - sum_range.left.row,
-                        column: range.left.column + column - sum_range.left.column,
-                    });
-                    if !fn_criterion(&value) {
-                        is_true = false;
-                        break;
-                    }
-                }
-                if is_true {
-                    let v = self.evaluate_cell(CellReferenceIndex {
-                        sheet: sum_range.left.sheet,
-                        row,
-                        column,
-                    });
-                    match v {
-                        CalcResult::Number(n) => apply(n),
-                        CalcResult::Error { .. } => return Err(v),
-                        _ => {}
-                    }
-                }
-            }
-        }
-        Ok(())
-    }
-
-    pub(crate) fn fn_averageifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        let mut total = 0.0;
-        let mut count = 0.0;
-
-        let average = |value: f64| {
-            total += value;
-            count += 1.0;
-        };
-        if let Err(e) = self.apply_ifs(args, cell, average) {
-            return e;
-        }
-
-        if count == 0.0 {
-            return CalcResult::Error {
-                error: Error::DIV,
-                origin: cell,
-                message: "division by 0".to_string(),
-            };
-        }
-        CalcResult::Number(total / count)
-    }
-
-    pub(crate) fn fn_minifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        let mut min = f64::INFINITY;
-        let apply_min = |value: f64| min = value.min(min);
-        if let Err(e) = self.apply_ifs(args, cell, apply_min) {
-            return e;
-        }
-
-        if min.is_infinite() {
-            min = 0.0;
-        }
-        CalcResult::Number(min)
-    }
-
-    pub(crate) fn fn_maxifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        let mut max = -f64::INFINITY;
-        let apply_max = |value: f64| max = value.max(max);
-        if let Err(e) = self.apply_ifs(args, cell, apply_max) {
-            return e;
-        }
-        if max.is_infinite() {
-            max = 0.0;
-        }
-        CalcResult::Number(max)
-    }
-
-    pub(crate) fn fn_geomean(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
-        if args.is_empty() {
-            return CalcResult::new_args_number_error(cell);
-        }
-        let mut count = 0.0;
-        let mut product = 1.0;
-        for arg in args {
-            match self.evaluate_node_in_context(arg, cell) {
-                CalcResult::Number(value) => {
-                    count += 1.0;
-                    product *= value;
-                }
-                CalcResult::Boolean(b) => {
-                    if let Node::ReferenceKind { .. } = arg {
-                    } else {
-                        product *= if b { 1.0 } else { 0.0 };
-                        count += 1.0;
-                    }
-                }
-                CalcResult::Range { left, right } => {
-                    if left.sheet != right.sheet {
-                        return CalcResult::new_error(
-                            Error::VALUE,
-                            cell,
-                            "Ranges are in different sheets".to_string(),
-                        );
-                    }
-                    for row in left.row..(right.row + 1) {
-                        for column in left.column..(right.column + 1) {
-                            match self.evaluate_cell(CellReferenceIndex {
-                                sheet: left.sheet,
-                                row,
-                                column,
-                            }) {
-                                CalcResult::Number(value) => {
-                                    count += 1.0;
-                                    product *= value;
-                                }
-                                error @ CalcResult::Error { .. } => return error,
-                                CalcResult::Range { .. } => {
-                                    return CalcResult::new_error(
-                                        Error::ERROR,
-                                        cell,
-                                        "Unexpected Range".to_string(),
-                                    );
-                                }
-                                _ => {}
-                            }
-                        }
-                    }
-                }
-                error @ CalcResult::Error { .. } => return error,
-                CalcResult::String(s) => {
-                    if let Node::ReferenceKind { .. } = arg {
-                        // Do nothing
-                    } else if let Ok(t) = s.parse::<f64>() {
-                        product *= t;
-                        count += 1.0;
-                    } else {
-                        return CalcResult::Error {
-                            error: Error::VALUE,
-                            origin: cell,
-                            message: "Argument cannot be cast into number".to_string(),
-                        };
-                    }
-                }
-                _ => {
-                    // Ignore everything else
-                }
-            };
-        }
-        if count == 0.0 {
-            return CalcResult::Error {
-                error: Error::DIV,
-                origin: cell,
-                message: "Division by Zero".to_string(),
-            };
-        }
-        CalcResult::Number(product.powf(1.0 / count))
-    }
-}

base/src/functions/statistical/beta.rs

@@ -0,0 +1,213 @@
+use statrs::distribution::{Beta, Continuous, ContinuousCDF};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // BETA.DIST(x, alpha, beta, cumulative, [A], [B])
+    pub(crate) fn fn_beta_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let arg_count = args.len();
+        if !(4..=6).contains(&arg_count) {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let alpha = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let beta_param = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // cumulative argument: interpret like Excel
+        let cumulative = match self.evaluate_node_in_context(&args[3], cell) {
+            CalcResult::Boolean(b) => b,
+            CalcResult::Number(n) => n != 0.0,
+            CalcResult::String(s) => {
+                let up = s.to_ascii_uppercase();
+                if up == "TRUE" {
+                    true
+                } else if up == "FALSE" {
+                    false
+                } else {
+                    return CalcResult::Error {
+                        error: Error::VALUE,
+                        origin: cell,
+                        message: "cumulative must be TRUE/FALSE or numeric".to_string(),
+                    };
+                }
+            }
+            error @ CalcResult::Error { .. } => return error,
+            _ => {
+                return CalcResult::Error {
+                    error: Error::VALUE,
+                    origin: cell,
+                    message: "Invalid cumulative argument".to_string(),
+                }
+            }
+        };
+
+        // Optional A, B
+        let a = if arg_count >= 5 {
+            match self.get_number_no_bools(&args[4], cell) {
+                Ok(f) => f,
+                Err(e) => return e,
+            }
+        } else {
+            0.0
+        };
+
+        let b = if arg_count >= 6 {
+            match self.get_number_no_bools(&args[5], cell) {
+                Ok(f) => f,
+                Err(e) => return e,
+            }
+        } else {
+            1.0
+        };
+
+        // Excel: alpha <= 0 or beta <= 0 → #NUM!
+        if alpha <= 0.0 || beta_param <= 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "alpha and beta must be > 0 in BETA.DIST".to_string(),
+            );
+        }
+
+        // Excel: if x < A, x > B, or A = B → #NUM!
+        if b == a || x < a || x > b {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "x must be between A and B and A < B in BETA.DIST".to_string(),
+            );
+        }
+
+        // Transform to standard Beta(0,1)
+        let width = b - a;
+        let t = (x - a) / width;
+
+        let dist = match Beta::new(alpha, beta_param) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Beta distribution".to_string(),
+                )
+            }
+        };
+
+        let result = if cumulative {
+            dist.cdf(t)
+        } else {
+            // general-interval beta pdf: f_X(x) = f_T(t) / (B - A), t=(x-A)/(B-A)
+            dist.pdf(t) / width
+        };
+
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for BETA.DIST".to_string(),
+            );
+        }
+
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_beta_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let arg_count = args.len();
+        if !(3..=5).contains(&arg_count) {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let alpha = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let beta_param = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let a = if arg_count >= 4 {
+            match self.get_number_no_bools(&args[3], cell) {
+                Ok(f) => f,
+                Err(e) => return e,
+            }
+        } else {
+            0.0
+        };
+
+        let b = if arg_count >= 5 {
+            match self.get_number_no_bools(&args[4], cell) {
+                Ok(f) => f,
+                Err(e) => return e,
+            }
+        } else {
+            1.0
+        };
+
+        if alpha <= 0.0 || beta_param <= 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "alpha and beta must be > 0 in BETA.INV".to_string(),
+            );
+        }
+
+        // probability <= 0 or probability > 1 → #NUM!
+        if p <= 0.0 || p > 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "probability must be in (0,1] in BETA.INV".to_string(),
+            );
+        }
+
+        if b <= a {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "A must be < B in BETA.INV".to_string(),
+            );
+        }
+
+        let dist = match Beta::new(alpha, beta_param) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Beta distribution".to_string(),
+                )
+            }
+        };
+
+        let t = dist.inverse_cdf(p);
+        if t.is_nan() || t.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for BETA.INV".to_string(),
+            );
+        }
+
+        // Map back from [0,1] to [A,B]
+        let x = a + t * (b - a);
+        CalcResult::Number(x)
+    }
+}

base/src/functions/statistical/binom.rs

@@ -0,0 +1,311 @@
+use statrs::distribution::{Binomial, Discrete, DiscreteCDF};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_binom_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        // number_s
+        let number_s = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // trials
+        let trials = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // probability_s
+        let p = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // cumulative (logical)
+        let cumulative = match self.get_boolean(&args[3], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        // Domain checks
+        if trials < 0.0
+            || number_s < 0.0
+            || number_s > trials
+            || p.is_nan()
+            || !(0.0..=1.0).contains(&p)
+        {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid parameters for BINOM.DIST".to_string(),
+            );
+        }
+
+        // Limit to u64
+        if trials > u64::MAX as f64 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Number of trials too large".to_string(),
+            );
+        }
+
+        let n = trials as u64;
+        let k = number_s as u64;
+
+        let dist = match Binomial::new(p, n) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for binomial distribution".to_string(),
+                )
+            }
+        };
+
+        let prob = if cumulative { dist.cdf(k) } else { dist.pmf(k) };
+
+        if prob.is_nan() || prob.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for BINOM.DIST".to_string(),
+            );
+        }
+
+        CalcResult::Number(prob)
+    }
+
+    pub(crate) fn fn_binom_dist_range(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() < 3 || args.len() > 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        // trials
+        let trials = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // probability_s
+        let p = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // number_s (lower)
+        let number_s = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // number_s2 (upper, optional)
+        let number_s2 = if args.len() == 4 {
+            match self.get_number_no_bools(&args[3], cell) {
+                Ok(f) => f.trunc(),
+                Err(e) => return e,
+            }
+        } else {
+            number_s
+        };
+
+        if trials < 0.0
+            || number_s < 0.0
+            || number_s2 < 0.0
+            || number_s > number_s2
+            || number_s2 > trials
+            || p.is_nan()
+            || !(0.0..=1.0).contains(&p)
+        {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid parameters for BINOM.DIST.RANGE".to_string(),
+            );
+        }
+
+        if trials > u64::MAX as f64 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Number of trials too large".to_string(),
+            );
+        }
+
+        let n = trials as u64;
+        let lower = number_s as u64;
+        let upper = number_s2 as u64;
+
+        let dist = match Binomial::new(p, n) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for binomial distribution".to_string(),
+                )
+            }
+        };
+
+        let prob = if lower == 0 {
+            dist.cdf(upper)
+        } else {
+            let cdf_upper = dist.cdf(upper);
+            let cdf_below_lower = dist.cdf(lower - 1);
+            cdf_upper - cdf_below_lower
+        };
+
+        if prob.is_nan() || prob.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for BINOM.DIST.RANGE".to_string(),
+            );
+        }
+
+        CalcResult::Number(prob)
+    }
+
+    pub(crate) fn fn_binom_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        // trials
+        let trials = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // probability_s
+        let p = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // alpha
+        let alpha = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        if trials < 0.0
+            || trials > u64::MAX as f64
+            || p.is_nan()
+            || !(0.0..=1.0).contains(&p)
+            || alpha.is_nan()
+            || !(0.0..=1.0).contains(&alpha)
+        {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid parameters for BINOM.INV".to_string(),
+            );
+        }
+
+        let n = trials as u64;
+
+        let dist = match Binomial::new(p, n) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for binomial distribution".to_string(),
+                )
+            }
+        };
+
+        // DiscreteCDF::inverse_cdf returns u64 for binomial
+        let k = statrs::distribution::DiscreteCDF::inverse_cdf(&dist, alpha);
+
+        CalcResult::Number(k as f64)
+    }
+
+    pub(crate) fn fn_negbinom_dist(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        use statrs::distribution::{Discrete, DiscreteCDF, NegativeBinomial};
+
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let number_f = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+        let number_s = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+        let probability_s = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let cumulative = match self.get_boolean(&args[3], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if number_f < 0.0 || number_s < 1.0 || !(0.0..=1.0).contains(&probability_s) {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for NEGBINOM.DIST".to_string(),
+            };
+        }
+
+        // Guard against absurdly large failures that won't fit in u64
+        if number_f > (u64::MAX as f64) {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for NEGBINOM.DIST".to_string(),
+            };
+        }
+
+        let dist = match NegativeBinomial::new(number_s, probability_s) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameter for NEGBINOM.DIST".to_string(),
+                }
+            }
+        };
+
+        let f_u = number_f as u64;
+        let result = if cumulative {
+            dist.cdf(f_u)
+        } else {
+            dist.pmf(f_u)
+        };
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for NEGBINOM.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+}

base/src/functions/statistical/chisq.rs

@@ -0,0 +1,397 @@
+use statrs::distribution::{ChiSquared, Continuous, ContinuousCDF};
+
+use crate::expressions::parser::ArrayNode;
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // CHISQ.DIST(x, deg_freedom, cumulative)
+    pub(crate) fn fn_chisq_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[2], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "x must be >= 0 in CHISQ.DIST".to_string(),
+            );
+        }
+        if df < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in CHISQ.DIST".to_string(),
+            );
+        }
+
+        let dist = match ChiSquared::new(df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Chi-squared distribution".to_string(),
+                )
+            }
+        };
+
+        let result = if cumulative { dist.cdf(x) } else { dist.pdf(x) };
+
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for CHISQ.DIST".to_string(),
+            );
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // CHISQ.DIST.RT(x, deg_freedom)
+    pub(crate) fn fn_chisq_dist_rt(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df_raw = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = df_raw.trunc();
+
+        if x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "x must be >= 0 in CHISQ.DIST.RT".to_string(),
+            );
+        }
+        if df < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in CHISQ.DIST.RT".to_string(),
+            );
+        }
+
+        let dist = match ChiSquared::new(df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Chi-squared distribution".to_string(),
+                )
+            }
+        };
+
+        // Right-tail probability: P(X > x).
+        // Use sf(x) directly for better numerical properties than 1 - cdf(x).
+        let result = dist.sf(x);
+
+        if result.is_nan() || result.is_infinite() || result < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for CHISQ.DIST.RT".to_string(),
+            );
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // CHISQ.INV(probability, deg_freedom)
+    pub(crate) fn fn_chisq_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // if probability < 0 or > 1 → #NUM!
+        if !(0.0..=1.0).contains(&p) {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "probability must be in [0,1] in CHISQ.INV".to_string(),
+            );
+        }
+        if df < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in CHISQ.INV".to_string(),
+            );
+        }
+
+        let dist = match ChiSquared::new(df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Chi-squared distribution".to_string(),
+                )
+            }
+        };
+
+        let x = dist.inverse_cdf(p);
+
+        if x.is_nan() || x.is_infinite() || x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for CHISQ.INV".to_string(),
+            );
+        }
+
+        CalcResult::Number(x)
+    }
+
+    // CHISQ.INV.RT(probability, deg_freedom)
+    pub(crate) fn fn_chisq_inv_rt(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df_raw = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = df_raw.trunc();
+
+        // if probability < 0 or > 1 → #NUM!
+        if !(0.0..=1.0).contains(&p) {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "probability must be in [0,1] in CHISQ.INV.RT".to_string(),
+            );
+        }
+        if df < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in CHISQ.INV.RT".to_string(),
+            );
+        }
+
+        let dist = match ChiSquared::new(df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Chi-squared distribution".to_string(),
+                )
+            }
+        };
+
+        // Right-tail inverse: p = P(X > x) = SF(x) = 1 - CDF(x)
+        // So x = inverse_cdf(1 - p).
+        let x = dist.inverse_cdf(1.0 - p);
+
+        if x.is_nan() || x.is_infinite() || x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for CHISQ.INV.RT".to_string(),
+            );
+        }
+
+        CalcResult::Number(x)
+    }
+
+    pub(crate) fn values_from_range(
+        &mut self,
+        left: CellReferenceIndex,
+        right: CellReferenceIndex,
+    ) -> Result<Vec<Option<f64>>, CalcResult> {
+        let mut values = Vec::new();
+        for row_offset in 0..=(right.row - left.row) {
+            for col_offset in 0..=(right.column - left.column) {
+                let cell_ref = CellReferenceIndex {
+                    sheet: left.sheet,
+                    row: left.row + row_offset,
+                    column: left.column + col_offset,
+                };
+                let cell_value = self.evaluate_cell(cell_ref);
+                match cell_value {
+                    CalcResult::Number(v) => {
+                        values.push(Some(v));
+                    }
+                    error @ CalcResult::Error { .. } => return Err(error),
+                    _ => {
+                        values.push(None);
+                    }
+                }
+            }
+        }
+        Ok(values)
+    }
+
+    pub(crate) fn values_from_array(
+        &mut self,
+        array: Vec<Vec<ArrayNode>>,
+    ) -> Result<Vec<Option<f64>>, Error> {
+        let mut values = Vec::new();
+        for row in array {
+            for item in row {
+                match item {
+                    ArrayNode::Number(f) => {
+                        values.push(Some(f));
+                    }
+                    ArrayNode::Error(error) => {
+                        return Err(error);
+                    }
+                    _ => {
+                        values.push(None);
+                    }
+                }
+            }
+        }
+        Ok(values)
+    }
+
+    // CHISQ.TEST(actual_range, expected_range)
+    pub(crate) fn fn_chisq_test(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (width, height, values_left, values_right) = match self.fn_get_two_matrices(args, cell)
+        {
+            Ok(v) => v,
+            Err(r) => return r,
+        };
+
+        let mut values = Vec::with_capacity(values_left.len());
+
+        // Now we have:
+        // - values: flattened (observed, expected)
+        // - width, height: shape
+        for i in 0..values_left.len() {
+            match (values_left[i], values_right[i]) {
+                (Some(v1), Some(v2)) => {
+                    values.push((v1, v2));
+                }
+                _ => {
+                    values.push((1.0, 1.0));
+                }
+            }
+        }
+        if width == 0 || height == 0 || values.len() < 2 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "CHISQ.TEST requires at least two data points".to_string(),
+            );
+        }
+
+        let mut chi2 = 0.0;
+        for (obs, exp) in &values {
+            if *obs < 0.0 || *exp < 0.0 {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Negative value in CHISQ.TEST data".to_string(),
+                );
+            }
+            if *exp == 0.0 {
+                return CalcResult::new_error(
+                    Error::DIV,
+                    cell,
+                    "Zero expected value in CHISQ.TEST".to_string(),
+                );
+            }
+            let diff = obs - exp;
+            chi2 += (diff * diff) / exp;
+        }
+
+        if chi2 < 0.0 && chi2 > -1e-12 {
+            chi2 = 0.0;
+        }
+
+        let total = width * height;
+        if total <= 1 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "CHISQ.TEST degrees of freedom is zero".to_string(),
+            );
+        }
+
+        let df = if width > 1 && height > 1 {
+            (width - 1) * (height - 1)
+        } else {
+            total - 1
+        };
+
+        let dist = match ChiSquared::new(df as f64) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid degrees of freedom in CHISQ.TEST".to_string(),
+                );
+            }
+        };
+
+        let mut p = 1.0 - dist.cdf(chi2);
+
+        // clamp tiny fp noise
+        if p < 0.0 && p > -1e-15 {
+            p = 0.0;
+        }
+        if p > 1.0 && p < 1.0 + 1e-15 {
+            p = 1.0;
+        }
+
+        CalcResult::Number(p)
+    }
+}

base/src/functions/statistical/correl.rs

@@ -0,0 +1,227 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // CORREL(array1, array2) - Returns the correlation coefficient of two data sets
+    pub(crate) fn fn_correl(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (_, _, values_left, values_right) = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(e) => return e,
+        };
+
+        let mut n = 0.0;
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        let mut sum_x2 = 0.0;
+        let mut sum_y2 = 0.0;
+        let mut sum_xy = 0.0;
+
+        for (x_opt, y_opt) in values_left.into_iter().zip(values_right.into_iter()) {
+            if let (Some(x), Some(y)) = (x_opt, y_opt) {
+                n += 1.0;
+                sum_x += x;
+                sum_y += y;
+                sum_x2 += x * x;
+                sum_y2 += y * y;
+                sum_xy += x * y;
+            }
+        }
+
+        // Need at least 2 valid pairs
+        if n < 2.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "CORREL requires at least two numeric data points in each range".to_string(),
+            );
+        }
+
+        let num = n * sum_xy - sum_x * sum_y;
+        let denom_x = n * sum_x2 - sum_x * sum_x;
+        let denom_y = n * sum_y2 - sum_y * sum_y;
+        let denom = (denom_x * denom_y).sqrt();
+
+        if denom == 0.0 || !denom.is_finite() {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "Division by zero in CORREL".to_string(),
+            );
+        }
+
+        let r = num / denom;
+        CalcResult::Number(r)
+    }
+
+    // SLOPE(known_y's, known_x's) - Returns the slope of the linear regression line
+    pub(crate) fn fn_slope(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (_rows, _cols, values_y, values_x) = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(e) => return e,
+        };
+
+        let mut n = 0.0;
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        let mut sum_x2 = 0.0;
+        let mut sum_xy = 0.0;
+
+        let len = values_y.len().min(values_x.len());
+        for i in 0..len {
+            if let (Some(y), Some(x)) = (values_y[i], values_x[i]) {
+                n += 1.0;
+                sum_x += x;
+                sum_y += y;
+                sum_x2 += x * x;
+                sum_xy += x * y;
+            }
+        }
+
+        if n < 2.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "SLOPE requires at least two numeric data points".to_string(),
+            );
+        }
+
+        let denom = n * sum_x2 - sum_x * sum_x;
+        if denom == 0.0 || !denom.is_finite() {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "Division by zero in SLOPE".to_string(),
+            );
+        }
+
+        let num = n * sum_xy - sum_x * sum_y;
+        let slope = num / denom;
+
+        CalcResult::Number(slope)
+    }
+
+    // INTERCEPT(known_y's, known_x's) - Returns the y-intercept of the linear regression line
+    pub(crate) fn fn_intercept(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (_rows, _cols, values_y, values_x) = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(e) => return e,
+        };
+
+        let mut n = 0.0;
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        let mut sum_x2 = 0.0;
+        let mut sum_xy = 0.0;
+
+        let len = values_y.len().min(values_x.len());
+        for i in 0..len {
+            if let (Some(y), Some(x)) = (values_y[i], values_x[i]) {
+                n += 1.0;
+                sum_x += x;
+                sum_y += y;
+                sum_x2 += x * x;
+                sum_xy += x * y;
+            }
+        }
+
+        if n < 2.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "INTERCEPT requires at least two numeric data points".to_string(),
+            );
+        }
+
+        let denom = n * sum_x2 - sum_x * sum_x;
+        if denom == 0.0 || !denom.is_finite() {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "Division by zero in INTERCEPT".to_string(),
+            );
+        }
+
+        let num = n * sum_xy - sum_x * sum_y;
+        let slope = num / denom;
+        let intercept = (sum_y - slope * sum_x) / n;
+
+        CalcResult::Number(intercept)
+    }
+
+    // STEYX(known_y's, known_x's) - Returns the standard error of the predicted y-values
+    pub(crate) fn fn_steyx(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (_rows, _cols, values_y, values_x) = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(e) => return e,
+        };
+
+        let mut n = 0.0;
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        let mut sum_x2 = 0.0;
+        let mut sum_xy = 0.0;
+
+        // We need the actual pairs again later for residuals
+        let mut pairs: Vec<(f64, f64)> = Vec::new();
+
+        let len = values_y.len().min(values_x.len());
+        for i in 0..len {
+            if let (Some(y), Some(x)) = (values_y[i], values_x[i]) {
+                n += 1.0;
+                sum_x += x;
+                sum_y += y;
+                sum_x2 += x * x;
+                sum_xy += x * y;
+                pairs.push((x, y));
+            }
+        }
+
+        // Need at least 3 points for STEYX (n - 2 in denominator)
+        if n < 3.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "STEYX requires at least three numeric data points".to_string(),
+            );
+        }
+
+        let denom = n * sum_x2 - sum_x * sum_x;
+        if denom == 0.0 || !denom.is_finite() {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "Division by zero in STEYX".to_string(),
+            );
+        }
+
+        let num = n * sum_xy - sum_x * sum_y;
+        let slope = num / denom;
+        let intercept = (sum_y - slope * sum_x) / n;
+
+        // Sum of squared residuals: Σ (y - ŷ)^2, ŷ = intercept + slope * x
+        let mut sse = 0.0;
+        for (x, y) in pairs {
+            let y_hat = intercept + slope * x;
+            let diff = y - y_hat;
+            sse += diff * diff;
+        }
+
+        let dof = n - 2.0;
+        if dof <= 0.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "STEYX has non-positive degrees of freedom".to_string(),
+            );
+        }
+
+        let sey = (sse / dof).sqrt();
+        if !sey.is_finite() {
+            return CalcResult::new_error(Error::DIV, cell, "Numerical error in STEYX".to_string());
+        }
+
+        CalcResult::Number(sey)
+    }
+}

base/src/functions/statistical/covariance.rs

@@ -0,0 +1,264 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_covariance_p(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let values1_opts = match self.evaluate_node_in_context(&args[0], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in first array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "First argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        let values2_opts = match self.evaluate_node_in_context(&args[1], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in second array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Second argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        // Same number of cells
+        if values1_opts.len() != values2_opts.len() {
+            return CalcResult::new_error(
+                Error::NA,
+                cell,
+                "COVARIANCE.P requires arrays of the same size".to_string(),
+            );
+        }
+
+        // Count numeric data points in each array (ignoring text/booleans/empty)
+        let count1 = values1_opts.iter().filter(|v| v.is_some()).count();
+        let count2 = values2_opts.iter().filter(|v| v.is_some()).count();
+
+        if count1 == 0 || count2 == 0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "COVARIANCE.P requires at least one numeric value in each array".to_string(),
+            );
+        }
+
+        if count1 != count2 {
+            return CalcResult::new_error(
+                Error::NA,
+                cell,
+                "COVARIANCE.P arrays must have the same number of numeric data points".to_string(),
+            );
+        }
+
+        // Build paired numeric vectors, position by position
+        let mut xs: Vec<f64> = Vec::with_capacity(count1);
+        let mut ys: Vec<f64> = Vec::with_capacity(count2);
+
+        for (v1_opt, v2_opt) in values1_opts.into_iter().zip(values2_opts.into_iter()) {
+            if let (Some(x), Some(y)) = (v1_opt, v2_opt) {
+                xs.push(x);
+                ys.push(y);
+            }
+        }
+
+        let n = xs.len();
+        if n == 0 {
+            // Should be impossible given the checks above, but guard anyway
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "COVARIANCE.P has no paired numeric data points".to_string(),
+            );
+        }
+
+        let n_f = n as f64;
+
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        for i in 0..n {
+            sum_x += xs[i];
+            sum_y += ys[i];
+        }
+        let mean_x = sum_x / n_f;
+        let mean_y = sum_y / n_f;
+
+        let mut sum_prod = 0.0;
+        for i in 0..n {
+            let dx = xs[i] - mean_x;
+            let dy = ys[i] - mean_y;
+            sum_prod += dx * dy;
+        }
+
+        let cov = sum_prod / n_f;
+        CalcResult::Number(cov)
+    }
+
+    pub(crate) fn fn_covariance_s(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let values1_opts = match self.evaluate_node_in_context(&args[0], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in first array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "First argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        let values2_opts = match self.evaluate_node_in_context(&args[1], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in second array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Second argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        // Same number of cells
+        if values1_opts.len() != values2_opts.len() {
+            return CalcResult::new_error(
+                Error::NA,
+                cell,
+                "COVARIANCE.S requires arrays of the same size".to_string(),
+            );
+        }
+
+        // Count numeric data points in each array (ignoring text/booleans/empty)
+        let count1 = values1_opts.iter().filter(|v| v.is_some()).count();
+        let count2 = values2_opts.iter().filter(|v| v.is_some()).count();
+
+        if count1 == 0 || count2 == 0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "COVARIANCE.S requires numeric values in each array".to_string(),
+            );
+        }
+
+        if count1 != count2 {
+            return CalcResult::new_error(
+                Error::NA,
+                cell,
+                "COVARIANCE.S arrays must have the same number of numeric data points".to_string(),
+            );
+        }
+
+        // Build paired numeric vectors
+        let mut xs: Vec<f64> = Vec::with_capacity(count1);
+        let mut ys: Vec<f64> = Vec::with_capacity(count2);
+
+        for (v1_opt, v2_opt) in values1_opts.into_iter().zip(values2_opts.into_iter()) {
+            if let (Some(x), Some(y)) = (v1_opt, v2_opt) {
+                xs.push(x);
+                ys.push(y);
+            }
+        }
+
+        let n = xs.len();
+        if n < 2 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "COVARIANCE.S requires at least two paired data points".to_string(),
+            );
+        }
+
+        let n_f = n as f64;
+
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        for i in 0..n {
+            sum_x += xs[i];
+            sum_y += ys[i];
+        }
+        let mean_x = sum_x / n_f;
+        let mean_y = sum_y / n_f;
+
+        let mut sum_prod = 0.0;
+        for i in 0..n {
+            let dx = xs[i] - mean_x;
+            let dy = ys[i] - mean_y;
+            sum_prod += dx * dy;
+        }
+
+        let cov = sum_prod / (n_f - 1.0);
+
+        CalcResult::Number(cov)
+    }
+}

base/src/functions/statistical/devsq.rs

@@ -0,0 +1,135 @@
+use crate::constants::{LAST_COLUMN, LAST_ROW};
+use crate::expressions::parser::ArrayNode;
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // DEVSQ(number1, [number2], ...)
+    pub(crate) fn fn_devsq(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        // tiny helper so we don't repeat ourselves
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // We ignore booleans and strings
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // We ignore booleans and strings
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // We ignore booleans and strings
+                }
+            };
+        }
+
+        if count == 0 {
+            // No numeric data at all
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "DEVSQ with no numeric data".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut result = sumsq - (sum * sum) / n;
+
+        // Numerical noise can make result slightly negative when it should be 0
+        if result < 0.0 && result > -1e-12 {
+            result = 0.0;
+        }
+
+        CalcResult::Number(result)
+    }
+}

base/src/functions/statistical/exponential.rs

@@ -0,0 +1,54 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_expon_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        // EXPON.DIST(x, lambda, cumulative)
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let lambda = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[2], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if x < 0.0 || lambda <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for EXPON.DIST".to_string(),
+            };
+        }
+
+        let result = if cumulative {
+            // CDF
+            1.0 - (-lambda * x).exp()
+        } else {
+            // PDF
+            lambda * (-lambda * x).exp()
+        };
+
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for EXPON.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+}

base/src/functions/statistical/fisher.rs

@@ -0,0 +1,418 @@
+use statrs::distribution::{Continuous, ContinuousCDF, FisherSnedecor};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::functions::statistical::t_dist::sample_var;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // FISHER(x) = 0.5 * ln((1 + x) / (1 - x))
+    pub(crate) fn fn_fisher(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        if x <= -1.0 || x >= 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "x must be between -1 and 1 (exclusive) in FISHER".to_string(),
+            };
+        }
+
+        let ratio = (1.0 + x) / (1.0 - x);
+        let result = 0.5 * ratio.ln();
+
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for FISHER".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // FISHERINV(y) = (e^(2y) - 1) / (e^(2y) + 1) = tanh(y)
+    pub(crate) fn fn_fisher_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let y = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // Use tanh directly to avoid overflow from exp(2y)
+        let result = y.tanh();
+
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for FISHERINV".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // F.DIST(x, deg_freedom1, deg_freedom2, cumulative)
+    pub(crate) fn fn_f_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df1 = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+        let df2 = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[3], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        // Excel domain checks
+        if x < 0.0 {
+            return CalcResult::new_error(Error::NUM, cell, "x must be >= 0 in F.DIST".to_string());
+        }
+        if df1 < 1.0 || df2 < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in F.DIST".to_string(),
+            );
+        }
+
+        let dist = match FisherSnedecor::new(df1, df2) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for F distribution".to_string(),
+                )
+            }
+        };
+
+        let result = if cumulative { dist.cdf(x) } else { dist.pdf(x) };
+
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for F.DIST".to_string(),
+            );
+        }
+
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_f_dist_rt(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        // F.DIST.RT(x, deg_freedom1, deg_freedom2)
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df1 = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+        let df2 = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        if x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "x must be >= 0 in F.DIST.RT".to_string(),
+            );
+        }
+        if df1 < 1.0 || df2 < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in F.DIST.RT".to_string(),
+            );
+        }
+
+        let dist = match FisherSnedecor::new(df1, df2) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for F distribution".to_string(),
+                )
+            }
+        };
+
+        // Right-tail probability: P(F > x) = 1 - CDF(x)
+        let result = 1.0 - dist.cdf(x);
+
+        if result.is_nan() || result.is_infinite() || result < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for F.DIST.RT".to_string(),
+            );
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // F.INV(probability, deg_freedom1, deg_freedom2)
+    pub(crate) fn fn_f_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let df1 = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+        let df2 = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // probability < 0 or > 1 → #NUM!
+        if !(0.0..=1.0).contains(&p) {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "probability must be in [0,1] in F.INV".to_string(),
+            );
+        }
+        if df1 < 1.0 || df2 < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in F.INV".to_string(),
+            );
+        }
+
+        let dist = match FisherSnedecor::new(df1, df2) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for F distribution".to_string(),
+                )
+            }
+        };
+
+        let x = dist.inverse_cdf(p);
+        if x.is_nan() || x.is_infinite() || x < 0.0 {
+            return CalcResult::new_error(Error::NUM, cell, "Invalid result for F.INV".to_string());
+        }
+
+        CalcResult::Number(x)
+    }
+
+    // F.INV.RT(probability, deg_freedom1, deg_freedom2)
+    pub(crate) fn fn_f_inv_rt(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let df1 = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+        let df2 = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        if p <= 0.0 || p > 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "probability must be in (0,1] in F.INV.RT".to_string(),
+            );
+        }
+        if df1 < 1.0 || df2 < 1.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "degrees of freedom must be >= 1 in F.INV.RT".to_string(),
+            );
+        }
+
+        let dist = match FisherSnedecor::new(df1, df2) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for F distribution".to_string(),
+                )
+            }
+        };
+
+        // p is right-tail: p = P(F > x) = 1 - CDF(x)
+        let x = dist.inverse_cdf(1.0 - p);
+        if x.is_nan() || x.is_infinite() || x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for F.INV.RT".to_string(),
+            );
+        }
+
+        CalcResult::Number(x)
+    }
+
+    // F.TEST(array1, array2)
+    pub(crate) fn fn_f_test(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let values1_opts = match self.evaluate_node_in_context(&args[0], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in first array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "First argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        // Get second sample as Vec<Option<f64>>
+        let values2_opts = match self.evaluate_node_in_context(&args[1], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in second array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Second argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        let values1: Vec<f64> = values1_opts.into_iter().flatten().collect();
+        let values2: Vec<f64> = values2_opts.into_iter().flatten().collect();
+
+        let n1 = values1.len();
+        let n2 = values2.len();
+
+        // If fewer than 2 numeric values in either sample -> #DIV/0!
+        if n1 < 2 || n2 < 2 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "F.TEST requires at least two numeric values in each sample".to_string(),
+            );
+        }
+
+        let v1 = sample_var(&values1);
+        let v2 = sample_var(&values2);
+
+        if v1 <= 0.0 || v2 <= 0.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "Variance of one sample is zero in F.TEST".to_string(),
+            );
+        }
+
+        // F ratio: larger variance / smaller variance
+        let mut f = v1 / v2;
+        let mut df1 = (n1 - 1) as f64;
+        let mut df2 = (n2 - 1) as f64;
+
+        if f < 1.0 {
+            f = 1.0 / f;
+            std::mem::swap(&mut df1, &mut df2);
+        }
+
+        let dist = match FisherSnedecor::new(df1, df2) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for F distribution in F.TEST".to_string(),
+                );
+            }
+        };
+
+        // One-tailed right-tail probability
+        let tail = 1.0 - dist.cdf(f);
+        // F.TEST is two-tailed: p = 2 * tail (with F >= 1)
+        let mut p = 2.0 * tail;
+
+        // Clamp tiny FP noise
+        if p < 0.0 && p > -1e-15 {
+            p = 0.0;
+        }
+        if p > 1.0 && p < 1.0 + 1e-15 {
+            p = 1.0;
+        }
+
+        CalcResult::Number(p)
+    }
+}

base/src/functions/statistical/gamma.rs

@@ -0,0 +1,194 @@
+use statrs::distribution::{Continuous, ContinuousCDF, Gamma};
+use statrs::function::gamma::{gamma, ln_gamma};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_gamma(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        if x < 0.0 && x.floor() == x {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for Gamma function".to_string(),
+            };
+        }
+        let result = gamma(x);
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for Gamma function".to_string(),
+            };
+        }
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_gamma_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        // GAMMA.DIST(x, alpha, beta, cumulative)
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let alpha = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let beta_scale = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[3], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "x must be >= 0 in GAMMA.DIST".to_string(),
+            );
+        }
+        if alpha <= 0.0 || beta_scale <= 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "alpha and beta must be > 0 in GAMMA.DIST".to_string(),
+            );
+        }
+
+        let rate = 1.0 / beta_scale;
+
+        let dist = match Gamma::new(alpha, rate) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Gamma distribution".to_string(),
+                )
+            }
+        };
+
+        let result = if cumulative { dist.cdf(x) } else { dist.pdf(x) };
+
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for GAMMA.DIST".to_string(),
+            );
+        }
+
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_gamma_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        // GAMMA.INV(probability, alpha, beta)
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let alpha = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let beta_scale = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        if !(0.0..=1.0).contains(&p) {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "probability must be in [0,1] in GAMMA.INV".to_string(),
+            );
+        }
+
+        if alpha <= 0.0 || beta_scale <= 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "alpha and beta must be > 0 in GAMMA.INV".to_string(),
+            );
+        }
+
+        let rate = 1.0 / beta_scale;
+
+        let dist = match Gamma::new(alpha, rate) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Gamma distribution".to_string(),
+                )
+            }
+        };
+
+        let x = dist.inverse_cdf(p);
+        if x.is_nan() || x.is_infinite() || x < 0.0 {
+            return CalcResult::new_error(
+                Error::NUM,
+                cell,
+                "Invalid result for GAMMA.INV".to_string(),
+            );
+        }
+
+        CalcResult::Number(x)
+    }
+
+    pub(crate) fn fn_gamma_ln(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        if x < 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for Gamma function".to_string(),
+            };
+        }
+        let result = ln_gamma(x);
+        if result.is_nan() || result.is_infinite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for Gamma Ln function".to_string(),
+            };
+        }
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_gamma_ln_precise(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        self.fn_gamma_ln(args, cell)
+    }
+}

base/src/functions/statistical/gauss.rs

@@ -0,0 +1,39 @@
+use statrs::distribution::{ContinuousCDF, Normal};
+
+use crate::expressions::token::Error;
+use crate::expressions::types::CellReferenceIndex;
+use crate::{calc_result::CalcResult, expressions::parser::Node, model::Model};
+
+impl Model {
+    pub(crate) fn fn_gauss(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let z = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(s) => return s,
+        };
+        let dist = match Normal::new(0.0, 1.0) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::ERROR,
+                    origin: cell,
+                    message: "Failed to construct standard normal distribution".to_string(),
+                }
+            }
+        };
+
+        let result = dist.cdf(z) - 0.5;
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for GAUSS".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+}

base/src/functions/statistical/geomean.rs

@@ -0,0 +1,87 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_geomean(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+        let mut count = 0.0;
+        let mut product = 1.0;
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    count += 1.0;
+                    product *= value;
+                }
+                CalcResult::Boolean(b) => {
+                    if let Node::ReferenceKind { .. } = arg {
+                    } else {
+                        product *= if b { 1.0 } else { 0.0 };
+                        count += 1.0;
+                    }
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+                    for row in left.row..(right.row + 1) {
+                        for column in left.column..(right.column + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    count += 1.0;
+                                    product *= value;
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                CalcResult::Range { .. } => {
+                                    return CalcResult::new_error(
+                                        Error::ERROR,
+                                        cell,
+                                        "Unexpected Range".to_string(),
+                                    );
+                                }
+                                _ => {}
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                CalcResult::String(s) => {
+                    if let Node::ReferenceKind { .. } = arg {
+                        // Do nothing
+                    } else if let Ok(t) = s.parse::<f64>() {
+                        product *= t;
+                        count += 1.0;
+                    } else {
+                        return CalcResult::Error {
+                            error: Error::VALUE,
+                            origin: cell,
+                            message: "Argument cannot be cast into number".to_string(),
+                        };
+                    }
+                }
+                _ => {
+                    // Ignore everything else
+                }
+            };
+        }
+        if count == 0.0 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "Division by Zero".to_string(),
+            };
+        }
+        CalcResult::Number(product.powf(1.0 / count))
+    }
+}

base/src/functions/statistical/hypegeom.rs

@@ -0,0 +1,108 @@
+use statrs::distribution::{Discrete, DiscreteCDF, Hypergeometric};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // =HYPGEOM.DIST(sample_s, number_sample, population_s, number_pop, cumulative)
+    pub(crate) fn fn_hyp_geom_dist(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 5 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        // sample_s (number of successes in the sample)
+        let sample_s = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // number_sample (sample size)
+        let number_sample = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // population_s (number of successes in the population)
+        let population_s = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // number_pop (population size)
+        let number_pop = match self.get_number_no_bools(&args[3], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[4], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if sample_s < 0.0 || sample_s > f64::min(number_sample, population_s) {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for HYPGEOM.DIST".to_string(),
+            };
+        }
+
+        if sample_s < f64::max(0.0, number_sample + population_s - number_pop) {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for HYPGEOM.DIST".to_string(),
+            };
+        }
+
+        if number_sample <= 0.0 || number_sample > number_pop {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for HYPGEOM.DIST".to_string(),
+            };
+        }
+
+        if population_s <= 0.0 || population_s > number_pop {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for HYPGEOM.DIST".to_string(),
+            };
+        }
+
+        let n_pop = number_pop as u64;
+        let k_pop = population_s as u64;
+        let n_sample = number_sample as u64;
+        let k = sample_s as u64;
+
+        let dist = match Hypergeometric::new(n_pop, k_pop, n_sample) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for hypergeometric distribution".to_string(),
+                )
+            }
+        };
+
+        let prob = if cumulative { dist.cdf(k) } else { dist.pmf(k) };
+
+        if !prob.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for HYPGEOM.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(prob)
+    }
+}

base/src/functions/statistical/if_ifs.rs

@@ -0,0 +1,337 @@
+use crate::constants::{LAST_COLUMN, LAST_ROW};
+use crate::expressions::types::CellReferenceIndex;
+use crate::functions::util::build_criteria;
+use crate::{
+    calc_result::{CalcResult, Range},
+    expressions::parser::Node,
+    expressions::token::Error,
+    model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_countif(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() == 2 {
+            let arguments = vec![args[0].clone(), args[1].clone()];
+            self.fn_countifs(&arguments, cell)
+        } else {
+            CalcResult::new_args_number_error(cell)
+        }
+    }
+
+    /// AVERAGEIF(criteria_range, criteria, [average_range])
+    /// if average_rage is missing then criteria_range will be used
+    pub(crate) fn fn_averageif(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() == 2 {
+            let arguments = vec![args[0].clone(), args[0].clone(), args[1].clone()];
+            self.fn_averageifs(&arguments, cell)
+        } else if args.len() == 3 {
+            let arguments = vec![args[2].clone(), args[0].clone(), args[1].clone()];
+            self.fn_averageifs(&arguments, cell)
+        } else {
+            CalcResult::new_args_number_error(cell)
+        }
+    }
+
+    // FIXME: This function shares a lot of code with apply_ifs. Can we merge them?
+    pub(crate) fn fn_countifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let args_count = args.len();
+        if args_count < 2 || !args_count.is_multiple_of(2) {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let case_count = args_count / 2;
+        // NB: this is a beautiful example of the borrow checker
+        // The order of these two definitions cannot be swapped.
+        let mut criteria = Vec::new();
+        let mut fn_criteria = Vec::new();
+        let ranges = &mut Vec::new();
+        for case_index in 0..case_count {
+            let criterion = self.evaluate_node_in_context(&args[case_index * 2 + 1], cell);
+            criteria.push(criterion);
+            // NB: We cannot do:
+            // fn_criteria.push(build_criteria(&criterion));
+            // because criterion doesn't live long enough
+            let result = self.evaluate_node_in_context(&args[case_index * 2], cell);
+            if result.is_error() {
+                return result;
+            }
+            if let CalcResult::Range { left, right } = result {
+                if left.sheet != right.sheet {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Ranges are in different sheets".to_string(),
+                    );
+                }
+                // TODO test ranges are of the same size as sum_range
+                ranges.push(Range { left, right });
+            } else {
+                return CalcResult::new_error(Error::VALUE, cell, "Expected a range".to_string());
+            }
+        }
+        for criterion in criteria.iter() {
+            fn_criteria.push(build_criteria(criterion));
+        }
+
+        let mut total = 0.0;
+        let first_range = &ranges[0];
+        let left_row = first_range.left.row;
+        let left_column = first_range.left.column;
+        let right_row = first_range.right.row;
+        let right_column = first_range.right.column;
+
+        let dimension = match self.workbook.worksheet(first_range.left.sheet) {
+            Ok(s) => s.dimension(),
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::ERROR,
+                    cell,
+                    format!("Invalid worksheet index: '{}'", first_range.left.sheet),
+                )
+            }
+        };
+        let max_row = dimension.max_row;
+        let max_column = dimension.max_column;
+
+        let open_row = left_row == 1 && right_row == LAST_ROW;
+        let open_column = left_column == 1 && right_column == LAST_COLUMN;
+
+        for row in left_row..right_row + 1 {
+            if open_row && row > max_row {
+                // If the row is larger than the max row in the sheet then all cells are empty.
+                // We compute it only once
+                let mut is_true = true;
+                for fn_criterion in fn_criteria.iter() {
+                    if !fn_criterion(&CalcResult::EmptyCell) {
+                        is_true = false;
+                        break;
+                    }
+                }
+                if is_true {
+                    total += ((LAST_ROW - max_row) * (right_column - left_column + 1)) as f64;
+                }
+                break;
+            }
+            for column in left_column..right_column + 1 {
+                if open_column && column > max_column {
+                    // If the column is larger than the max column in the sheet then all cells are empty.
+                    // We compute it only once
+                    let mut is_true = true;
+                    for fn_criterion in fn_criteria.iter() {
+                        if !fn_criterion(&CalcResult::EmptyCell) {
+                            is_true = false;
+                            break;
+                        }
+                    }
+                    if is_true {
+                        total += (LAST_COLUMN - max_column) as f64;
+                    }
+                    break;
+                }
+                let mut is_true = true;
+                for case_index in 0..case_count {
+                    // We check if value in range n meets criterion n
+                    let range = &ranges[case_index];
+                    let fn_criterion = &fn_criteria[case_index];
+                    let value = self.evaluate_cell(CellReferenceIndex {
+                        sheet: range.left.sheet,
+                        row: range.left.row + row - first_range.left.row,
+                        column: range.left.column + column - first_range.left.column,
+                    });
+                    if !fn_criterion(&value) {
+                        is_true = false;
+                        break;
+                    }
+                }
+                if is_true {
+                    total += 1.0;
+                }
+            }
+        }
+        CalcResult::Number(total)
+    }
+
+    pub(crate) fn apply_ifs<F>(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+        mut apply: F,
+    ) -> Result<(), CalcResult>
+    where
+        F: FnMut(f64),
+    {
+        let args_count = args.len();
+        if args_count < 3 || args_count.is_multiple_of(2) {
+            return Err(CalcResult::new_args_number_error(cell));
+        }
+        let arg_0 = self.evaluate_node_in_context(&args[0], cell);
+        if arg_0.is_error() {
+            return Err(arg_0);
+        }
+        let sum_range = if let CalcResult::Range { left, right } = arg_0 {
+            if left.sheet != right.sheet {
+                return Err(CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Ranges are in different sheets".to_string(),
+                ));
+            }
+            Range { left, right }
+        } else {
+            return Err(CalcResult::new_error(
+                Error::VALUE,
+                cell,
+                "Expected a range".to_string(),
+            ));
+        };
+
+        let case_count = (args_count - 1) / 2;
+        // NB: this is a beautiful example of the borrow checker
+        // The order of these two definitions cannot be swapped.
+        let mut criteria = Vec::new();
+        let mut fn_criteria = Vec::new();
+        let ranges = &mut Vec::new();
+        for case_index in 1..=case_count {
+            let criterion = self.evaluate_node_in_context(&args[case_index * 2], cell);
+            // NB: criterion might be an error. That's ok
+            criteria.push(criterion);
+            // NB: We cannot do:
+            // fn_criteria.push(build_criteria(&criterion));
+            // because criterion doesn't live long enough
+            let result = self.evaluate_node_in_context(&args[case_index * 2 - 1], cell);
+            if result.is_error() {
+                return Err(result);
+            }
+            if let CalcResult::Range { left, right } = result {
+                if left.sheet != right.sheet {
+                    return Err(CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Ranges are in different sheets".to_string(),
+                    ));
+                }
+                // TODO test ranges are of the same size as sum_range
+                ranges.push(Range { left, right });
+            } else {
+                return Err(CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Expected a range".to_string(),
+                ));
+            }
+        }
+        for criterion in criteria.iter() {
+            fn_criteria.push(build_criteria(criterion));
+        }
+
+        let left_row = sum_range.left.row;
+        let left_column = sum_range.left.column;
+        let mut right_row = sum_range.right.row;
+        let mut right_column = sum_range.right.column;
+
+        if left_row == 1 && right_row == LAST_ROW {
+            right_row = match self.workbook.worksheet(sum_range.left.sheet) {
+                Ok(s) => s.dimension().max_row,
+                Err(_) => {
+                    return Err(CalcResult::new_error(
+                        Error::ERROR,
+                        cell,
+                        format!("Invalid worksheet index: '{}'", sum_range.left.sheet),
+                    ));
+                }
+            };
+        }
+        if left_column == 1 && right_column == LAST_COLUMN {
+            right_column = match self.workbook.worksheet(sum_range.left.sheet) {
+                Ok(s) => s.dimension().max_column,
+                Err(_) => {
+                    return Err(CalcResult::new_error(
+                        Error::ERROR,
+                        cell,
+                        format!("Invalid worksheet index: '{}'", sum_range.left.sheet),
+                    ));
+                }
+            };
+        }
+
+        for row in left_row..right_row + 1 {
+            for column in left_column..right_column + 1 {
+                let mut is_true = true;
+                for case_index in 0..case_count {
+                    // We check if value in range n meets criterion n
+                    let range = &ranges[case_index];
+                    let fn_criterion = &fn_criteria[case_index];
+                    let value = self.evaluate_cell(CellReferenceIndex {
+                        sheet: range.left.sheet,
+                        row: range.left.row + row - sum_range.left.row,
+                        column: range.left.column + column - sum_range.left.column,
+                    });
+                    if !fn_criterion(&value) {
+                        is_true = false;
+                        break;
+                    }
+                }
+                if is_true {
+                    let v = self.evaluate_cell(CellReferenceIndex {
+                        sheet: sum_range.left.sheet,
+                        row,
+                        column,
+                    });
+                    match v {
+                        CalcResult::Number(n) => apply(n),
+                        CalcResult::Error { .. } => return Err(v),
+                        _ => {}
+                    }
+                }
+            }
+        }
+        Ok(())
+    }
+
+    pub(crate) fn fn_averageifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let mut total = 0.0;
+        let mut count = 0.0;
+
+        let average = |value: f64| {
+            total += value;
+            count += 1.0;
+        };
+        if let Err(e) = self.apply_ifs(args, cell, average) {
+            return e;
+        }
+
+        if count == 0.0 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "division by 0".to_string(),
+            };
+        }
+        CalcResult::Number(total / count)
+    }
+
+    pub(crate) fn fn_minifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let mut min = f64::INFINITY;
+        let apply_min = |value: f64| min = value.min(min);
+        if let Err(e) = self.apply_ifs(args, cell, apply_min) {
+            return e;
+        }
+
+        if min.is_infinite() {
+            min = 0.0;
+        }
+        CalcResult::Number(min)
+    }
+
+    pub(crate) fn fn_maxifs(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let mut max = -f64::INFINITY;
+        let apply_max = |value: f64| max = value.max(max);
+        if let Err(e) = self.apply_ifs(args, cell, apply_max) {
+            return e;
+        }
+        if max.is_infinite() {
+            max = 0.0;
+        }
+        CalcResult::Number(max)
+    }
+}

base/src/functions/statistical/log_normal.rs

@@ -0,0 +1,124 @@
+use statrs::distribution::{Continuous, ContinuousCDF, LogNormal};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_log_norm_dist(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let mean = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let std_dev = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let cumulative = match self.get_boolean(&args[3], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        // Excel domain checks
+        if x <= 0.0 || std_dev <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for LOGNORM.DIST".to_string(),
+            };
+        }
+
+        let dist = match LogNormal::new(mean, std_dev) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameter for LOGNORM.DIST".to_string(),
+                }
+            }
+        };
+
+        let result = if cumulative { dist.cdf(x) } else { dist.pdf(x) };
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for LOGNORM.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    pub(crate) fn fn_log_norm_inv(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        use statrs::distribution::{ContinuousCDF, LogNormal};
+
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let mean = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let std_dev = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // Excel domain checks
+        if p <= 0.0 || p >= 1.0 || std_dev <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for LOGNORM.INV".to_string(),
+            };
+        }
+
+        let dist = match LogNormal::new(mean, std_dev) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameter for LOGNORM.INV".to_string(),
+                }
+            }
+        };
+
+        let result = dist.inverse_cdf(p);
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameter for LOGNORM.INV".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+}

base/src/functions/statistical/mod.rs

@@ -0,0 +1,26 @@
+mod beta;
+mod binom;
+mod chisq;
+mod correl;
+mod count_and_average;
+mod covariance;
+mod devsq;
+mod exponential;
+mod fisher;
+mod gamma;
+mod gauss;
+mod geomean;
+mod hypegeom;
+mod if_ifs;
+mod log_normal;
+mod normal;
+mod pearson;
+mod phi;
+mod poisson;
+mod rank_eq_avg;
+mod standard_dev;
+mod standardize;
+mod t_dist;
+mod variance;
+mod weibull;
+mod z_test;

base/src/functions/statistical/normal.rs

@@ -0,0 +1,325 @@
+use statrs::distribution::{Continuous, ContinuousCDF, Normal, StudentsT};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // NORM.DIST(x, mean, standard_dev, cumulative)
+    pub(crate) fn fn_norm_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let mean = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let std_dev = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let cumulative = match self.get_boolean(&args[3], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        // Excel: standard_dev must be > 0
+        if std_dev <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "standard_dev must be > 0 in NORM.DIST".to_string(),
+            };
+        }
+
+        let dist = match Normal::new(mean, std_dev) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for NORM.DIST".to_string(),
+                }
+            }
+        };
+
+        let result = if cumulative { dist.cdf(x) } else { dist.pdf(x) };
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for NORM.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // NORM.INV(probability, mean, standard_dev)
+    pub(crate) fn fn_norm_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let mean = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let std_dev = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        if p <= 0.0 || p >= 1.0 || std_dev <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for NORM.INV".to_string(),
+            };
+        }
+
+        let dist = match Normal::new(mean, std_dev) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for NORM.INV".to_string(),
+                }
+            }
+        };
+
+        let x = dist.inverse_cdf(p);
+
+        if !x.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for NORM.INV".to_string(),
+            };
+        }
+
+        CalcResult::Number(x)
+    }
+
+    // NORM.S.DIST(z, cumulative)
+    pub(crate) fn fn_norm_s_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let z = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let cumulative = match self.get_boolean(&args[1], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        let dist = match Normal::new(0.0, 1.0) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::ERROR,
+                    origin: cell,
+                    message: "Failed to construct standard normal distribution".to_string(),
+                }
+            }
+        };
+
+        let result = if cumulative { dist.cdf(z) } else { dist.pdf(z) };
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for NORM.S.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // NORM.S.INV(probability)
+    pub(crate) fn fn_norm_s_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        if p <= 0.0 || p >= 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "probability must be in (0,1) in NORM.S.INV".to_string(),
+            };
+        }
+
+        let dist = match Normal::new(0.0, 1.0) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::ERROR,
+                    origin: cell,
+                    message: "Failed to construct standard normal distribution".to_string(),
+                }
+            }
+        };
+
+        let z = dist.inverse_cdf(p);
+
+        if !z.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for NORM.S.INV".to_string(),
+            };
+        }
+
+        CalcResult::Number(z)
+    }
+
+    pub(crate) fn fn_confidence_norm(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let alpha = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let std_dev = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let size = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.floor(),
+            Err(e) => return e,
+        };
+
+        if alpha <= 0.0 || alpha >= 1.0 || std_dev <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for CONFIDENCE.NORM".to_string(),
+            };
+        }
+        if size < 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Sample size must be at least 1".to_string(),
+            };
+        }
+
+        let normal = match Normal::new(0.0, 1.0) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::ERROR,
+                    cell,
+                    "Failed to construct normal distribution".to_string(),
+                )
+            }
+        };
+
+        let quantile = normal.inverse_cdf(1.0 - alpha / 2.0);
+        if !quantile.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid quantile for CONFIDENCE.NORM".to_string(),
+            };
+        }
+
+        let margin = quantile * std_dev / size.sqrt();
+        CalcResult::Number(margin)
+    }
+
+    pub(crate) fn fn_confidence_t(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let alpha = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let std_dev = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let size = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // Domain checks
+        if alpha <= 0.0 || alpha >= 1.0 || std_dev <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for CONFIDENCE.T".to_string(),
+            };
+        }
+
+        // Need at least 2 observations so df = n - 1 > 0
+        if size < 2.0 {
+            return CalcResult::Error {
+                error: Error::DIV,
+                origin: cell,
+                message: "Sample size must be at least 2".to_string(),
+            };
+        }
+
+        let df = size - 1.0;
+
+        let t_dist = match StudentsT::new(0.0, 1.0, df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::ERROR,
+                    cell,
+                    "Failed to construct Student's t distribution".to_string(),
+                )
+            }
+        };
+
+        // Two-sided CI => use 1 - alpha/2
+        let t_crit = t_dist.inverse_cdf(1.0 - alpha / 2.0);
+        if !t_crit.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid quantile for CONFIDENCE.T".to_string(),
+            };
+        }
+
+        let margin = t_crit * std_dev / size.sqrt();
+        CalcResult::Number(margin)
+    }
+}

base/src/functions/statistical/pearson.rs

@@ -0,0 +1,113 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // PEARSON(array1, array2)
+    pub(crate) fn fn_pearson(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (_, _, values_left, values_right) = match self.fn_get_two_matrices(args, cell) {
+            Ok(result) => result,
+            Err(e) => return e,
+        };
+
+        // Flatten into (x, y) pairs, skipping non-numeric entries (None)
+        let mut n: f64 = 0.0;
+        let mut sum_x = 0.0;
+        let mut sum_y = 0.0;
+        let mut sum_x2 = 0.0;
+        let mut sum_y2 = 0.0;
+        let mut sum_xy = 0.0;
+
+        let len = values_left.len().min(values_right.len());
+        for i in 0..len {
+            match (values_left[i], values_right[i]) {
+                (Some(x), Some(y)) => {
+                    n += 1.0;
+                    sum_x += x;
+                    sum_y += y;
+                    sum_x2 += x * x;
+                    sum_y2 += y * y;
+                    sum_xy += x * y;
+                }
+                _ => {
+                    // Ignore pairs where at least one side is non-numeric
+                }
+            }
+        }
+
+        if n < 2.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "PEARSON requires at least two numeric pairs".to_string(),
+            );
+        }
+
+        // Pearson correlation:
+        // r = [ n*Σxy - (Σx)(Σy) ] / sqrt( [n*Σx² - (Σx)²] [n*Σy² - (Σy)²] )
+        let num = n * sum_xy - sum_x * sum_y;
+        let denom_x = n * sum_x2 - sum_x * sum_x;
+        let denom_y = n * sum_y2 - sum_y * sum_y;
+
+        if denom_x.abs() < 1e-15 || denom_y.abs() < 1e-15 {
+            // Zero variance in at least one series
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "PEARSON cannot be computed when one series has zero variance".to_string(),
+            );
+        }
+
+        let denom = (denom_x * denom_y).sqrt();
+
+        CalcResult::Number(num / denom)
+    }
+
+    // RSQ(array1, array2) = CORREL(array1, array2)^2
+    pub(crate) fn fn_rsq(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        let (_rows, _cols, values1, values2) = match self.fn_get_two_matrices(args, cell) {
+            Ok(s) => s,
+            Err(e) => return e,
+        };
+
+        let mut n = 0.0_f64;
+        let mut sum_x = 0.0_f64;
+        let mut sum_y = 0.0_f64;
+        let mut sum_x2 = 0.0_f64;
+        let mut sum_y2 = 0.0_f64;
+        let mut sum_xy = 0.0_f64;
+
+        let len = values1.len().min(values2.len());
+        for i in 0..len {
+            if let (Some(x), Some(y)) = (values1[i], values2[i]) {
+                n += 1.0;
+                sum_x += x;
+                sum_y += y;
+                sum_x2 += x * x;
+                sum_y2 += y * y;
+                sum_xy += x * y;
+            }
+        }
+
+        if n < 2.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "RSQ requires at least two numeric data points in each range".to_string(),
+            );
+        }
+
+        let num = n * sum_xy - sum_x * sum_y;
+        let denom_x = n * sum_x2 - sum_x * sum_x;
+        let denom_y = n * sum_y2 - sum_y * sum_y;
+        let denom = (denom_x * denom_y).sqrt();
+
+        if denom == 0.0 || !denom.is_finite() {
+            return CalcResult::new_error(Error::DIV, cell, "Division by zero in RSQ".to_string());
+        }
+
+        let r = num / denom;
+        CalcResult::Number(r * r)
+    }
+}

base/src/functions/statistical/phi.rs

@@ -0,0 +1,21 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{calc_result::CalcResult, expressions::parser::Node, model::Model};
+
+impl Model {
+    // PHI(x) = standard normal PDF at x
+    pub(crate) fn fn_phi(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 1 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // Standard normal PDF: (1 / sqrt(2π)) * exp(-x^2 / 2)
+        let result = (-(x * x) / 2.0).exp() / (2.0 * std::f64::consts::PI).sqrt();
+
+        CalcResult::Number(result)
+    }
+}

base/src/functions/statistical/poisson.rs

@@ -0,0 +1,94 @@
+use statrs::distribution::{Discrete, DiscreteCDF, Poisson};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // =POISSON.DIST(x, mean, cumulative)
+    pub(crate) fn fn_poisson_dist(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        // x
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        // mean (lambda)
+        let lambda = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[2], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if x < 0.0 || lambda < 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for POISSON.DIST".to_string(),
+            };
+        }
+
+        // Guard against insane k for u64
+        if x < 0.0 || x > (u64::MAX as f64) {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for POISSON.DIST".to_string(),
+            };
+        }
+
+        let k = x as u64;
+
+        // Special-case lambda = 0: degenerate distribution at 0
+        if lambda == 0.0 {
+            let result = if cumulative {
+                // For x >= 0, P(X <= x) = 1
+                1.0
+            } else {
+                // P(X = 0) = 1, P(X = k>0) = 0
+                if k == 0 {
+                    1.0
+                } else {
+                    0.0
+                }
+            };
+            return CalcResult::Number(result);
+        }
+
+        let dist = match Poisson::new(lambda) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for POISSON.DIST".to_string(),
+                }
+            }
+        };
+
+        let prob = if cumulative { dist.cdf(k) } else { dist.pmf(k) };
+
+        if !prob.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for POISSON.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(prob)
+    }
+}

base/src/functions/statistical/rank_eq_avg.rs

@@ -0,0 +1,202 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // Helper to collect numeric values from the 2nd argument of RANK.*
+    fn collect_rank_values(
+        &mut self,
+        arg: &Node,
+        cell: CellReferenceIndex,
+    ) -> Result<Vec<f64>, CalcResult> {
+        let values = match self.evaluate_node_in_context(arg, cell) {
+            CalcResult::Array(array) => match self.values_from_array(array) {
+                Ok(v) => v,
+                Err(e) => {
+                    return Err(CalcResult::Error {
+                        error: Error::VALUE,
+                        origin: cell,
+                        message: format!("Unsupported array argument: {}", e),
+                    })
+                }
+            },
+            CalcResult::Range { left, right } => self.values_from_range(left, right)?,
+            CalcResult::Boolean(value) => {
+                if !matches!(arg, Node::ReferenceKind { .. }) {
+                    vec![Some(if value { 1.0 } else { 0.0 })]
+                } else {
+                    return Err(CalcResult::Error {
+                        error: Error::NUM,
+                        origin: cell,
+                        message: "Unsupported argument type".to_string(),
+                    });
+                }
+            }
+            _ => {
+                return Err(CalcResult::Error {
+                    error: Error::NIMPL,
+                    origin: cell,
+                    message: "Unsupported argument type".to_string(),
+                })
+            }
+        };
+
+        let numeric_values: Vec<f64> = values.into_iter().flatten().collect();
+        Ok(numeric_values)
+    }
+
+    // RANK.EQ(number, ref, [order])
+    pub(crate) fn fn_rank_eq(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if !(2..=3).contains(&args.len()) {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        // number
+        let number = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // ref
+        let mut values = match self.collect_rank_values(&args[1], cell) {
+            Ok(v) => v,
+            Err(e) => return e,
+        };
+
+        if values.is_empty() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "No numeric values for RANK.EQ".to_string(),
+            };
+        }
+
+        // order: default 0 (descending)
+        let order = if args.len() == 2 {
+            0.0
+        } else {
+            match self.get_number_no_bools(&args[2], cell) {
+                Ok(f) => f,
+                Err(e) => return e,
+            }
+        };
+
+        values.retain(|v| !v.is_nan());
+
+        // "better" = greater (descending) or smaller (ascending)
+        let mut better = 0;
+        let mut equal = 0;
+
+        if order == 0.0 {
+            // descending
+            for v in &values {
+                if *v > number {
+                    better += 1;
+                } else if *v == number {
+                    equal += 1;
+                }
+            }
+        } else {
+            // ascending
+            for v in &values {
+                if *v < number {
+                    better += 1;
+                } else if *v == number {
+                    equal += 1;
+                }
+            }
+        }
+
+        if equal == 0 {
+            return CalcResult::Error {
+                error: Error::NA,
+                origin: cell,
+                message: "Number not found in reference for RANK.EQ".to_string(),
+            };
+        }
+
+        let rank = (better as f64) + 1.0;
+        CalcResult::Number(rank)
+    }
+
+    // RANK.AVG(number, ref, [order])
+    pub(crate) fn fn_rank_avg(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if !(2..=3).contains(&args.len()) {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        // number
+        let number = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        // ref
+        let mut values = match self.collect_rank_values(&args[1], cell) {
+            Ok(v) => v,
+            Err(e) => return e,
+        };
+
+        if values.is_empty() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "No numeric values for RANK.AVG".to_string(),
+            };
+        }
+
+        // order: default 0 (descending)
+        let order = if args.len() == 2 {
+            0.0
+        } else {
+            match self.get_number_no_bools(&args[2], cell) {
+                Ok(f) => f,
+                Err(e) => return e,
+            }
+        };
+
+        values.retain(|v| !v.is_nan());
+
+        // > or < depending on order
+        let mut better = 0;
+        let mut equal = 0;
+
+        if order == 0.0 {
+            // descending
+            for v in &values {
+                if *v > number {
+                    better += 1;
+                } else if *v == number {
+                    equal += 1;
+                }
+            }
+        } else {
+            // ascending
+            for v in &values {
+                if *v < number {
+                    better += 1;
+                } else if *v == number {
+                    equal += 1;
+                }
+            }
+        }
+
+        if equal == 0 {
+            return CalcResult::Error {
+                error: Error::NA,
+                origin: cell,
+                message: "Number not found in reference for RANK.AVG".to_string(),
+            };
+        }
+
+        // For ties, average of the ranks. If the equal values occupy positions
+        // (better+1) ..= (better+equal), the average is:
+        // better + (equal + 1) / 2
+        let better_f = better as f64;
+        let equal_f = equal as f64;
+        let rank = better_f + (equal_f + 1.0) / 2.0;
+
+        CalcResult::Number(rank)
+    }
+}

base/src/functions/statistical/standard_dev.rs

@@ -0,0 +1,519 @@
+use crate::constants::{LAST_COLUMN, LAST_ROW};
+use crate::expressions::parser::ArrayNode;
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_stdev_p(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric
+                }
+            }
+        }
+
+        if count == 0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "STDEV.P with no numeric data".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / n;
+
+        // clamp tiny negatives from FP noise
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var.sqrt())
+    }
+
+    pub(crate) fn fn_stdev_s(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric
+                }
+            }
+        }
+
+        if count <= 1 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "STDEV.S requires at least two numeric values".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / (n - 1.0);
+
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var.sqrt())
+    }
+
+    pub(crate) fn fn_stdeva(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                CalcResult::String(_) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, 0.0);
+                                }
+                                CalcResult::Boolean(value) => {
+                                    let val = if value { 1.0 } else { 0.0 };
+                                    accumulate(&mut sum, &mut sumsq, &mut count, val);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric for now
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric for now
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric for now
+                }
+            }
+        }
+
+        if count <= 1 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "STDEVA requires at least two numeric values".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / (n - 1.0);
+
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var.sqrt())
+    }
+
+    pub(crate) fn fn_stdevpa(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                CalcResult::String(_) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, 0.0);
+                                }
+                                CalcResult::Boolean(value) => {
+                                    let val = if value { 1.0 } else { 0.0 };
+                                    accumulate(&mut sum, &mut sumsq, &mut count, val);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric for now
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric for now
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric for now
+                }
+            }
+        }
+
+        if count == 0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "STDEVPA with no numeric data".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / n;
+
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var.sqrt())
+    }
+}

base/src/functions/statistical/standardize.rs

@@ -0,0 +1,38 @@
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_standardize(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        // STANDARDIZE(x, mean, standard_dev)
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let mean = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+        let std_dev = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        if std_dev <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "standard_dev must be > 0 in STANDARDIZE".to_string(),
+            };
+        }
+
+        let z = (x - mean) / std_dev;
+
+        CalcResult::Number(z)
+    }
+}

base/src/functions/statistical/t_dist.rs

@@ -0,0 +1,588 @@
+use statrs::distribution::{Continuous, ContinuousCDF, StudentsT};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+fn mean(xs: &[f64]) -> f64 {
+    let n = xs.len();
+    if n == 0 {
+        return 0.0;
+    }
+    let mut s = 0.0;
+    for &x in xs {
+        s += x;
+    }
+    s / (n as f64)
+}
+
+pub(crate) fn sample_var(xs: &[f64]) -> f64 {
+    let n = xs.len();
+    if n < 2 {
+        return 0.0;
+    }
+    let m = mean(xs);
+    let mut s = 0.0;
+    for &x in xs {
+        let d = x - m;
+        s += d * d;
+    }
+    s / ((n - 1) as f64)
+}
+
+enum TTestType {
+    Paired,
+    TwoSampleEqualVar,
+    TwoSampleUnequalVar,
+}
+
+enum TTestTails {
+    OneTailed,
+    TwoTailed,
+}
+
+impl Model {
+    // T.DIST(x, deg_freedom, cumulative)
+    pub(crate) fn fn_t_dist(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[2], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if df < 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "deg_freedom must be >= 1 in T.DIST".to_string(),
+            };
+        }
+
+        let dist = match StudentsT::new(0.0, 1.0, df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for T.DIST".to_string(),
+                }
+            }
+        };
+
+        let result = if cumulative { dist.cdf(x) } else { dist.pdf(x) };
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for T.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // T.DIST.2T(x, deg_freedom)
+    pub(crate) fn fn_t_dist_2t(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        if x < 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "x must be >= 0 in T.DIST.2T".to_string(),
+            };
+        }
+
+        if df < 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "deg_freedom must be >= 1 in T.DIST.2T".to_string(),
+            };
+        }
+
+        let dist = match StudentsT::new(0.0, 1.0, df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for T.DIST.2T".to_string(),
+                }
+            }
+        };
+
+        let upper_tail = 1.0 - dist.cdf(x);
+        let mut result = 2.0 * upper_tail;
+
+        result = result.clamp(0.0, 1.0);
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for T.DIST.2T".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // T.DIST.RT(x, deg_freedom)
+    pub(crate) fn fn_t_dist_rt(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        if df < 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "deg_freedom must be >= 1 in T.DIST.RT".to_string(),
+            };
+        }
+
+        let dist = match StudentsT::new(0.0, 1.0, df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for T.DIST.RT".to_string(),
+                }
+            }
+        };
+
+        let result = 1.0 - dist.cdf(x);
+
+        if !result.is_finite() || result < 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for T.DIST.RT".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+
+    // T.INV(probability, deg_freedom)
+    pub(crate) fn fn_t_inv(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        if p <= 0.0 || p >= 1.0 || df < 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for T.INV".to_string(),
+            };
+        }
+
+        let dist = match StudentsT::new(0.0, 1.0, df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for T.INV".to_string(),
+                }
+            }
+        };
+
+        let x = dist.inverse_cdf(p);
+
+        if !x.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for T.INV".to_string(),
+            };
+        }
+
+        CalcResult::Number(x)
+    }
+
+    // T.INV.2T(probability, deg_freedom)
+    pub(crate) fn fn_t_inv_2t(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 2 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let p = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let df = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f.trunc(),
+            Err(e) => return e,
+        };
+
+        if p <= 0.0 || p > 1.0 || df < 1.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for T.INV.2T".to_string(),
+            };
+        }
+
+        let dist = match StudentsT::new(0.0, 1.0, df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for T.INV.2T".to_string(),
+                }
+            }
+        };
+
+        // Two-sided: F(x) = 1 - p/2
+        let target_cdf = 1.0 - p / 2.0;
+        let x = dist.inverse_cdf(target_cdf);
+
+        if !x.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for T.INV.2T".to_string(),
+            };
+        }
+
+        CalcResult::Number(x.abs())
+    }
+
+    // T.TEST(array1, array2, tails, type)
+    pub(crate) fn fn_t_test(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let values1_opts = match self.evaluate_node_in_context(&args[0], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in first array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "First argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        let values2_opts = match self.evaluate_node_in_context(&args[1], cell) {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(a) => match self.values_from_array(a) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in second array: {:?}", error),
+                    );
+                }
+            },
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Second argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        let tails = match self.get_number(&args[2], cell) {
+            Ok(f) => {
+                let tf = f.trunc();
+                if tf == 1.0 {
+                    TTestTails::OneTailed
+                } else if tf == 2.0 {
+                    TTestTails::TwoTailed
+                } else {
+                    return CalcResult::new_error(
+                        Error::NUM,
+                        cell,
+                        "tails must be 1 or 2".to_string(),
+                    );
+                }
+            }
+            Err(e) => return e,
+        };
+        let test_type = match self.get_number(&args[3], cell) {
+            Ok(f) => {
+                let tf = f.trunc();
+                match tf {
+                    1.0 => TTestType::Paired,
+                    2.0 => TTestType::TwoSampleEqualVar,
+                    3.0 => TTestType::TwoSampleUnequalVar,
+                    _ => {
+                        return CalcResult::new_error(
+                            Error::NUM,
+                            cell,
+                            "type must be 1, 2, or 3".to_string(),
+                        );
+                    }
+                }
+            }
+            Err(e) => return e,
+        };
+
+        let (values1, values2): (Vec<f64>, Vec<f64>) = if matches!(test_type, TTestType::Paired) {
+            values1_opts
+                .into_iter()
+                .zip(values2_opts)
+                .filter_map(|(o1, o2)| match (o1, o2) {
+                    (Some(v1), Some(v2)) => Some((v1, v2)),
+                    _ => None, // skip if either is None
+                })
+                .unzip()
+        } else {
+            // keep only numeric entries, ignore non-numeric (Option::None)
+            let v1: Vec<f64> = values1_opts.into_iter().flatten().collect();
+            let v2: Vec<f64> = values2_opts.into_iter().flatten().collect();
+            (v1, v2)
+        };
+
+        let n1 = values1.len();
+        let n2 = values2.len();
+
+        if n1 == 0 || n2 == 0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "T.TEST requires non-empty samples".to_string(),
+            );
+        }
+
+        let (t_stat, df) = match test_type {
+            TTestType::Paired => {
+                if n1 != n2 {
+                    return CalcResult::new_error(
+                        Error::NA,
+                        cell,
+                        "For paired T.TEST, both samples must have the same length".to_string(),
+                    );
+                }
+                if n1 < 2 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Paired T.TEST requires at least two pairs".to_string(),
+                    );
+                }
+
+                let mut diffs = Vec::with_capacity(n1);
+                for i in 0..n1 {
+                    diffs.push(values1[i] - values2[i]);
+                }
+
+                let nd = diffs.len();
+                let md = mean(&diffs);
+                let vd = sample_var(&diffs);
+                if vd <= 0.0 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Zero variance in paired T.TEST".to_string(),
+                    );
+                }
+                let sd = vd.sqrt();
+                let t_stat = md / (sd / (nd as f64).sqrt());
+                let df = (nd - 1) as f64;
+                (t_stat, df)
+            }
+
+            // 2: two-sample, equal variance (homoscedastic)
+            TTestType::TwoSampleEqualVar => {
+                if n1 < 2 || n2 < 2 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Two-sample T.TEST type 2 requires at least two values in each sample"
+                            .to_string(),
+                    );
+                }
+
+                let m1 = mean(&values1);
+                let m2 = mean(&values2);
+                let v1 = sample_var(&values1);
+                let v2 = sample_var(&values2);
+
+                let df_i = (n1 + n2 - 2) as i32;
+                if df_i <= 0 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Degrees of freedom must be positive in T.TEST type 2".to_string(),
+                    );
+                }
+                let df = df_i as f64;
+
+                let sp2 = (((n1 - 1) as f64) * v1 + ((n2 - 1) as f64) * v2) / df; // pooled variance
+
+                if sp2 <= 0.0 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Zero pooled variance in T.TEST type 2".to_string(),
+                    );
+                }
+
+                let denom = (sp2 * (1.0 / (n1 as f64) + 1.0 / (n2 as f64))).sqrt();
+                if denom == 0.0 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Zero denominator in T.TEST type 2".to_string(),
+                    );
+                }
+
+                let t_stat = (m1 - m2) / denom;
+                (t_stat, df)
+            }
+
+            // two-sample, unequal variance (Welch)
+            TTestType::TwoSampleUnequalVar => {
+                if n1 < 2 || n2 < 2 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Two-sample T.TEST type 3 requires at least two values in each sample"
+                            .to_string(),
+                    );
+                }
+
+                let m1 = mean(&values1);
+                let m2 = mean(&values2);
+                let v1 = sample_var(&values1);
+                let v2 = sample_var(&values2);
+
+                let s1n = v1 / (n1 as f64);
+                let s2n = v2 / (n2 as f64);
+                let denom = (s1n + s2n).sqrt();
+                if denom == 0.0 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Zero denominator in T.TEST type 3".to_string(),
+                    );
+                }
+
+                let t_stat = (m1 - m2) / denom;
+
+                let num_df = (s1n + s2n).powi(2);
+                let den_df = (s1n * s1n) / ((n1 - 1) as f64) + (s2n * s2n) / ((n2 - 1) as f64);
+                if den_df == 0.0 {
+                    return CalcResult::new_error(
+                        Error::DIV,
+                        cell,
+                        "Invalid degrees of freedom in T.TEST type 3".to_string(),
+                    );
+                }
+                let df = num_df / den_df;
+                (t_stat, df)
+            }
+        };
+
+        if df <= 0.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "Degrees of freedom must be positive in T.TEST".to_string(),
+            );
+        }
+
+        let dist = match StudentsT::new(0.0, 1.0, df) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Invalid parameters for Student's t distribution".to_string(),
+                );
+            }
+        };
+
+        let t_abs = t_stat.abs();
+        let cdf = dist.cdf(t_abs);
+
+        let mut p = match tails {
+            TTestTails::OneTailed => 1.0 - cdf,
+            TTestTails::TwoTailed => 2.0 * (1.0 - cdf),
+        };
+
+        // clamp tiny fp noise
+        if p < 0.0 && p > -1e-15 {
+            p = 0.0;
+        }
+        if p > 1.0 && p < 1.0 + 1e-15 {
+            p = 1.0;
+        }
+
+        CalcResult::Number(p)
+    }
+}

base/src/functions/statistical/variance.rs

@@ -0,0 +1,518 @@
+use crate::constants::{LAST_COLUMN, LAST_ROW};
+use crate::expressions::parser::ArrayNode;
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    pub(crate) fn fn_var_p(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric
+                }
+            }
+        }
+
+        if count == 0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "VAR.P with no numeric data".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / n;
+
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var)
+    }
+
+    pub(crate) fn fn_var_s(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric
+                }
+            }
+        }
+
+        if count <= 1 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "VAR.S requires at least two numeric values".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / (n - 1.0);
+
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var)
+    }
+
+    pub(crate) fn fn_vara(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..=row2 {
+                        for column in column1..=column2 {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                CalcResult::String(_) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, 0.0);
+                                }
+                                CalcResult::Boolean(value) => {
+                                    let val = if value { 1.0 } else { 0.0 };
+                                    accumulate(&mut sum, &mut sumsq, &mut count, val);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric for now (A semantics to be added)
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric for now (A semantics to be added)
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric for now (A semantics to be added)
+                }
+            }
+        }
+
+        if count <= 1 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "VARA requires at least two numeric values".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / (n - 1.0);
+
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var)
+    }
+
+    pub(crate) fn fn_varpa(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        if args.is_empty() {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let mut sum = 0.0;
+        let mut sumsq = 0.0;
+        let mut count: u64 = 0;
+
+        #[inline]
+        fn accumulate(sum: &mut f64, sumsq: &mut f64, count: &mut u64, value: f64) {
+            *sum += value;
+            *sumsq += value * value;
+            *count += 1;
+        }
+
+        for arg in args {
+            match self.evaluate_node_in_context(arg, cell) {
+                CalcResult::Number(value) => {
+                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                }
+                CalcResult::Range { left, right } => {
+                    if left.sheet != right.sheet {
+                        return CalcResult::new_error(
+                            Error::VALUE,
+                            cell,
+                            "Ranges are in different sheets".to_string(),
+                        );
+                    }
+
+                    let row1 = left.row;
+                    let mut row2 = right.row;
+                    let column1 = left.column;
+                    let mut column2 = right.column;
+
+                    if row1 == 1 && row2 == LAST_ROW {
+                        row2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_row,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+                    if column1 == 1 && column2 == LAST_COLUMN {
+                        column2 = match self.workbook.worksheet(left.sheet) {
+                            Ok(s) => s.dimension().max_column,
+                            Err(_) => {
+                                return CalcResult::new_error(
+                                    Error::ERROR,
+                                    cell,
+                                    format!("Invalid worksheet index: '{}'", left.sheet),
+                                );
+                            }
+                        };
+                    }
+
+                    for row in row1..row2 + 1 {
+                        for column in column1..(column2 + 1) {
+                            match self.evaluate_cell(CellReferenceIndex {
+                                sheet: left.sheet,
+                                row,
+                                column,
+                            }) {
+                                CalcResult::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                CalcResult::String(_) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, 0.0);
+                                }
+                                CalcResult::Boolean(value) => {
+                                    let val = if value { 1.0 } else { 0.0 };
+                                    accumulate(&mut sum, &mut sumsq, &mut count, val);
+                                }
+                                error @ CalcResult::Error { .. } => return error,
+                                _ => {
+                                    // ignore non-numeric for now
+                                }
+                            }
+                        }
+                    }
+                }
+                CalcResult::Array(array) => {
+                    for row in array {
+                        for value in row {
+                            match value {
+                                ArrayNode::Number(value) => {
+                                    accumulate(&mut sum, &mut sumsq, &mut count, value);
+                                }
+                                ArrayNode::Error(error) => {
+                                    return CalcResult::Error {
+                                        error,
+                                        origin: cell,
+                                        message: "Error in array".to_string(),
+                                    }
+                                }
+                                _ => {
+                                    // ignore non-numeric for now
+                                }
+                            }
+                        }
+                    }
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    // ignore non-numeric for now
+                }
+            }
+        }
+
+        if count == 0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "VARPA with no numeric data".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mut var = (sumsq - (sum * sum) / n) / n;
+
+        if var < 0.0 && var > -1e-12 {
+            var = 0.0;
+        }
+
+        CalcResult::Number(var)
+    }
+}

base/src/functions/statistical/weibull.rs

@@ -0,0 +1,71 @@
+use statrs::distribution::{Continuous, ContinuousCDF, Weibull};
+
+use crate::expressions::types::CellReferenceIndex;
+use crate::{
+    calc_result::CalcResult, expressions::parser::Node, expressions::token::Error, model::Model,
+};
+
+impl Model {
+    // WEIBULL.DIST(x, alpha, beta, cumulative)
+    pub(crate) fn fn_weibull_dist(
+        &mut self,
+        args: &[Node],
+        cell: CellReferenceIndex,
+    ) -> CalcResult {
+        if args.len() != 4 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let x = match self.get_number_no_bools(&args[0], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let alpha = match self.get_number_no_bools(&args[1], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let beta = match self.get_number_no_bools(&args[2], cell) {
+            Ok(f) => f,
+            Err(e) => return e,
+        };
+
+        let cumulative = match self.get_boolean(&args[3], cell) {
+            Ok(b) => b,
+            Err(e) => return e,
+        };
+
+        if x < 0.0 || alpha <= 0.0 || beta <= 0.0 {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid parameters for WEIBULL.DIST".to_string(),
+            };
+        }
+
+        // statrs::Weibull: shape = k (alpha), scale = lambda (beta)
+        let dist = match Weibull::new(alpha, beta) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::Error {
+                    error: Error::NUM,
+                    origin: cell,
+                    message: "Invalid parameters for WEIBULL.DIST".to_string(),
+                }
+            }
+        };
+
+        let result = if cumulative { dist.cdf(x) } else { dist.pdf(x) };
+
+        if !result.is_finite() {
+            return CalcResult::Error {
+                error: Error::NUM,
+                origin: cell,
+                message: "Invalid result for WEIBULL.DIST".to_string(),
+            };
+        }
+
+        CalcResult::Number(result)
+    }
+}

base/src/functions/statistical/z_test.rs

@@ -0,0 +1,171 @@
+use statrs::distribution::{ContinuousCDF, Normal};
+
+use crate::expressions::token::Error;
+use crate::expressions::types::CellReferenceIndex;
+use crate::{calc_result::CalcResult, expressions::parser::Node, model::Model};
+
+impl Model {
+    // Z.TEST(array, x, [sigma])
+    pub(crate) fn fn_z_test(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
+        // 2 or 3 arguments
+        if args.len() < 2 || args.len() > 3 {
+            return CalcResult::new_args_number_error(cell);
+        }
+
+        let array_arg = self.evaluate_node_in_context(&args[0], cell);
+
+        // Flatten first argument into Vec<Option<f64>> (numeric / non-numeric)
+        let values = match array_arg {
+            CalcResult::Range { left, right } => match self.values_from_range(left, right) {
+                Ok(v) => v,
+                Err(error) => return error,
+            },
+            CalcResult::Array(array) => match self.values_from_array(array) {
+                Ok(v) => v,
+                Err(error) => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        format!("Error in array argument: {:?}", error),
+                    );
+                }
+            },
+            CalcResult::Number(v) => vec![Some(v)],
+            error @ CalcResult::Error { .. } => return error,
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Z.TEST first argument must be a range or array".to_string(),
+                );
+            }
+        };
+
+        // Collect basic stats on numeric entries
+        let mut sum = 0.0;
+        let mut count: u64 = 0;
+
+        for x in values.iter().flatten() {
+            sum += x;
+            count += 1;
+        }
+
+        // Excel: if array has no numeric values -> #N/A
+        if count == 0 {
+            return CalcResult::new_error(
+                Error::NA,
+                cell,
+                "Z.TEST array has no numeric data".to_string(),
+            );
+        }
+
+        let n = count as f64;
+        let mean = sum / n;
+
+        // x argument (hypothesized population mean)
+        let x_value = match self.evaluate_node_in_context(&args[1], cell) {
+            CalcResult::Number(v) => v,
+            error @ CalcResult::Error { .. } => return error,
+            _ => {
+                return CalcResult::new_error(
+                    Error::VALUE,
+                    cell,
+                    "Z.TEST second argument (x) must be numeric".to_string(),
+                );
+            }
+        };
+
+        // Optional sigma
+        let mut sigma: Option<f64> = None;
+        if args.len() == 3 {
+            match self.evaluate_node_in_context(&args[2], cell) {
+                CalcResult::Number(v) => {
+                    if v == 0.0 {
+                        return CalcResult::new_error(
+                            Error::NUM,
+                            cell,
+                            "Z.TEST sigma cannot be zero".to_string(),
+                        );
+                    }
+                    sigma = Some(v);
+                }
+                error @ CalcResult::Error { .. } => return error,
+                _ => {
+                    return CalcResult::new_error(
+                        Error::VALUE,
+                        cell,
+                        "Z.TEST sigma (third argument) must be numeric".to_string(),
+                    );
+                }
+            }
+        }
+
+        // If sigma omitted, use sample standard deviation STDEV(array)
+        let sigma_value = if let Some(s) = sigma {
+            s
+        } else {
+            // Excel: if only one numeric value and sigma omitted -> #DIV/0!
+            if count <= 1 {
+                return CalcResult::new_error(
+                    Error::DIV,
+                    cell,
+                    "Z.TEST requires at least two values when sigma is omitted".to_string(),
+                );
+            }
+
+            // Compute sum of squared deviations
+            let mut sumsq_dev = 0.0;
+            for x in values.iter().flatten() {
+                let d = x - mean;
+                sumsq_dev += d * d;
+            }
+
+            let var = sumsq_dev / (n - 1.0);
+            if var <= 0.0 {
+                return CalcResult::new_error(
+                    Error::DIV,
+                    cell,
+                    "Z.TEST standard deviation is zero".to_string(),
+                );
+            }
+
+            var.sqrt()
+        };
+
+        // Compute z statistic: (mean - x) / (sigma / sqrt(n))
+        let denom = sigma_value / n.sqrt();
+        if denom == 0.0 {
+            return CalcResult::new_error(
+                Error::DIV,
+                cell,
+                "Z.TEST denominator is zero".to_string(),
+            );
+        }
+
+        let z = (mean - x_value) / denom;
+
+        // Standard normal CDF
+        let dist = match Normal::new(0.0, 1.0) {
+            Ok(d) => d,
+            Err(_) => {
+                return CalcResult::new_error(
+                    Error::NUM,
+                    cell,
+                    "Cannot create standard normal distribution in Z.TEST".to_string(),
+                );
+            }
+        };
+
+        let mut p = 1.0 - dist.cdf(z);
+
+        // clamp tiny FP noise
+        if p < 0.0 && p > -1e-15 {
+            p = 0.0;
+        }
+        if p > 1.0 && p < 1.0 + 1e-15 {
+            p = 1.0;
+        }
+
+        CalcResult::Number(p)
+    }
+}

base/src/functions/util.rs

@@ -1,7 +1,10 @@
 #[cfg(feature = "use_regex_lite")]
 use regex_lite as regex;
 
-use crate::{calc_result::CalcResult, expressions::token::is_english_error_string};
+use crate::{
+    calc_result::CalcResult, expressions::token::is_english_error_string,
+    number_format::to_excel_precision,
+};
 
 /// This test for exact match (modulo case).
 ///   * strings are not cast into bools or numbers
@@ -34,6 +37,8 @@ pub(crate) fn values_are_equal(left: &CalcResult, right: &CalcResult) -> bool {
 pub(crate) fn compare_values(left: &CalcResult, right: &CalcResult) -> i32 {
     match (left, right) {
         (CalcResult::Number(value1), CalcResult::Number(value2)) => {
+            let value1 = to_excel_precision(*value1, 15);
+            let value2 = to_excel_precision(*value2, 15);
             if (value2 - value1).abs() < f64::EPSILON {
                 return 0;
             }

base/src/model.rs

@@ -2068,21 +2068,7 @@ impl Model {
         scope: Option<u32>,
         formula: &str,
     ) -> Result<(), String> {
-        if !is_valid_identifier(name) {
-            return Err("Invalid defined name".to_string());
-        };
-        let name_upper = name.to_uppercase();
-        let defined_names = &self.workbook.defined_names;
-        let sheet_id = match scope {
-            Some(index) => Some(self.workbook.worksheet(index)?.sheet_id),
-            None => None,
-        };
-        // if the defined name already exist return error
-        for df in defined_names {
-            if df.name.to_uppercase() == name_upper && df.sheet_id == sheet_id {
-                return Err("Defined name already exists".to_string());
-            }
-        }
+        let sheet_id = self.is_valid_defined_name(name, scope, formula)?;
         self.workbook.defined_names.push(DefinedName {
             name: name.to_string(),
             formula: formula.to_string(),
@@ -2093,6 +2079,48 @@ impl Model {
         Ok(())
     }
 
+    /// Validates if a defined name can be created
+    pub fn is_valid_defined_name(
+        &self,
+        name: &str,
+        scope: Option<u32>,
+        formula: &str,
+    ) -> Result<Option<u32>, String> {
+        if !is_valid_identifier(name) {
+            return Err("Name: Invalid defined name".to_string());
+        }
+        let name_upper = name.to_uppercase();
+        let defined_names = &self.workbook.defined_names;
+        let sheet_id = match scope {
+            Some(index) => match self.workbook.worksheet(index) {
+                Ok(ws) => Some(ws.sheet_id),
+                Err(_) => return Err("Scope: Invalid sheet index".to_string()),
+            },
+            None => None,
+        };
+        // if the defined name already exist return error
+        for df in defined_names {
+            if df.name.to_uppercase() == name_upper && df.sheet_id == sheet_id {
+                return Err("Name: Defined name already exists".to_string());
+            }
+        }
+
+        // Make sure the formula is valid
+        match common::ParsedReference::parse_reference_formula(
+            None,
+            formula,
+            &self.locale,
+            |name| self.get_sheet_index_by_name(name),
+        ) {
+            Ok(_) => {}
+            Err(_) => {
+                return Err("Formula: Invalid defined name formula".to_string());
+            }
+        };
+
+        Ok(sheet_id)
+    }
+
     /// Delete defined name of name and scope
     pub fn delete_defined_name(&mut self, name: &str, scope: Option<u32>) -> Result<(), String> {
         let name_upper = name.to_uppercase();
@@ -2126,7 +2154,7 @@ impl Model {
         new_formula: &str,
     ) -> Result<(), String> {
         if !is_valid_identifier(new_name) {
-            return Err("Invalid defined name".to_string());
+            return Err("Name: Invalid defined name".to_string());
         };
         let name_upper = name.to_uppercase();
         let new_name_upper = new_name.to_uppercase();
@@ -2134,18 +2162,28 @@ impl Model {
         if name_upper != new_name_upper || scope != new_scope {
             for key in self.parsed_defined_names.keys() {
                 if key.1.to_uppercase() == new_name_upper && key.0 == new_scope {
-                    return Err("Defined name already exists".to_string());
+                    return Err("Name: Defined name already exists".to_string());
                 }
             }
         }
         let defined_names = &self.workbook.defined_names;
         let sheet_id = match scope {
-            Some(index) => Some(self.workbook.worksheet(index)?.sheet_id),
+            Some(index) => Some(
+                self.workbook
+                    .worksheet(index)
+                    .map_err(|_| "Scope: Invalid sheet index")?
+                    .sheet_id,
+            ),
             None => None,
         };
 
         let new_sheet_id = match new_scope {
-            Some(index) => Some(self.workbook.worksheet(index)?.sheet_id),
+            Some(index) => Some(
+                self.workbook
+                    .worksheet(index)
+                    .map_err(|_| "Scope: Invalid sheet index")?
+                    .sheet_id,
+            ),
             None => None,
         };
 

base/src/number_format.rs

@@ -112,29 +112,36 @@ pub fn to_precision(value: f64, precision: usize) -> f64 {
 /// ```
 /// This intends to be equivalent to the js: `${parseFloat(value.toPrecision(precision)})`
 /// See ([ecma](https://tc39.es/ecma262/#sec-number.prototype.toprecision)).
-/// FIXME: There has to be a better algorithm :/
 pub fn to_excel_precision_str(value: f64) -> String {
     to_precision_str(value, 15)
 }
+
+pub fn to_excel_precision(value: f64, precision: usize) -> f64 {
+    if !value.is_finite() {
+        return value;
+    }
+
+    let s = format!("{:.*e}", precision.saturating_sub(1), value);
+    s.parse::<f64>().unwrap_or(value)
+}
+
 pub fn to_precision_str(value: f64, precision: usize) -> String {
+    if !value.is_finite() {
         if value.is_infinite() {
             return "inf".to_string();
-    }
-    if value.is_nan() {
+        } else {
             return "NaN".to_string();
         }
-    let exponent = value.abs().log10().floor();
-    let base = value / 10.0_f64.powf(exponent);
-    let base = format!("{0:.1$}", base, precision - 1);
-    let value = format!("{base}e{exponent}").parse::<f64>().unwrap_or({
-        // TODO: do this in a way that does not require a possible error
-        0.0
-    });
+    }
+
+    let s = format!("{:.*e}", precision.saturating_sub(1), value);
+    let parsed = s.parse::<f64>().unwrap_or(value);
+
     // I would love to use the std library. There is not a speed concern here
     // problem is it doesn't do the right thing
     // Also ryu is my favorite _modern_ algorithm
     let mut buffer = ryu::Buffer::new();
-    let text = buffer.format(value);
+    let text = buffer.format(parsed);
     // The above algorithm converts 2 to 2.0 regrettably
     if let Some(stripped) = text.strip_suffix(".0") {
         return stripped.to_string();

base/src/test/engineering/test_complex.rs

@@ -133,6 +133,7 @@ fn fn_imcot() {
     );
 }
 
+#[cfg_attr(target_os = "windows", ignore)]
 #[test]
 fn fn_imtan() {
     let mut model = new_empty_model();

base/src/test/mod.rs

@@ -7,6 +7,9 @@ mod test_column_width;
 mod test_criteria;
 mod test_currency;
 mod test_date_and_time;
+mod test_datedif_leap_month_end;
+mod test_days360_month_end;
+mod test_degrees_radians;
 mod test_error_propagation;
 mod test_fn_average;
 mod test_fn_averageifs;
@@ -27,6 +30,7 @@ mod test_fn_sum;
 mod test_fn_sumifs;
 mod test_fn_textbefore;
 mod test_fn_textjoin;
+mod test_fn_time;
 mod test_fn_unicode;
 mod test_frozen_rows_columns;
 mod test_general;
@@ -41,19 +45,29 @@ mod test_set_user_input;
 mod test_sheet_markup;
 mod test_sheets;
 mod test_styles;
+mod test_sumsq;
 mod test_trigonometric;
 mod test_true_false;
+mod test_weekday_return_types;
+mod test_weeknum_return_types;
 mod test_workbook;
 mod test_worksheet;
+mod test_yearfrac_basis;
 pub(crate) mod util;
 
 mod engineering;
+mod statistical;
 mod test_fn_offset;
 mod test_number_format;
 
 mod test_arrays;
+mod test_combin_combina;
 mod test_escape_quotes;
+mod test_even_odd;
+mod test_exp_sign;
 mod test_extend;
+mod test_floor;
+mod test_fn_datevalue_timevalue;
 mod test_fn_fv;
 mod test_fn_round;
 mod test_fn_type;
@@ -62,11 +76,17 @@ mod test_geomean;
 mod test_get_cell_content;
 mod test_implicit_intersection;
 mod test_issue_155;
+mod test_issue_483;
 mod test_ln;
 mod test_log;
 mod test_log10;
+mod test_mod_quotient;
+mod test_networkdays;
+mod test_now;
 mod test_percentage;
 mod test_set_functions_error_handling;
+mod test_sheet_names;
 mod test_today;
+mod test_trigonometric_reciprocals;
 mod test_types;
 mod user_model;

base/src/test/statistical/mod.rs

@@ -0,0 +1,24 @@
+mod test_fn_avedev;
+mod test_fn_binom;
+mod test_fn_chisq;
+mod test_fn_chisq_test;
+mod test_fn_confidence;
+mod test_fn_covariance;
+mod test_fn_devsq;
+mod test_fn_expon_dist;
+mod test_fn_f;
+mod test_fn_f_test;
+mod test_fn_fisher;
+mod test_fn_gauss;
+mod test_fn_hyp_geom_dist;
+mod test_fn_log_norm;
+mod test_fn_norm_dist;
+mod test_fn_pearson;
+mod test_fn_phi;
+mod test_fn_poisson;
+mod test_fn_stdev;
+mod test_fn_t_dist;
+mod test_fn_t_test;
+mod test_fn_var;
+mod test_fn_weibull;
+mod test_fn_z_test;

base/src/test/statistical/test_fn_avedev.rs

@@ -0,0 +1,40 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn smoke_test() {
+    let mut model = new_empty_model();
+    model._set("A1", "=STDEV.P(10, 12, 23, 23, 16, 23, 21)");
+    model._set("A2", "=STDEV.S(10, 12, 23, 23, 16, 23, 21)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"5.174505793");
+
+    assert_eq!(model._get_text("A2"), *"5.589105048");
+}
+
+#[test]
+fn numbers() {
+    let mut model = new_empty_model();
+
+    model._set("A2", "24");
+    model._set("A3", "25");
+    model._set("A4", "27");
+    model._set("A5", "23");
+    model._set("A6", "45");
+    model._set("A7", "23.5");
+    model._set("A8", "34");
+    model._set("A9", "23");
+    model._set("A10", "23");
+    model._set("A11", "TRUE");
+    model._set("A12", "'23");
+    model._set("A13", "Text");
+    model._set("A14", "FALSE");
+    model._set("A15", "45");
+
+    model._set("B1", "=AVEDEV(A2:A15)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("B1"), *"7.25");
+}

base/src/test/statistical/test_fn_binom.rs

@@ -0,0 +1,86 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_binom_dist_smoke() {
+    let mut model = new_empty_model();
+    model._set("A1", "=BINOM.DIST(6, 10, 0.5, TRUE)");
+    model._set("A2", "=BINOM.DIST(6, 10, 0.5, FALSE)");
+    model._set("A3", "=BINOM.DIST(6, 10, 0.5)"); // wrong args
+    model._set("A4", "=BINOM.DIST(6, 10, 0.5, TRUE, FALSE)"); // too many args
+    model.evaluate();
+
+    // P(X <= 6) for X ~ Bin(10, 0.5) = 0.828125
+    assert_eq!(model._get_text("A1"), *"0.828125");
+
+    // P(X = 6) for X ~ Bin(10, 0.5) = 0.205078125
+    assert_eq!(model._get_text("A2"), *"0.205078125");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+}
+
+#[test]
+fn test_fn_binom_dist_range_smoke() {
+    let mut model = new_empty_model();
+    model._set("A1", "=BINOM.DIST.RANGE(60, 0.75, 48)");
+    model._set("A2", "=BINOM.DIST.RANGE(60, 0.75, 45, 50)");
+    model._set("A3", "=BINOM.DIST.RANGE(60, 1.2, 45, 50)"); // p > 1 -> #NUM!
+    model._set("A4", "=BINOM.DIST.RANGE(60, 0.75, 50, 45)"); // lower > upper -> #NUM!");
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.083974967");
+
+    assert_eq!(model._get_text("A2"), *"0.523629793");
+
+    assert_eq!(model._get_text("A3"), *"#NUM!");
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_binom_inv_smoke() {
+    let mut model = new_empty_model();
+    model._set("A1", "=BINOM.INV(6, 0.5, 0.75)");
+    model._set("A2", "=BINOM.INV(6, 0.5, -0.1)"); // alpha < 0 -> #NUM!
+    model._set("A3", "=BINOM.INV(6, 1.2, 0.75)"); // p > 1 -> #NUM!
+    model._set("A4", "=BINOM.INV(6, 0.5)"); // args error
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"4");
+    assert_eq!(model._get_text("A2"), *"#NUM!");
+    assert_eq!(model._get_text("A3"), *"#NUM!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+}
+
+#[test]
+fn test_fn_negbinom_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: PMF (non-cumulative) and CDF (cumulative)
+    model._set("A1", "=NEGBINOM.DIST(10, 5, 0.25, FALSE)");
+    model._set("A2", "=NEGBINOM.DIST(10, 5, 0.25, TRUE)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A3", "=NEGBINOM.DIST(10, 5, 0.25)");
+    model._set("A4", "=NEGBINOM.DIST(10, 5, 0.25, TRUE, FALSE)");
+
+    // Domain errors:
+    // p < 0 or p > 1 -> #NUM!
+    model._set("A5", "=NEGBINOM.DIST(10, 5, 1.5, TRUE)");
+    // number_f < 0 -> #NUM!
+    model._set("A6", "=NEGBINOM.DIST(-1, 5, 0.25, TRUE)");
+    // number_s < 1 -> #NUM!
+    model._set("A7", "=NEGBINOM.DIST(10, 0, 0.25, TRUE)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.05504866");
+    assert_eq!(model._get_text("A2"), *"0.313514058");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+}

base/src/test/statistical/test_fn_chisq.rs

@@ -0,0 +1,140 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_chisq_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: CDF
+    model._set("A1", "=CHISQ.DIST(0.5, 4, TRUE)");
+
+    // Valid: PDF
+    model._set("A2", "=CHISQ.DIST(0.5, 4, FALSE)");
+
+    // Valid: CDF with numeric cumulative (1 -> TRUE)
+    model._set("A3", "=CHISQ.DIST(0.5, 4, 1)");
+
+    // Wrong number of args -> #ERROR!
+    model._set("A4", "=CHISQ.DIST(0.5, 4)");
+    model._set("A5", "=CHISQ.DIST(0.5, 4, TRUE, FALSE)");
+
+    // Domain errors
+    // x < 0 -> #NUM!
+    model._set("A6", "=CHISQ.DIST(-1, 4, TRUE)");
+    // deg_freedom < 1 -> #NUM!
+    model._set("A7", "=CHISQ.DIST(0.5, 0, TRUE)");
+
+    model.evaluate();
+
+    // Values for df = 4
+    // CDF(0.5) ≈ 0.026499021, PDF(0.5) ≈ 0.097350098
+    assert_eq!(model._get_text("A1"), *"0.026499021");
+    assert_eq!(model._get_text("A2"), *"0.097350098");
+    assert_eq!(model._get_text("A3"), *"0.026499021");
+
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#ERROR!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_chisq_dist_rt_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid calls
+    model._set("A1", "=CHISQ.DIST.RT(0.5, 4)");
+    model._set("A2", "=CHISQ.DIST.RT(5, 4)");
+
+    // Too few / too many args -> #ERROR!
+    model._set("A3", "=CHISQ.DIST.RT(0.5)");
+    model._set("A4", "=CHISQ.DIST.RT(0.5, 4, 1)");
+
+    // Domain errors
+    // x < 0 -> #NUM!
+    model._set("A5", "=CHISQ.DIST.RT(-1, 4)");
+    // deg_freedom < 1 -> #NUM!
+    model._set("A6", "=CHISQ.DIST.RT(0.5, 0)");
+
+    model.evaluate();
+
+    // For df = 4:
+    // right tail at 0.5 ≈ 0.973500979
+    // right tail at 5.0 ≈ 0.287297495
+    assert_eq!(model._get_text("A1"), *"0.973500979");
+    assert_eq!(model._get_text("A2"), *"0.287297495");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_chisq_inv_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid calls
+    model._set("A1", "=CHISQ.INV(0.95, 4)");
+    model._set("A2", "=CHISQ.INV(0.1, 10)");
+
+    // Wrong number of args -> #ERROR!
+    model._set("A3", "=CHISQ.INV(0.95)");
+    model._set("A4", "=CHISQ.INV(0.95, 4, 1)");
+
+    // Domain errors
+    // probability < 0 or > 1 -> #NUM!
+    model._set("A5", "=CHISQ.INV(-0.1, 4)");
+    model._set("A6", "=CHISQ.INV(1.1, 4)");
+    // deg_freedom < 1 -> #NUM!
+    model._set("A7", "=CHISQ.INV(0.5, 0)");
+
+    model.evaluate();
+
+    // Standard critical values:
+    // CHISQ.INV(0.95, 4) ≈ 9.487729037
+    // CHISQ.INV(0.1, 10) ≈ 4.865182052
+    assert_eq!(model._get_text("A1"), *"9.487729037");
+    assert_eq!(model._get_text("A2"), *"4.865182052");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_chisq_inv_rt_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid calls
+    model._set("A1", "=CHISQ.INV.RT(0.05, 4)");
+    model._set("A2", "=CHISQ.INV.RT(0.9, 10)");
+
+    // Wrong number of args -> #ERROR!
+    model._set("A3", "=CHISQ.INV.RT(0.05)");
+    model._set("A4", "=CHISQ.INV.RT(0.05, 4, 1)");
+
+    // Domain errors
+    // probability < 0 or > 1 -> #NUM!
+    model._set("A5", "=CHISQ.INV.RT(-0.1, 4)");
+    model._set("A6", "=CHISQ.INV.RT(1.1, 4)");
+    // deg_freedom < 1 -> #NUM!
+    model._set("A7", "=CHISQ.INV.RT(0.5, 0)");
+
+    model.evaluate();
+
+    // For chi-square:
+    // CHISQ.INV.RT(0.05, 4) = CHISQ.INV(0.95, 4) ≈ 9.487729037
+    // CHISQ.INV.RT(0.9, 10)  = CHISQ.INV(0.1, 10) ≈ 4.865182052
+    assert_eq!(model._get_text("A1"), *"9.487729037");
+    assert_eq!(model._get_text("A2"), *"4.865182052");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+}

base/src/test/statistical/test_fn_chisq_test.rs

@@ -0,0 +1,127 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_chisq_test_smoke() {
+    let mut model = new_empty_model();
+    model._set("A2", "48");
+    model._set("A3", "32");
+    model._set("A4", "12");
+    model._set("A5", "1");
+    model._set("A6", "'13");
+    model._set("A7", "TRUE");
+    model._set("A8", "1");
+    model._set("A9", "13");
+    model._set("A10", "15");
+
+    model._set("B2", "55");
+    model._set("B3", "34");
+    model._set("B4", "13");
+    model._set("B5", "blah");
+    model._set("B6", "13");
+    model._set("B7", "1");
+    model._set("B8", "TRUE");
+    model._set("B9", "'14");
+    model._set("B10", "16");
+
+    model._set("C1", "=CHISQ.TEST(A2:A10, B2:B10)");
+    model.evaluate();
+    assert_eq!(model._get_text("C1"), *"0.997129538");
+}
+
+#[test]
+fn arrays() {
+    let mut model = new_empty_model();
+    model._set("A2", "TRUE");
+    model._set("A3", "4");
+    model._set("A4", "'3");
+    model._set("B2", "2");
+    model._set("B3", "2");
+    model._set("B4", "2");
+    model._set("C1", "=CHISQ.TEST(A2:A4, B2:B4)");
+
+    model._set("G5", "=CHISQ.TEST({TRUE,4,\"3\"}, {2,2,2})");
+
+    // 1D arrays with different shapes
+    model._set("G6", "=CHISQ.TEST({1,2,3}, {3;3;4})");
+
+    // 2D array
+    model._set("G7", "=CHISQ.TEST({1,2;3,4},{2,3;2,2})");
+
+    // 1D arrays with same shape
+    model._set("G8", "=CHISQ.TEST({1,2,3,4}, {2,3,4,5})");
+
+    model.evaluate();
+    assert_eq!(model._get_text("C1"), *"0.367879441");
+    assert_eq!(model._get_text("G5"), *"0.367879441");
+
+    assert_eq!(model._get_text("G6"), *"0.383531573");
+
+    assert_eq!(model._get_text("G7"), *"0.067889155");
+
+    assert_eq!(model._get_text("G8"), *"0.733094495");
+}
+
+#[test]
+fn more_arrays() {
+    let mut model = new_empty_model();
+    model._set("V20", "2");
+    model._set("V21", "4");
+    model._set("W20", "3");
+    model._set("W21", "5");
+    model._set("C1", "=CHISQ.TEST({1,2;3,4},V20:W21)");
+    model._set("C2", "=CHISQ.TEST({1,2;3,4}, {2,3;4,5})");
+    model.evaluate();
+    assert_eq!(model._get_text("C1"), *"0.257280177");
+    assert_eq!(model._get_text("C2"), *"0.257280177");
+}
+
+#[test]
+fn array_ranges() {
+    let mut model = new_empty_model();
+    model._set("A2", "TRUE");
+    model._set("A3", "4");
+    model._set("A4", "'3");
+    model._set("B2", "2");
+    model._set("B3", "2");
+    model._set("B4", "2");
+    model._set("C1", "=CHISQ.TEST(A2:A4, {2;2;2})");
+
+    model._set("G5", "=CHISQ.TEST({TRUE;4;\"3\"}, B2:B4)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("C1"), *"0.367879441");
+    assert_eq!(model._get_text("G5"), *"0.367879441");
+}
+
+#[test]
+fn array_2d_ranges() {
+    let mut model = new_empty_model();
+    model._set("A2", "2");
+    model._set("B2", "3");
+    model._set("C2", "4");
+    model._set("A3", "5");
+    model._set("B3", "6");
+    model._set("C3", "7");
+    model._set("G1", "=CHISQ.TEST({1,2,3;4,2,6}, A2:C3)");
+    model.evaluate();
+    assert_eq!(model._get_text("G1"), *"0.129195493");
+}
+
+#[test]
+fn ranges_1d() {
+    let mut model = new_empty_model();
+    model._set("A2", "1");
+    model._set("A3", "2");
+    model._set("A4", "3");
+    model._set("B2", "4");
+    model._set("C2", "5");
+    model._set("D2", "6");
+    model._set("G1", "=CHISQ.TEST(A2:A4, B2:D2)");
+    model._set("G2", "=CHISQ.TEST(B2:D2, A2:A4)");
+
+    model.evaluate();
+    assert_eq!(model._get_text("G1"), *"0.062349477");
+    assert_eq!(model._get_text("G2"), *"0.000261259");
+}

base/src/test/statistical/test_fn_confidence.rs

@@ -0,0 +1,51 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_confidence_norm_smoke() {
+    let mut model = new_empty_model();
+
+    model._set("A1", "=CONFIDENCE.NORM(0.05, 2.5, 50)");
+
+    // Some edge/error cases
+    model._set("A2", "=CONFIDENCE.NORM(0, 2.5, 50)"); // alpha <= 0  -> #NUM!
+    model._set("A3", "=CONFIDENCE.NORM(1, 2.5, 50)"); // alpha >= 1  -> #NUM!
+    model._set("A4", "=CONFIDENCE.NORM(0.05, -1, 50)"); // std_dev <=0 -> #NUM!
+    model._set("A5", "=CONFIDENCE.NORM(0.05, 2.5, 1)");
+    model._set("A6", "=CONFIDENCE.NORM(0.05, 2.5, 0.99)"); // size < 1 -> #NUM!
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.692951912");
+
+    assert_eq!(model._get_text("A2"), *"#NUM!");
+    assert_eq!(model._get_text("A3"), *"#NUM!");
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+    assert_eq!(model._get_text("A5"), *"4.899909961");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_confidence_t_smoke() {
+    let mut model = new_empty_model();
+
+    model._set("A1", "=CONFIDENCE.T(0.05, 50000, 100)");
+
+    // Some edge/error cases
+    model._set("A2", "=CONFIDENCE.T(0, 50000, 100)"); // alpha <= 0 -> #NUM!
+    model._set("A3", "=CONFIDENCE.T(1, 50000, 100)"); // alpha >= 1 -> #NUM!
+    model._set("A4", "=CONFIDENCE.T(0.05, -1, 100)");
+    model._set("A5", "=CONFIDENCE.T(0.05, 50000, 1)");
+    model._set("A6", "=CONFIDENCE.T(0.05, 50000, 1.7)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"9921.08475793");
+
+    assert_eq!(model._get_text("A2"), *"#NUM!");
+    assert_eq!(model._get_text("A3"), *"#NUM!");
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+    assert_eq!(model._get_text("A5"), *"#DIV/0!");
+    assert_eq!(model._get_text("A6"), *"#DIV/0!");
+}

base/src/test/statistical/test_fn_covariance.rs

@@ -0,0 +1,57 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_covariance_smoke() {
+    let mut model = new_empty_model();
+    model._set("A1", "3");
+    model._set("A2", "9");
+    model._set("A3", "2");
+    model._set("A4", "7");
+    model._set("A5", "4");
+    model._set("A6", "12");
+
+    model._set("B1", "5");
+    model._set("B2", "15");
+    model._set("B3", "6");
+    model._set("B4", "17");
+    model._set("B5", "8");
+    model._set("B6", "20");
+
+    model._set("C1", "=COVARIANCE.P(A1:A6, B1:B6)");
+    model._set("C2", "=COVARIANCE.S(A1:A6, B1:B6)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("C1"), *"19.194444444");
+    assert_eq!(model._get_text("C2"), *"23.033333333");
+}
+
+#[test]
+fn arrays_mixed() {
+    let mut model = new_empty_model();
+
+    model._set("A2", "2");
+    model._set("A3", "4");
+    model._set("A4", "6");
+    model._set("A5", "8");
+
+    model._set("B2", "1");
+    model._set("B3", "3");
+    model._set("B4", "5");
+    model._set("B5", "7");
+
+    model._set("C1", "=COVARIANCE.P(A2:A5, {1,3,5,7})");
+    model._set("C2", "=COVARIANCE.S(A2:A5, {1,3,5,7})");
+    model._set("C3", "=COVARIANCE.P(A2:A5, B2:B5)");
+    model._set("C4", "=COVARIANCE.S(A2:A5, B2:B5)");
+    model._set("C5", "=COVARIANCE.P({2,4,6,8}, B2:B5)");
+    model._set("C6", "=COVARIANCE.S({2,4,6,8}, B2:B5)");
+    model._set("C7", "=COVARIANCE.P({2,4,6,8}, {1,3,5,7})");
+    model._set("C8", "=COVARIANCE.S({2,4,6,8}, {1,3,5,7})");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("C1"), *"5");
+    assert_eq!(model._get_text("C2"), *"6.666666667");
+}

base/src/test/statistical/test_fn_devsq.rs

@@ -0,0 +1,50 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn arguments_smoke_test() {
+    let mut model = new_empty_model();
+    model._set("A1", "=DEVSQ()");
+    model._set("A2", "=DEVSQ(1, 2, 3)");
+    model._set("A3", "=DEVSQ(1, )");
+    model._set("A4", "=DEVSQ(1,   , 3)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"#ERROR!");
+    assert_eq!(model._get_text("A2"), *"2");
+    assert_eq!(model._get_text("A3"), *"0");
+    assert_eq!(model._get_text("A4"), *"2");
+}
+
+#[test]
+fn ranges() {
+    let mut model = new_empty_model();
+    model._set("A1", "=DEVSQ(A2:A8)");
+    model._set("A2", "4");
+    model._set("A3", "5");
+    model._set("A4", "8");
+    model._set("A5", "7");
+    model._set("A6", "11");
+    model._set("A7", "4");
+    model._set("A8", "3");
+    model.evaluate();
+    assert_eq!(model._get_text("A1"), *"48");
+}
+
+#[test]
+fn arrays() {
+    let mut model = new_empty_model();
+    model._set("A1", "=DEVSQ({1, 2, 3})");
+    model._set("A2", "=DEVSQ({1; 2; 3})");
+    model._set("A3", "=DEVSQ({1, 2; 3, 4})");
+    model._set("A4", "=DEVSQ({1, 2; 3, 4; 5, 6})");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"2");
+    assert_eq!(model._get_text("A2"), *"2");
+    assert_eq!(model._get_text("A3"), *"5");
+    assert_eq!(model._get_text("A4"), *"17.5");
+}

base/src/test/statistical/test_fn_expon_dist.rs

@@ -0,0 +1,32 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_expon_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // λ = 1, x = 0.5
+    // CDF = 1 - e^-0.5 ≈ 0.393469340
+    // PDF = e^-0.5 ≈ 0.606530660
+    model._set("A1", "=EXPON.DIST(0.5, 1, TRUE)");
+    model._set("A2", "=EXPON.DIST(0.5, 1, FALSE)");
+
+    // Wrong number of args
+    model._set("A3", "=EXPON.DIST(0.5, 1)");
+    model._set("A4", "=EXPON.DIST(0.5, 1, TRUE, FALSE)");
+
+    // Domain errors
+    model._set("A5", "=EXPON.DIST(-1, 1, TRUE)"); // x < 0
+    model._set("A6", "=EXPON.DIST(0.5, 0, TRUE)"); // lambda <= 0
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.39346934");
+    assert_eq!(model._get_text("A2"), *"0.60653066");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}

base/src/test/statistical/test_fn_f.rs

@@ -0,0 +1,75 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_f_dist_sanity() {
+    let mut model = new_empty_model();
+    model._set("A1", "=F.DIST(15, 6, 4, TRUE)");
+    model._set("A2", "=F.DIST(15, 6, 4, FALSE)");
+    model._set("A3", "=F.DIST(15, 6, 4)");
+    model._set("A4", "=F.DIST(15, 6, 4, TRUE, FALSE)");
+    model.evaluate();
+    assert_eq!(model._get_text("A1"), *"0.989741952");
+    assert_eq!(model._get_text("A2"), *"0.001271447");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+}
+
+#[test]
+fn test_fn_f_dist_rt_sanity() {
+    let mut model = new_empty_model();
+
+    // Valid call
+    model._set("A1", "=F.DIST.RT(15, 6, 4)");
+    // Too few args
+    model._set("A2", "=F.DIST.RT(15, 6)");
+    // Too many args
+    model._set("A3", "=F.DIST.RT(15, 6, 4, 1)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.010258048");
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+}
+
+#[test]
+fn test_fn_f_inv_sanity() {
+    let mut model = new_empty_model();
+
+    // Valid call: left-tail inverse
+    model._set("A1", "=F.INV(0.9897419523940, 6, 4)");
+
+    // Too many args
+    model._set("A2", "=F.INV(0.5, 6, 4, 2)");
+
+    // Too few args
+    model._set("A3", "=F.INV(0.5, 6)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"15");
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+}
+
+#[test]
+fn test_fn_f_inv_rt_sanity() {
+    let mut model = new_empty_model();
+
+    // Valid call: left-tail inverse
+    model._set("A1", "=F.INV.RT(0.0102580476059808, 6, 4)");
+
+    // Too many args
+    model._set("A2", "=F.INV.RT(0.5, 6, 4, 2)");
+
+    // Too few args
+    model._set("A3", "=F.INV.RT(0.5, 6)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"15");
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+}

base/src/test/statistical/test_fn_f_test.rs

@@ -0,0 +1,35 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_f_test_sanity() {
+    let mut model = new_empty_model();
+
+    // Valid call
+    model._set("A1", "=F.TEST(A2:A7, B2:B7)");
+    model._set("A2", "9");
+    model._set("A3", "12");
+    model._set("A4", "14");
+    model._set("A5", "16");
+    model._set("A6", "18");
+    model._set("A7", "20");
+    model._set("B2", "11");
+    model._set("B3", "10");
+    model._set("B4", "15");
+    model._set("B5", "17");
+    model._set("B6", "19");
+    model._set("B7", "21");
+
+    // Too few args
+    model._set("A8", "=F.TEST(A2:A7)");
+
+    // Too many args
+    model._set("A9", "=F.TEST(A2:A7, B2:B7, C2:C7)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.859284302");
+    assert_eq!(model._get_text("A8"), *"#ERROR!");
+    assert_eq!(model._get_text("A9"), *"#ERROR!");
+}

base/src/test/statistical/test_fn_fisher.rs

@@ -0,0 +1,53 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+#[test]
+fn test_fn_fisher_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid inputs
+    model._set("A1", "=FISHER(0.1)");
+    model._set("A2", "=FISHER(-0.5)");
+    model._set("A3", "=FISHER(0.8)");
+
+    // Domain errors: x <= -1 or x >= 1 -> #NUM!
+    model._set("A4", "=FISHER(1)");
+    model._set("A5", "=FISHER(-1)");
+    model._set("A6", "=FISHER(2)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A7", "=FISHER(0.1, 2)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.100335348");
+    assert_eq!(model._get_text("A2"), *"-0.549306144");
+    assert_eq!(model._get_text("A3"), *"1.098612289");
+
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+
+    assert_eq!(model._get_text("A7"), *"#ERROR!");
+}
+
+#[test]
+fn test_fn_fisher_inv_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid inputs
+    model._set("A1", "=FISHERINV(-1.5)");
+    model._set("A2", "=FISHERINV(0.5)");
+    model._set("A3", "=FISHERINV(2)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A4", "=FISHERINV(0.5, 1)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"-0.905148254");
+    assert_eq!(model._get_text("A2"), *"0.462117157");
+    assert_eq!(model._get_text("A3"), *"0.96402758");
+
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+}

base/src/test/statistical/test_fn_gauss.rs

@@ -0,0 +1,35 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_gauss_smoke() {
+    let mut model = new_empty_model();
+    model._set("A1", "=GAUSS(-3)");
+    model._set("A2", "=GAUSS(-2.3)");
+    model._set("A3", "=GAUSS(-1.7)");
+    model._set("A4", "=GAUSS(0)");
+    model._set("A5", "=GAUSS(0.5)");
+    model._set("A6", "=GAUSS(1)");
+    model._set("A7", "=GAUSS(1.3)");
+    model._set("A8", "=GAUSS(3)");
+    model._set("A9", "=GAUSS(4)");
+
+    model._set("G6", "=GAUSS()");
+    model._set("G7", "=GAUSS(1, 1)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"-0.498650102");
+    assert_eq!(model._get_text("A2"), *"-0.48927589");
+    assert_eq!(model._get_text("A3"), *"-0.455434537");
+    assert_eq!(model._get_text("A4"), *"0");
+    assert_eq!(model._get_text("A5"), *"0.191462461");
+    assert_eq!(model._get_text("A6"), *"0.341344746");
+    assert_eq!(model._get_text("A7"), *"0.403199515");
+    assert_eq!(model._get_text("A8"), *"0.498650102");
+    assert_eq!(model._get_text("A9"), *"0.499968329");
+
+    assert_eq!(model._get_text("G6"), *"#ERROR!");
+    assert_eq!(model._get_text("G7"), *"#ERROR!");
+}

base/src/test/statistical/test_fn_hyp_geom_dist.rs

@@ -0,0 +1,42 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_hyp_geom_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: PDF (non-cumulative)
+    model._set("A1", "=HYPGEOM.DIST(1, 4, 12, 20, FALSE)");
+
+    // Valid: CDF (cumulative)
+    model._set("A2", "=HYPGEOM.DIST(1, 4, 12, 20, TRUE)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A3", "=HYPGEOM.DIST(1, 4, 12, 20)");
+    model._set("A4", "=HYPGEOM.DIST(1, 4, 12, 20, TRUE, FALSE)");
+
+    // Domain errors:
+    // sample_s > number_sample -> #NUM!
+    model._set("A5", "=HYPGEOM.DIST(5, 4, 12, 20, TRUE)");
+
+    // population_s > number_pop -> #NUM!
+    model._set("A6", "=HYPGEOM.DIST(1, 4, 25, 20, TRUE)");
+
+    // number_sample > number_pop -> #NUM!
+    model._set("A7", "=HYPGEOM.DIST(1, 25, 12, 20, TRUE)");
+
+    model.evaluate();
+
+    // PDF: P(X = 1)
+    assert_eq!(model._get_text("A1"), *"0.13869969");
+
+    // CDF: P(X <= 1)
+    assert_eq!(model._get_text("A2"), *"0.153147575");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+}

base/src/test/statistical/test_fn_log_norm.rs

@@ -0,0 +1,61 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_log_norm_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: CDF and PDF
+    model._set("A1", "=LOGNORM.DIST(4, 3.5, 1.2, TRUE)");
+    model._set("A2", "=LOGNORM.DIST(4, 3.5, 1.2, FALSE)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A3", "=LOGNORM.DIST(4, 3.5, 1.2)");
+    model._set("A4", "=LOGNORM.DIST(4, 3.5, 1.2, TRUE, FALSE)");
+
+    // Domain errors:
+    // x <= 0 -> #NUM!
+    model._set("A5", "=LOGNORM.DIST(0, 3.5, 1.2, TRUE)");
+    // std_dev <= 0 -> #NUM!
+    model._set("A6", "=LOGNORM.DIST(4, 3.5, 0, TRUE)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.039083556");
+    assert_eq!(model._get_text("A2"), *"0.017617597");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_log_norm_inv_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid call
+    model._set("A1", "=LOGNORM.INV(0.5, 3.5, 1.2)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A2", "=LOGNORM.INV(0.5, 3.5)");
+    model._set("A3", "=LOGNORM.INV(0.5, 3.5, 1.2, 0)");
+
+    // Domain errors:
+    // probability <= 0 or >= 1 -> #NUM!
+    model._set("A4", "=LOGNORM.INV(0, 3.5, 1.2)");
+    model._set("A5", "=LOGNORM.INV(1, 3.5, 1.2)");
+    // std_dev <= 0 -> #NUM!
+    model._set("A6", "=LOGNORM.INV(0.5, 3.5, 0)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"33.115451959");
+
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}

base/src/test/statistical/test_fn_norm_dist.rs

@@ -0,0 +1,119 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_norm_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: standard normal as a special case
+    model._set("A1", "=NORM.DIST(1, 0, 1, TRUE)");
+    model._set("A2", "=NORM.DIST(1, 0, 1, FALSE)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A3", "=NORM.DIST(1, 0, 1)");
+    model._set("A4", "=NORM.DIST(1, 0, 1, TRUE, FALSE)");
+
+    // Domain errors: standard_dev <= 0 -> #NUM!
+    model._set("A5", "=NORM.DIST(1, 0, 0, TRUE)");
+    model._set("A6", "=NORM.DIST(1, 0, -1, TRUE)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.841344746");
+    assert_eq!(model._get_text("A2"), *"0.241970725");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_norm_inv_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: median of standard normal
+    model._set("A1", "=NORM.INV(0.5, 0, 1)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A2", "=NORM.INV(0.5, 0)");
+    model._set("A3", "=NORM.INV(0.5, 0, 1, 0)");
+
+    // Domain errors:
+    // probability <= 0 or >= 1 -> #NUM!
+    model._set("A4", "=NORM.INV(0, 0, 1)");
+    model._set("A5", "=NORM.INV(1, 0, 1)");
+    // standard_dev <= 0 -> #NUM!
+    model._set("A6", "=NORM.INV(0.5, 0, 0)");
+
+    model._set("A7", "=NORM.INV(0.7, 0.2, 1)");
+    model._set("A8", "=NORM.INV(0.7, 0.2, 5)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0");
+
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"0.724400513");
+    assert_eq!(model._get_text("A8"), *"2.822002564");
+}
+
+#[test]
+fn test_fn_norm_s_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: CDF and PDF at z = 0
+    model._set("A1", "=NORM.S.DIST(0, TRUE)");
+    model._set("A2", "=NORM.S.DIST(0, FALSE)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A3", "=NORM.S.DIST(0)");
+    model._set("A4", "=NORM.S.DIST(0, TRUE, FALSE)");
+
+    model._set("A5", "=NORM.S.DIST(0.2, FALSE)");
+    model._set("A6", "=NORM.S.DIST(2.2, TRUE)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.5");
+    assert_eq!(model._get_text("A2"), *"0.39894228");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+
+    assert_eq!(model._get_text("A5"), *"0.391042694");
+    assert_eq!(model._get_text("A6"), *"0.986096552");
+}
+
+#[test]
+fn test_fn_norm_s_inv_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: symmetric points
+    model._set("A1", "=NORM.S.INV(0.5)");
+    model._set("A2", "=NORM.S.INV(0.841344746)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A3", "=NORM.S.INV()");
+    model._set("A4", "=NORM.S.INV(0.5, 0)");
+
+    // Domain errors: probability <= 0 or >= 1 -> #NUM!
+    model._set("A5", "=NORM.S.INV(0)");
+    model._set("A6", "=NORM.S.INV(1)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0");
+    // Approximately 1
+    assert_eq!(model._get_text("A2"), *"1");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}

base/src/test/statistical/test_fn_pearson.rs

@@ -0,0 +1,31 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_chisq_test_smoke() {
+    let mut model = new_empty_model();
+    model._set("A2", "48");
+    model._set("A3", "32");
+    model._set("A4", "12");
+    model._set("A5", "1");
+    model._set("A6", "'13");
+    model._set("A7", "TRUE");
+    model._set("A8", "1");
+    model._set("A9", "13");
+    model._set("A10", "15");
+
+    model._set("B2", "55");
+    model._set("B3", "34");
+    model._set("B4", "13");
+    model._set("B5", "blah");
+    model._set("B6", "13");
+    model._set("B7", "1");
+    model._set("B8", "TRUE");
+    model._set("B9", "'14");
+    model._set("B10", "16");
+
+    model._set("C1", "=PEARSON(A2:A10, B2:B10)");
+    model.evaluate();
+    assert_eq!(model._get_text("C1"), *"0.998381439");
+}

base/src/test/statistical/test_fn_phi.rs

@@ -0,0 +1,26 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_phi_smoke() {
+    let mut model = new_empty_model();
+
+    model._set("A1", "=PHI(0)");
+    model._set("A2", "=PHI(1)");
+    model._set("A3", "=PHI(-1)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A4", "=PHI()");
+    model._set("A5", "=PHI(0, 1)");
+
+    model.evaluate();
+
+    // Standard values
+    assert_eq!(model._get_text("A1"), *"0.39894228");
+    assert_eq!(model._get_text("A2"), *"0.241970725");
+    assert_eq!(model._get_text("A3"), *"0.241970725");
+
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#ERROR!");
+}

base/src/test/statistical/test_fn_poisson.rs

@@ -0,0 +1,41 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_poisson_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // λ = 2, x = 3
+    // P(X = 3)  ≈ 0.180447045
+    // P(X <= 3) ≈ 0.857123461
+    model._set("A1", "=POISSON.DIST(3, 2, FALSE)");
+    model._set("A2", "=POISSON.DIST(3, 2, TRUE)");
+
+    // Wrong arg count
+    model._set("A3", "=POISSON.DIST(3, 2)");
+    model._set("A4", "=POISSON.DIST(3, 2, TRUE, FALSE)");
+
+    // Domain errors
+    model._set("A5", "=POISSON.DIST(-1, 2, TRUE)"); // x < 0
+    model._set("A6", "=POISSON.DIST(3, -2, TRUE)"); // mean < 0
+
+    // λ = 0 special cases
+    model._set("A7", "=POISSON.DIST(0, 0, FALSE)"); // 1
+    model._set("A8", "=POISSON.DIST(1, 0, FALSE)"); // 0
+    model._set("A9", "=POISSON.DIST(5, 0, TRUE)"); // 1
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.180447044");
+    assert_eq!(model._get_text("A2"), *"0.85712346");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+
+    assert_eq!(model._get_text("A7"), *"1");
+    assert_eq!(model._get_text("A8"), *"0");
+    assert_eq!(model._get_text("A9"), *"1");
+}

base/src/test/statistical/test_fn_stdev.rs

@@ -0,0 +1,46 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn smoke_test() {
+    let mut model = new_empty_model();
+    model._set("A1", "=STDEV.P(10, 12, 23, 23, 16, 23, 21)");
+    model._set("A2", "=STDEV.S(10, 12, 23, 23, 16, 23, 21)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"5.174505793");
+
+    assert_eq!(model._get_text("A2"), *"5.589105048");
+}
+
+#[test]
+fn numbers() {
+    let mut model = new_empty_model();
+
+    model._set("A2", "24");
+    model._set("A3", "25");
+    model._set("A4", "27");
+    model._set("A5", "23");
+    model._set("A6", "45");
+    model._set("A7", "23.5");
+    model._set("A8", "34");
+    model._set("A9", "23");
+    model._set("A10", "23");
+    model._set("A11", "TRUE");
+    model._set("A12", "'23");
+    model._set("A13", "Text");
+    model._set("A14", "FALSE");
+    model._set("A15", "45");
+
+    model._set("B1", "=STDEV.P(A2:A15)");
+    model._set("B2", "=STDEV.S(A2:A15)");
+    model._set("B3", "=STDEVA(A2:A15)");
+    model._set("B4", "=STDEVPA(A2:A15)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("B1"), *"8.483071378");
+    assert_eq!(model._get_text("B2"), *"8.941942369");
+    assert_eq!(model._get_text("B3"), *"15.499955689");
+    assert_eq!(model._get_text("B4"), *"14.936131032");
+}

base/src/test/statistical/test_fn_t_dist.rs

@@ -0,0 +1,160 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_t_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: cumulative (left-tail CDF)
+    model._set("A1", "=T.DIST(2, 10, TRUE)");
+    // Valid: probability density function (PDF)
+    model._set("B1", "=T.DIST(2, 10, FALSE)");
+
+    // Wrong number of arguments
+    model._set("A2", "=T.DIST(2, 10)");
+    model._set("A3", "=T.DIST(2, 10, TRUE, FALSE)");
+
+    // Domain error: df < 1 -> #NUM!
+    model._set("A4", "=T.DIST(2, 0, TRUE)");
+    model._set("A5", "=T.DIST(2, -1, TRUE)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.963305983");
+    assert_eq!(model._get_text("B1"), *"0.061145766");
+
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_t_dist_rt_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: right tail probability
+    model._set("A1", "=T.DIST.RT(2, 10)");
+
+    // Wrong number of arguments
+    model._set("A2", "=T.DIST.RT(2)");
+    model._set("A3", "=T.DIST.RT(2, 10, TRUE)");
+
+    // Domain error: df < 1
+    model._set("A4", "=T.DIST.RT(2, 0)");
+    model._set("A5", "=T.DIST.RT(2, -1)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.036694017");
+
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#NUM!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_t_dist_2t_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: two-tailed probability
+    model._set("A1", "=T.DIST.2T(2, 10)");
+
+    // In the limit case of x = 0, the two-tailed probability is 1.0
+    model._set("A4", "=T.DIST.2T(0, 10)");
+
+    // Wrong number of arguments
+    model._set("A2", "=T.DIST.2T(2)");
+    model._set("A3", "=T.DIST.2T(2, 10, TRUE)");
+
+    // Domain errors:
+    // x < 0 -> #NUM!
+    model._set("A5", "=T.DIST.2T(-0.001, 10)");
+    // df < 1 -> #NUM!
+    model._set("A6", "=T.DIST.2T(2, 0)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0.073388035");
+    assert_eq!(model._get_text("A4"), *"1");
+
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_t_inv_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: upper and lower tail
+    model._set("A1", "=T.INV(0.95, 10)");
+    model._set("A2", "=T.INV(0.05, 10)");
+    // limit case:
+    model._set("B2", "=T.INV(0.95, 1)");
+
+    // Wrong number of arguments
+    model._set("A3", "=T.INV(0.95)");
+    model._set("A4", "=T.INV(0.95, 10, 1)");
+
+    // Domain errors:
+    // p <= 0 or >= 1
+    model._set("A5", "=T.INV(0, 10)");
+    model._set("A6", "=T.INV(1, 10)");
+    // df < 1
+    model._set("A7", "=T.INV(0.95, 0)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"1.812461123");
+    assert_eq!(model._get_text("A2"), *"-1.812461123");
+    assert_eq!(model._get_text("B2"), *"6.313751515");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+}
+
+#[test]
+fn test_fn_t_inv_2t_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: two-tailed critical values
+    model._set("A1", "=T.INV.2T(0.1, 10)");
+    model._set("A2", "=T.INV.2T(0.05, 10)");
+
+    // p = 1 should give t = 0 (both tails outside are 1.0, so cut at the mean)
+    model._set("A3", "=T.INV.2T(1, 10)");
+
+    model._set("A7", "=T.INV.2T(1.5, 10)");
+
+    // Wrong number of arguments
+    model._set("A4", "=T.INV.2T(0.1)");
+    model._set("A5", "=T.INV.2T(0.1, 10, 1)");
+
+    // Domain errors:
+    // p <= 0 or p > 1
+    model._set("A6", "=T.INV.2T(0, 10)");
+    // df < 1
+    model._set("A8", "=T.INV.2T(0.1, 0)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"1.812461123");
+    assert_eq!(model._get_text("A2"), *"2.228138852");
+    assert_eq!(model._get_text("A3"), *"0");
+
+    // NB: Excel returns -0.699812061 for T.INV.2T(1.5, 10)
+    // which seems inconsistent with its documented behavior
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#ERROR!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A8"), *"#NUM!");
+}

base/src/test/statistical/test_fn_t_test.rs

@@ -0,0 +1,41 @@
+#![allow(clippy::unwrap_used)]
+use crate::test::util::new_empty_model;
+#[test]
+fn test_fn_t_test_smoke() {
+    let mut model = new_empty_model();
+    model._set("A2", "3");
+    model._set("A3", "4");
+    model._set("A4", "5");
+    model._set("A5", "6");
+    model._set("A6", "10");
+    model._set("A7", "3");
+    model._set("A8", "2");
+    model._set("A9", "4");
+    model._set("A10", "7");
+
+    model._set("B2", "6");
+    model._set("B3", "19");
+    model._set("B4", "3");
+    model._set("B5", "2");
+    model._set("B6", "13");
+    model._set("B7", "4");
+    model._set("B8", "5");
+    model._set("B9", "17");
+    model._set("B10", "3");
+
+    model._set("C1", "=T.TEST(A2:A10, B2:B10, 1, 1)");
+    model._set("C2", "=T.TEST(A2:A10, B2:B10, 1, 2)");
+    model._set("C3", "=T.TEST(A2:A10, B2:B10, 1, 3)");
+    model._set("C4", "=T.TEST(A2:A10, B2:B10, 2, 1)");
+    model._set("C5", "=T.TEST(A2:A10, B2:B10, 2, 2)");
+    model._set("C6", "=T.TEST(A2:A10, B2:B10, 2, 3)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("C1"), *"0.103836888");
+    assert_eq!(model._get_text("C2"), *"0.100244599");
+    assert_eq!(model._get_text("C3"), *"0.105360319");
+    assert_eq!(model._get_text("C4"), *"0.207673777");
+    assert_eq!(model._get_text("C5"), *"0.200489197");
+    assert_eq!(model._get_text("C6"), *"0.210720639");
+}

base/src/test/statistical/test_fn_var.rs

@@ -0,0 +1,46 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn smoke_test() {
+    let mut model = new_empty_model();
+    model._set("A1", "=STDEV.P(10, 12, 23, 23, 16, 23, 21)");
+    model._set("A2", "=STDEV.S(10, 12, 23, 23, 16, 23, 21)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"5.174505793");
+
+    assert_eq!(model._get_text("A2"), *"5.589105048");
+}
+
+#[test]
+fn numbers() {
+    let mut model = new_empty_model();
+
+    model._set("A2", "24");
+    model._set("A3", "25");
+    model._set("A4", "27");
+    model._set("A5", "23");
+    model._set("A6", "45");
+    model._set("A7", "23.5");
+    model._set("A8", "34");
+    model._set("A9", "23");
+    model._set("A10", "23");
+    model._set("A11", "TRUE");
+    model._set("A12", "'23");
+    model._set("A13", "Text");
+    model._set("A14", "FALSE");
+    model._set("A15", "45");
+
+    model._set("B1", "=VAR.P(A2:A15)");
+    model._set("B2", "=VAR.S(A2:A15)");
+    model._set("B3", "=VARA(A2:A15)");
+    model._set("B4", "=VARPA(A2:A15)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("B1"), *"71.9625");
+    assert_eq!(model._get_text("B2"), *"79.958333333");
+    assert_eq!(model._get_text("B3"), *"240.248626374");
+    assert_eq!(model._get_text("B4"), *"223.088010204");
+}

base/src/test/statistical/test_fn_weibull.rs

@@ -0,0 +1,41 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_weibull_dist_smoke() {
+    let mut model = new_empty_model();
+
+    // Valid: CDF and PDF for x = 1, alpha = 2, beta = 1
+    model._set("A1", "=WEIBULL.DIST(1, 2, 1, TRUE)");
+    model._set("A2", "=WEIBULL.DIST(1, 2, 1, FALSE)");
+
+    // Wrong number of arguments -> #ERROR!
+    model._set("A3", "=WEIBULL.DIST(1, 2, 1)");
+    model._set("A4", "=WEIBULL.DIST(1, 2, 1, TRUE, FALSE)");
+
+    // Domain errors:
+    // x < 0  -> #NUM!
+    model._set("A5", "=WEIBULL.DIST(-1, 2, 1, TRUE)");
+    // alpha <= 0 -> #NUM!
+    model._set("A6", "=WEIBULL.DIST(1, 0, 1, TRUE)");
+    model._set("A7", "=WEIBULL.DIST(1, -1, 1, TRUE)");
+    // beta <= 0 -> #NUM!
+    model._set("A8", "=WEIBULL.DIST(1, 2, 0, TRUE)");
+    model._set("A9", "=WEIBULL.DIST(1, 2, -1, TRUE)");
+
+    model.evaluate();
+
+    // 1 - e^-1
+    assert_eq!(model._get_text("A1"), *"0.632120559");
+    // 2 * e^-1
+    assert_eq!(model._get_text("A2"), *"0.735758882");
+
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#NUM!");
+    assert_eq!(model._get_text("A6"), *"#NUM!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+    assert_eq!(model._get_text("A8"), *"#NUM!");
+    assert_eq!(model._get_text("A9"), *"#NUM!");
+}

base/src/test/statistical/test_fn_z_test.rs

@@ -0,0 +1,36 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_fn_z_test_smoke() {
+    let mut model = new_empty_model();
+    model._set("A2", "3");
+    model._set("A3", "6");
+    model._set("A4", "7");
+    model._set("A5", "8");
+    model._set("A6", "6");
+    model._set("A7", "5");
+    model._set("A8", "4");
+    model._set("A9", "2");
+    model._set("A10", "1");
+    model._set("A11", "9");
+
+    model._set("G1", "=Z.TEST(A2:A11, 4)");
+    model._set("G2", "=Z.TEST(A2:A11, 6)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("G1"), *"0.090574197");
+    assert_eq!(model._get_text("G2"), *"0.863043389");
+}
+
+#[test]
+fn arrays() {
+    let mut model = new_empty_model();
+    model._set("D1", "=Z.TEST({5,2,3,4}, 4, 123)");
+    model._set("D2", "=Z.TEST({5,2,3,4}, 4)");
+    model.evaluate();
+
+    assert_eq!(model._get_text("D1"), *"0.503243397");
+    assert_eq!(model._get_text("D2"), *"0.780710987");
+}

base/src/test/test_arabic_roman

@@ -0,0 +1,27 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn arguments() {
+    let mut model = new_empty_model();
+    model._set("A1", "=ARABIC()");
+    model._set("A2", "=ARABIC(V)");
+    model._set("A3", "=ARABIC(V, 2)");
+
+    model._set("A4", "=ROMAN()");
+    model._set("A5", "=ROMAN(5)");
+    model._set("A6", "=ROMAN(5, 0)");
+    model._set("A7", "=ROMAN(5, 0, 2)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"#ERROR!");
+    assert_eq!(model._get_text("A2"), *"5");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"V");
+    assert_eq!(model._get_text("A6"), *"V");
+    assert_eq!(model._get_text("A7"), *"#ERROR!");
+}

base/src/test/test_cell_info_n_sheets

@@ -0,0 +1,35 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn arguments() {
+    let mut model = new_empty_model();
+    model._set("A1", "=CELL("address",A1)");
+    model._set("A2", "=CELL()");
+
+    model._set("A3", "=INFO("system")");
+    model._set("A4", "=INFO()");
+
+    model._set("A5", "=N(TRUE)");
+    model._set("A6", "=N()");
+    model._set("A7", "=N(1, 2)");
+
+    model._set("A8", "=SHEETS()");
+    model._set("A9", "=SHEETS(1)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"$A$1");
+    assert_eq!(model._get_text("A2"), *"#ERROR!");
+
+    assert_eq!(model._get_text("A3"), *"#N/IMPL!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+
+    assert_eq!(model._get_text("A5"), *"1");
+    assert_eq!(model._get_text("A6"), *"#ERROR!");
+    assert_eq!(model._get_text("A7"), *"#ERROR!");
+
+    assert_eq!(model._get_text("A8"), *"1");
+    assert_eq!(model._get_text("A9"), *"#N/IMPL!");
+}

base/src/test/test_combin_combina.rs

@@ -0,0 +1,27 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn arguments() {
+    let mut model = new_empty_model();
+    model._set("A1", "=COMBIN(5,2)");
+    model._set("A2", "=COMBINA(5,2)");
+    model._set("A3", "=COMBIN()");
+    model._set("A4", "=COMBINA()");
+    model._set("A5", "=COMBIN(2)");
+    model._set("A6", "=COMBINA(2)");
+    model._set("A7", "=COMBIN(1, 2, 3)");
+    model._set("A8", "=COMBINA(1, 2, 3)");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"10");
+    assert_eq!(model._get_text("A2"), *"15");
+    assert_eq!(model._get_text("A3"), *"#ERROR!");
+    assert_eq!(model._get_text("A4"), *"#ERROR!");
+    assert_eq!(model._get_text("A5"), *"#ERROR!");
+    assert_eq!(model._get_text("A6"), *"#ERROR!");
+    assert_eq!(model._get_text("A7"), *"#ERROR!");
+    assert_eq!(model._get_text("A8"), *"#ERROR!");
+}

base/src/test/test_date_and_time.rs

@@ -6,6 +6,11 @@
 /// We can also enter examples that illustrate/document a part of the function
 use crate::{cell::CellValue, test::util::new_empty_model};
 
+// Excel uses a serial date system where Jan 1, 1900 = 1 (though it treats 1900 as a leap year)
+// Most test dates are documented inline, but we define boundary values here:
+const EXCEL_MAX_DATE: f64 = 2958465.0; // Dec 31, 9999 - used in boundary tests
+const EXCEL_INVALID_DATE: f64 = 2958466.0; // One day past max - used in error tests
+
 #[test]
 fn test_fn_date_arguments() {
     let mut model = new_empty_model();
@@ -216,3 +221,380 @@ fn test_date_early_dates() {
         Ok(CellValue::Number(61.0))
     );
 }
+#[test]
+fn test_days_function() {
+    let mut model = new_empty_model();
+
+    // Basic functionality
+    model._set("A1", "=DAYS(44570,44561)");
+    model._set("A2", "=DAYS(44561,44570)"); // Reversed order
+    model._set("A3", "=DAYS(44561,44561)");
+
+    // Edge cases
+    model._set("A4", "=DAYS(1,2)"); // Early dates
+    model._set(
+        "A5",
+        &format!("=DAYS({},{})", EXCEL_MAX_DATE, EXCEL_MAX_DATE - 1.0),
+    ); // Near max date
+
+    // Error cases - wrong argument count
+    model._set("A6", "=DAYS()");
+    model._set("A7", "=DAYS(44561)");
+    model._set("A8", "=DAYS(44561,44570,1)");
+
+    // Error cases - invalid dates
+    model._set("A9", "=DAYS(-1,44561)");
+    model._set("A10", &format!("=DAYS(44561,{EXCEL_INVALID_DATE})"));
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"9");
+    assert_eq!(model._get_text("A2"), *"-9");
+    assert_eq!(model._get_text("A3"), *"0");
+    assert_eq!(model._get_text("A4"), *"-1"); // DAYS(1,2) = 1-2 = -1
+    assert_eq!(model._get_text("A5"), *"1");
+    assert_eq!(model._get_text("A6"), *"#ERROR!");
+    assert_eq!(model._get_text("A7"), *"#ERROR!");
+    assert_eq!(model._get_text("A8"), *"#ERROR!");
+    assert_eq!(model._get_text("A9"), *"#NUM!");
+    assert_eq!(model._get_text("A10"), *"#NUM!");
+}
+
+#[test]
+fn test_days360_function() {
+    let mut model = new_empty_model();
+
+    // Basic functionality with different basis values
+    model._set("A1", "=DAYS360(44196,44560)"); // Default basis (US 30/360)
+    model._set("A2", "=DAYS360(44196,44560,FALSE)"); // US 30/360 explicitly
+    model._set("A3", "=DAYS360(44196,44560,TRUE)"); // European 30/360
+
+    // Same date
+    model._set("A4", "=DAYS360(44561,44561)");
+    model._set("A5", "=DAYS360(44561,44561,TRUE)");
+
+    // Reverse order (negative result)
+    model._set("A6", "=DAYS360(44560,44196)");
+    model._set("A7", "=DAYS360(44560,44196,TRUE)");
+
+    // Edge cases
+    model._set("A8", "=DAYS360(1,2)");
+    model._set("A9", "=DAYS360(1,2,FALSE)");
+
+    // Error cases - wrong argument count
+    model._set("A10", "=DAYS360()");
+    model._set("A11", "=DAYS360(44561)");
+    model._set("A12", "=DAYS360(44561,44570,TRUE,1)");
+
+    // Error cases - invalid dates
+    model._set("A13", "=DAYS360(-1,44561)");
+    model._set("A14", &format!("=DAYS360(44561,{EXCEL_INVALID_DATE})"));
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"360");
+    assert_eq!(model._get_text("A2"), *"360");
+    assert_eq!(model._get_text("A3"), *"360");
+    assert_eq!(model._get_text("A4"), *"0");
+    assert_eq!(model._get_text("A5"), *"0");
+    assert_eq!(model._get_text("A6"), *"-360");
+    assert_eq!(model._get_text("A7"), *"-360");
+    assert_eq!(model._get_text("A8"), *"1");
+    assert_eq!(model._get_text("A9"), *"1");
+    assert_eq!(model._get_text("A10"), *"#ERROR!");
+    assert_eq!(model._get_text("A11"), *"#ERROR!");
+    assert_eq!(model._get_text("A12"), *"#ERROR!");
+    assert_eq!(model._get_text("A13"), *"#NUM!");
+    assert_eq!(model._get_text("A14"), *"#NUM!");
+}
+
+#[test]
+fn test_weekday_function() {
+    let mut model = new_empty_model();
+
+    // Test return_type parameter variations with one known date (Friday 44561)
+    model._set("A1", "=WEEKDAY(44561)"); // Default: Sun=1, Fri=6
+    model._set("A2", "=WEEKDAY(44561,2)"); // Mon=1, Fri=5
+    model._set("A3", "=WEEKDAY(44561,3)"); // Mon=0, Fri=4
+
+    // Test boundary days (Sun/Mon) to verify return_type logic
+    model._set("A4", "=WEEKDAY(44556,1)"); // Sunday: should be 1
+    model._set("A5", "=WEEKDAY(44556,2)"); // Sunday: should be 7
+    model._set("A6", "=WEEKDAY(44557,2)"); // Monday: should be 1
+
+    // Error cases
+    model._set("A7", "=WEEKDAY()"); // Wrong arg count
+    model._set("A8", "=WEEKDAY(44561,0)"); // Invalid return_type
+    model._set("A9", "=WEEKDAY(-1)"); // Invalid date
+
+    model.evaluate();
+
+    // Core functionality
+    assert_eq!(model._get_text("A1"), *"6"); // Friday default
+    assert_eq!(model._get_text("A2"), *"5"); // Friday Mon=1
+    assert_eq!(model._get_text("A3"), *"4"); // Friday Mon=0
+
+    // Boundary verification
+    assert_eq!(model._get_text("A4"), *"1"); // Sunday Sun=1
+    assert_eq!(model._get_text("A5"), *"7"); // Sunday Mon=1
+    assert_eq!(model._get_text("A6"), *"1"); // Monday Mon=1
+
+    // Error cases
+    assert_eq!(model._get_text("A7"), *"#ERROR!");
+    assert_eq!(model._get_text("A8"), *"#VALUE!");
+    assert_eq!(model._get_text("A9"), *"#NUM!");
+}
+
+#[test]
+fn test_weeknum_function() {
+    let mut model = new_empty_model();
+
+    // Test different return_type values (1=week starts Sunday, 2=week starts Monday)
+    model._set("A1", "=WEEKNUM(44561)"); // Default return_type=1
+    model._set("A2", "=WEEKNUM(44561,1)"); // Sunday start
+    model._set("A3", "=WEEKNUM(44561,2)"); // Monday start
+
+    // Test year boundaries
+    model._set("A4", "=WEEKNUM(43831,1)"); // Jan 1, 2020 (Wednesday)
+    model._set("A5", "=WEEKNUM(43831,2)"); // Jan 1, 2020 (Wednesday)
+    model._set("A6", "=WEEKNUM(44196,1)"); // Dec 31, 2020 (Thursday)
+    model._set("A7", "=WEEKNUM(44196,2)"); // Dec 31, 2020 (Thursday)
+
+    // Test first and last weeks of year
+    model._set("A8", "=WEEKNUM(44197,1)"); // Jan 1, 2021 (Friday)
+    model._set("A9", "=WEEKNUM(44197,2)"); // Jan 1, 2021 (Friday)
+    model._set("A10", "=WEEKNUM(44561,1)"); // Dec 31, 2021 (Friday)
+    model._set("A11", "=WEEKNUM(44561,2)"); // Dec 31, 2021 (Friday)
+
+    // Error cases - wrong argument count
+    model._set("A12", "=WEEKNUM()");
+    model._set("A13", "=WEEKNUM(44561,1,1)");
+
+    // Error cases - invalid return_type
+    model._set("A14", "=WEEKNUM(44561,0)");
+    model._set("A15", "=WEEKNUM(44561,3)");
+    model._set("A16", "=WEEKNUM(44561,-1)");
+
+    // Error cases - invalid dates
+    model._set("A17", "=WEEKNUM(-1)");
+    model._set("A18", &format!("=WEEKNUM({EXCEL_INVALID_DATE})"));
+
+    model.evaluate();
+
+    // Basic functionality
+    assert_eq!(model._get_text("A1"), *"53"); // Week 53
+    assert_eq!(model._get_text("A2"), *"53"); // Week 53 (Sunday start)
+    assert_eq!(model._get_text("A3"), *"53"); // Week 53 (Monday start)
+
+    // Year boundary tests
+    assert_eq!(model._get_text("A4"), *"1"); // Jan 1, 2020 (Sunday start)
+    assert_eq!(model._get_text("A5"), *"1"); // Jan 1, 2020 (Monday start)
+    assert_eq!(model._get_text("A6"), *"53"); // Dec 31, 2020 (Sunday start)
+    assert_eq!(model._get_text("A7"), *"53"); // Dec 31, 2020 (Monday start)
+
+    // 2021 tests
+    assert_eq!(model._get_text("A8"), *"1"); // Jan 1, 2021 (Sunday start)
+    assert_eq!(model._get_text("A9"), *"1"); // Jan 1, 2021 (Monday start)
+    assert_eq!(model._get_text("A10"), *"53"); // Dec 31, 2021 (Sunday start)
+    assert_eq!(model._get_text("A11"), *"53"); // Dec 31, 2021 (Monday start)
+
+    // Error cases
+    assert_eq!(model._get_text("A12"), *"#ERROR!");
+    assert_eq!(model._get_text("A13"), *"#ERROR!");
+    assert_eq!(model._get_text("A14"), *"#VALUE!");
+    assert_eq!(model._get_text("A15"), *"#VALUE!");
+    assert_eq!(model._get_text("A16"), *"#VALUE!");
+    assert_eq!(model._get_text("A17"), *"#NUM!");
+    assert_eq!(model._get_text("A18"), *"#NUM!");
+}
+
+#[test]
+fn test_workday_function() {
+    let mut model = new_empty_model();
+
+    // Basic functionality
+    model._set("A1", "=WORKDAY(44560,1)");
+    model._set("A2", "=WORKDAY(44561,-1)");
+    model._set("A3", "=WORKDAY(44561,0)");
+    model._set("A4", "=WORKDAY(44560,5)");
+
+    // Test with holidays
+    model._set("B1", "44561");
+    model._set("A5", "=WORKDAY(44560,1,B1)"); // Should skip the holiday
+    model._set("B2", "44562");
+    model._set("B3", "44563");
+    model._set("A6", "=WORKDAY(44560,3,B1:B3)"); // Multiple holidays
+
+    // Test starting on weekend
+    model._set("A7", "=WORKDAY(44562,1)"); // Saturday start
+    model._set("A8", "=WORKDAY(44563,1)"); // Sunday start
+
+    // Test negative workdays
+    model._set("A9", "=WORKDAY(44565,-3)"); // Go backwards 3 days
+    model._set("A10", "=WORKDAY(44565,-5,B1:B3)"); // Backwards with holidays
+
+    // Edge cases
+    model._set("A11", "=WORKDAY(1,1)"); // Early date
+    model._set("A12", "=WORKDAY(100000,10)"); // Large numbers
+
+    // Error cases - wrong argument count
+    model._set("A13", "=WORKDAY()");
+    model._set("A14", "=WORKDAY(44560)");
+    model._set("A15", "=WORKDAY(44560,1,B1,B2)");
+
+    // Error cases - invalid dates
+    model._set("A16", "=WORKDAY(-1,1)");
+    model._set("A17", &format!("=WORKDAY({EXCEL_INVALID_DATE},1)"));
+
+    // Error cases - invalid holiday dates
+    model._set("B4", "-1");
+    model._set("A18", "=WORKDAY(44560,1,B4)");
+
+    model.evaluate();
+
+    // Basic functionality
+    assert_eq!(model._get_text("A1"), *"44561"); // 1 day forward
+    assert_eq!(model._get_text("A2"), *"44560"); // 1 day backward
+    assert_eq!(model._get_text("A3"), *"44561"); // 0 days
+    assert_eq!(model._get_text("A4"), *"44567"); // 5 days forward
+
+    // With holidays
+    assert_eq!(model._get_text("A5"), *"44564"); // Skip holiday, go to Monday
+    assert_eq!(model._get_text("A6"), *"44566"); // Skip multiple holidays
+
+    // Weekend starts
+    assert_eq!(model._get_text("A7"), *"44564"); // From Saturday
+    assert_eq!(model._get_text("A8"), *"44564"); // From Sunday
+
+    // Negative workdays
+    assert_eq!(model._get_text("A9"), *"44560"); // 3 days back
+    assert_eq!(model._get_text("A10"), *"44557"); // 5 days back with holidays
+
+    // Edge cases
+    assert_eq!(model._get_text("A11"), *"2"); // Early date
+    assert_eq!(model._get_text("A12"), *"100014"); // Large numbers
+
+    // Error cases
+    assert_eq!(model._get_text("A13"), *"#ERROR!");
+    assert_eq!(model._get_text("A14"), *"#ERROR!");
+    assert_eq!(model._get_text("A15"), *"#ERROR!");
+    assert_eq!(model._get_text("A16"), *"#NUM!");
+    assert_eq!(model._get_text("A17"), *"#NUM!");
+    assert_eq!(model._get_text("A18"), *"#NUM!"); // Invalid holiday
+}
+
+#[test]
+fn test_workday_intl_function() {
+    let mut model = new_empty_model();
+
+    // Test key weekend mask types
+    model._set("A1", "=WORKDAY.INTL(44560,1,1)"); // Numeric: standard (Sat-Sun)
+    model._set("A2", "=WORKDAY.INTL(44560,1,2)"); // Numeric: Sun-Mon
+    model._set("A3", "=WORKDAY.INTL(44560,1,\"0000001\")"); // String: Sunday only
+    model._set("A4", "=WORKDAY.INTL(44560,1,\"1100000\")"); // String: Mon-Tue
+
+    // Test with holidays
+    model._set("B1", "44561");
+    model._set("A5", "=WORKDAY.INTL(44560,2,1,B1)"); // Standard + holiday
+    model._set("A6", "=WORKDAY.INTL(44560,2,7,B1)"); // Fri-Sat + holiday
+
+    // Basic edge cases
+    model._set("A7", "=WORKDAY.INTL(44561,0,1)"); // Zero days
+    model._set("A8", "=WORKDAY.INTL(44565,-1,1)"); // Negative days
+
+    // Error cases
+    model._set("A9", "=WORKDAY.INTL()"); // Wrong arg count
+    model._set("A10", "=WORKDAY.INTL(44560,1,0)"); // Invalid weekend mask
+    model._set("A11", "=WORKDAY.INTL(44560,1,\"123\")"); // Invalid string mask
+    model._set("A12", "=WORKDAY.INTL(-1,1,1)"); // Invalid date
+
+    model.evaluate();
+
+    // Weekend mask functionality
+    assert_eq!(model._get_text("A1"), *"44561"); // Standard weekend
+    assert_eq!(model._get_text("A2"), *"44561"); // Sun-Mon weekend
+    assert_eq!(model._get_text("A3"), *"44561"); // Sunday only
+    assert_eq!(model._get_text("A4"), *"44561"); // Mon-Tue weekend
+
+    // With holidays
+    assert_eq!(model._get_text("A5"), *"44565"); // Skip holiday + standard weekend
+    assert_eq!(model._get_text("A6"), *"44564"); // Skip holiday + Fri-Sat weekend
+
+    // Edge cases
+    assert_eq!(model._get_text("A7"), *"44561"); // Zero days
+    assert_eq!(model._get_text("A8"), *"44564"); // Negative days
+
+    // Error cases
+    assert_eq!(model._get_text("A9"), *"#ERROR!");
+    assert_eq!(model._get_text("A10"), *"#NUM!");
+    assert_eq!(model._get_text("A11"), *"#VALUE!");
+    assert_eq!(model._get_text("A12"), *"#NUM!");
+}
+
+#[test]
+fn test_yearfrac_function() {
+    let mut model = new_empty_model();
+
+    // Test key basis values (not exhaustive - just verify parameter works)
+    model._set("A1", "=YEARFRAC(44561,44926)"); // Default (30/360)
+    model._set("A2", "=YEARFRAC(44561,44926,1)"); // Actual/actual
+    model._set("A3", "=YEARFRAC(44561,44926,4)"); // European 30/360
+
+    // Edge cases
+    model._set("A4", "=YEARFRAC(44561,44561,1)"); // Same date = 0
+    model._set("A6", "=YEARFRAC(44197,44562,1)"); // Exact year (2021)
+
+    // Error cases
+    model._set("A7", "=YEARFRAC()"); // Wrong arg count
+    model._set("A8", "=YEARFRAC(44561,44926,5)"); // Invalid basis
+    model._set("A9", "=YEARFRAC(-1,44926,1)"); // Invalid date
+
+    model.evaluate();
+
+    // Basic functionality (approximate values expected)
+    assert_eq!(model._get_text("A1"), *"1"); // About 1 year
+    assert_eq!(model._get_text("A2"), *"1"); // About 1 year
+    assert_eq!(model._get_text("A3"), *"1"); // About 1 year
+
+    // Edge cases
+    assert_eq!(model._get_text("A4"), *"0"); // Same date
+    assert_eq!(model._get_text("A6"), *"1"); // Exact year
+
+    // Error cases
+    assert_eq!(model._get_text("A7"), *"#ERROR!");
+    assert_eq!(model._get_text("A8"), *"#NUM!"); // Invalid basis should return #NUM!
+    assert_eq!(model._get_text("A9"), *"#NUM!");
+}
+
+#[test]
+fn test_isoweeknum_function() {
+    let mut model = new_empty_model();
+
+    // Basic functionality
+    model._set("A1", "=ISOWEEKNUM(44563)"); // Mid-week date
+    model._set("A2", "=ISOWEEKNUM(44561)"); // Year-end date
+
+    // Key ISO week boundaries (just critical cases)
+    model._set("A3", "=ISOWEEKNUM(44197)"); // Jan 1, 2021 (Fri) -> Week 53 of 2020
+    model._set("A4", "=ISOWEEKNUM(44200)"); // Jan 4, 2021 (Mon) -> Week 1 of 2021
+    model._set("A5", "=ISOWEEKNUM(44564)"); // Jan 3, 2022 (Mon) -> Week 1 of 2022
+
+    // Error cases
+    model._set("A6", "=ISOWEEKNUM()"); // Wrong arg count
+    model._set("A7", "=ISOWEEKNUM(-1)"); // Invalid date
+
+    model.evaluate();
+
+    // Basic functionality
+    assert_eq!(model._get_text("A1"), *"52");
+    assert_eq!(model._get_text("A2"), *"52");
+
+    // ISO week boundaries
+    assert_eq!(model._get_text("A3"), *"53"); // Week 53 of previous year
+    assert_eq!(model._get_text("A4"), *"1"); // Week 1 of current year
+    assert_eq!(model._get_text("A5"), *"1"); // Week 1 of next year
+
+    // Error cases
+    assert_eq!(model._get_text("A6"), *"#ERROR!");
+    assert_eq!(model._get_text("A7"), *"#NUM!");
+}

base/src/test/test_datedif_leap_month_end.rs

@@ -0,0 +1,33 @@
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_datedif_yd_leap_year_edge_cases() {
+    let mut model = new_empty_model();
+
+    // 29 Feb 2020 → 28 Feb 2021   (should be 0 days)
+    model._set("A1", "=DATEDIF(\"29/2/2020\", \"28/2/2021\", \"YD\")");
+
+    // 29 Feb 2020 → 1 Mar 2021    (should be 1 day)
+    model._set("A2", "=DATEDIF(\"29/2/2020\", \"2021-03-01\", \"YD\")");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("A1"), *"0");
+    assert_eq!(model._get_text("A2"), *"1");
+}
+
+#[test]
+fn test_datedif_md_month_end_edge_cases() {
+    let mut model = new_empty_model();
+
+    // 31 Jan 2021 → 28 Feb 2021 (non-leap) => 28
+    model._set("B1", "=DATEDIF(\"31/1/2021\", \"28/2/2021\", \"MD\")");
+
+    // 31 Jan 2020 → 29 Feb 2020 (leap) => 29
+    model._set("B2", "=DATEDIF(\"31/1/2020\", \"29/2/2020\", \"MD\")");
+
+    model.evaluate();
+
+    assert_eq!(model._get_text("B1"), *"28");
+    assert_eq!(model._get_text("B2"), *"29");
+}