UPDATE: Adds 12 more statistical functions:

* GAUSS
* HARMEAN
* KURT
* MAXA
* MEDIAN
* MINA
* RANK.EQ
* RANK.AVG
* SKEW
* SKEW.P
* SMALL
* LARGE

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)
+    }
+}