sirtimbly/IronCalc
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

UPDATE: Adds simple functions (#489)

Browse Source 
Exp, Fact, Factdouble and sign
This commit is contained in:
Nicolás Hatcher Andrés
2025-10-30 18:28:07 +01:00
committed by GitHub
parent f2f4992230
commit 7e379e24e7
6 changed files with 141 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
base/src/expressions/parser/static_analysis.rs
View File

@@ -842,6 +842,10 @@ fn get_function_args_signature(kind: &Function, arg_count: usize) -> Vec<Signatu
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),
}
}
@@ -1072,5 +1076,9 @@ fn static_analysis_on_function(kind: &Function, args: &[Node]) -> StaticResult {
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),
}
}

2
base/src/functions/engineering/mod.rs
View File

@@ -5,3 +5,5 @@ mod convert;
mod misc;
mod number_basis;
mod transcendental;
pub use transcendental::{fact, fact_double};

106
base/src/functions/engineering/transcendental/gamma.rs Normal file
View File

@@ -0,0 +1,106 @@
use std::f64::consts::PI;
// FIXME: Please do a better approximation
/// Lanczos approximation for Gamma(z).
/// Valid for z > 0. For z <= 0 use `gamma` below (which does reflection).
fn gamma_lanczos(z: f64) -> f64 {
const COEFFS: [f64; 9] = [
0.999_999_999_999_809_9,
676.5203681218851,
-1259.1392167224028,
771.323_428_777_653_1,
-176.615_029_162_140_6,
12.507343278686905,
-0.13857109526572012,
9.984_369_578_019_572e-6,
1.5056327351493116e-7,
];
let g = 7.0;
let mut x = COEFFS[0];
// sum_{i=1}^{n} c_i / (z + i)
for (i, c) in COEFFS.iter().enumerate().skip(1) {
x += c / (z + i as f64);
}
let t = z + g + 0.5;
// √(2π) * t^(z+0.5) * e^{-t} * x
(2.0 * PI).sqrt() * t.powf(z + 0.5) * (-t).exp() * x
}
/// Gamma function for all real x (except poles),
/// using Lanczos + reflection formula.
fn gamma(x: f64) -> f64 {
if x.is_sign_negative() {
// Reflection formula: Γ(x) = π / (sin(πx) * Γ(1 - x))
// Beware of sin(πx) near zeros.
let sin_pix = (PI * x).sin();
if sin_pix == 0.0 {
return f64::NAN;
}
PI / (sin_pix * gamma_lanczos(1.0 - x))
} else if x == 0.0 {
f64::INFINITY
} else {
gamma_lanczos(x)
}
}
/// Factorial for real x: x! = Γ(x+1)
pub fn fact(x: f64) -> f64 {
if x < 0.0 {
return f64::NAN;
}
gamma(x + 1.0)
}
/// Double factorial for real x.
///
/// Strategy:
/// 1. If x is (almost) integer and >= 0 → do exact product (stable, no surprises)
/// 2. Else:
/// - If x is “even-ish”: x = 2t → x!! = 2^t * Γ(t+1)
/// - If x is “odd-ish”: x = 2t-1 → x!! = Γ(2t+1) / (2^t * Γ(t+1))
pub fn fact_double(x: f64) -> f64 {
if x < 0.0 {
return f64::NAN;
}
let xi = x.round();
let is_int = (x - xi).abs() < 1e-9;
if is_int {
// integer path
let mut acc = 1.0;
let mut k = xi;
while k > 1.0 {
acc *= k;
k -= 2.0;
}
return acc;
}
// non-integer path: use continuous extension
let frac = x % 2.0;
// even-ish if close to 0 mod 2
if frac.abs() < 1e-6 || (frac - 2.0).abs() < 1e-6 {
// x = 2t
let t = x / 2.0;
2f64.powf(t) * gamma(t + 1.0)
} else if (frac - 1.0).abs() < 1e-6 || (frac + 1.0).abs() < 1e-6 {
// x = 2t - 1 => t = (x+1)/2
let t = (x + 1.0) / 2.0;
// (2t - 1)!! = Γ(2t + 1) / (2^t Γ(t+1))
// but 2t - 1 = x, so 2t + 1 = x + 2
let num = gamma(x + 2.0);
let den = 2f64.powf(t) * gamma(t + 1.0);
num / den
} else {
// x is neither clearly even-ish nor odd-ish – fall back to a generic formula.
// A safe thing to do is to treat it as even-ish:
let t = x / 2.0;
2f64.powf(t) * gamma(t + 1.0)
}
}

2
base/src/functions/engineering/transcendental/mod.rs
View File

@@ -5,6 +5,7 @@ mod bessel_jn_yn;
mod bessel_k;
mod bessel_util;
mod erf;
mod gamma;
#[cfg(test)]
mod test_bessel;
@@ -14,3 +15,4 @@ 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;
pub use gamma::{fact, fact_double};

5
base/src/functions/mathematical.rs
View File

@@ -2,6 +2,7 @@ use crate::cast::NumberOrArray;
use crate::constants::{LAST_COLUMN, LAST_ROW};
use crate::expressions::parser::ArrayNode;
use crate::expressions::types::CellReferenceIndex;
use crate::functions::engineering::{fact, fact_double};
use crate::number_format::to_precision;
use crate::single_number_fn;
use crate::{
@@ -454,6 +455,10 @@ impl Model {
} else {
Ok(1.0 / f64::cosh(f))
});
single_number_fn!(fn_exp, |f: f64| Ok(f64::exp(f)));
single_number_fn!(fn_fact, |f| Ok(fact(f)));
single_number_fn!(fn_factdouble, |f| Ok(fact_double(f)));
single_number_fn!(fn_sign, |f| Ok(f64::signum(f)));
pub(crate) fn fn_pi(&mut self, args: &[Node], cell: CellReferenceIndex) -> CalcResult {
if !args.is_empty() {

39
base/src/functions/mod.rs
View File

@@ -85,6 +85,11 @@ pub enum Function {
Sec,
Sech,
Exp,
Fact,
Factdouble,
Sign,
// Information
ErrorType,
Formulatext,
@@ -278,7 +283,7 @@ pub enum Function {
}
impl Function {
pub fn into_iter() -> IntoIter<Function, 223> {
pub fn into_iter() -> IntoIter<Function, 227> {
[
Function::And,
Function::False,
@@ -320,6 +325,10 @@ impl Function {
Function::Sec,
Function::Sech,
Function::Power,
Function::Exp,
Function::Fact,
Function::Factdouble,
Function::Sign,
Function::Max,
Function::Min,
Function::Product,
@@ -836,7 +845,6 @@ impl fmt::Display for Function {
Function::Asinh => write!(f, "ASINH"),
Function::Acosh => write!(f, "ACOSH"),
Function::Atanh => write!(f, "ATANH"),
Function::Acot => write!(f, "ACOT"),
Function::Acoth => write!(f, "ACOTH"),
Function::Cot => write!(f, "COT"),
@@ -845,7 +853,6 @@ impl fmt::Display for Function {
Function::Csch => write!(f, "CSCH"),
Function::Sec => write!(f, "SEC"),
Function::Sech => write!(f, "SECH"),
Function::Abs => write!(f, "ABS"),
Function::Pi => write!(f, "PI"),
Function::Sqrt => write!(f, "SQRT"),
@@ -910,7 +917,6 @@ impl fmt::Display for Function {
Function::Isformula => write!(f, "ISFORMULA"),
Function::Type => write!(f, "TYPE"),
Function::Sheet => write!(f, "SHEET"),
Function::Average => write!(f, "AVERAGE"),
Function::Averagea => write!(f, "AVERAGEA"),
Function::Averageif => write!(f, "AVERAGEIF"),
@@ -1035,8 +1041,11 @@ impl fmt::Display for Function {
Function::Convert => write!(f, "CONVERT"),
Function::Delta => write!(f, "DELTA"),
Function::Gestep => write!(f, "GESTEP"),
Function::Subtotal => write!(f, "SUBTOTAL"),
Function::Exp => write!(f, "EXP"),
Function::Fact => write!(f, "FACT"),
Function::Factdouble => write!(f, "FACTDOUBLE"),
Function::Sign => write!(f, "SIGN"),
}
}
}
@@ -1065,7 +1074,6 @@ impl Model {
cell: CellReferenceIndex,
) -> CalcResult {
match kind {
// Logical
Function::And => self.fn_and(args, cell),
Function::False => self.fn_false(args, cell),
Function::If => self.fn_if(args, cell),
@@ -1077,34 +1085,27 @@ impl Model {
Function::Switch => self.fn_switch(args, cell),
Function::True => self.fn_true(args, cell),
Function::Xor => self.fn_xor(args, cell),
// Math and trigonometry
Function::Log => self.fn_log(args, cell),
Function::Log10 => self.fn_log10(args, cell),
Function::Ln => self.fn_ln(args, cell),
Function::Sin => self.fn_sin(args, cell),
Function::Cos => self.fn_cos(args, cell),
Function::Tan => self.fn_tan(args, cell),
Function::Asin => self.fn_asin(args, cell),
Function::Acos => self.fn_acos(args, cell),
Function::Atan => self.fn_atan(args, cell),
Function::Sinh => self.fn_sinh(args, cell),
Function::Cosh => self.fn_cosh(args, cell),
Function::Tanh => self.fn_tanh(args, cell),
Function::Asinh => self.fn_asinh(args, cell),
Function::Acosh => self.fn_acosh(args, cell),
Function::Atanh => self.fn_atanh(args, cell),
Function::Pi => self.fn_pi(args, cell),
Function::Abs => self.fn_abs(args, cell),
Function::Sqrt => self.fn_sqrt(args, cell),
Function::Sqrtpi => self.fn_sqrtpi(args, cell),
Function::Atan2 => self.fn_atan2(args, cell),
Function::Power => self.fn_power(args, cell),
Function::Max => self.fn_max(args, cell),
Function::Min => self.fn_min(args, cell),
Function::Product => self.fn_product(args, cell),
@@ -1116,8 +1117,6 @@ impl Model {
Function::Sum => self.fn_sum(args, cell),
Function::Sumif => self.fn_sumif(args, cell),
Function::Sumifs => self.fn_sumifs(args, cell),
// Lookup and Reference
Function::Choose => self.fn_choose(args, cell),
Function::Column => self.fn_column(args, cell),
Function::Columns => self.fn_columns(args, cell),
@@ -1131,7 +1130,6 @@ impl Model {
Function::Rows => self.fn_rows(args, cell),
Function::Vlookup => self.fn_vlookup(args, cell),
Function::Xlookup => self.fn_xlookup(args, cell),
// Text
Function::Concatenate => self.fn_concatenate(args, cell),
Function::Exact => self.fn_exact(args, cell),
Function::Value => self.fn_value(args, cell),
@@ -1149,7 +1147,6 @@ impl Model {
Function::Trim => self.fn_trim(args, cell),
Function::Unicode => self.fn_unicode(args, cell),
Function::Upper => self.fn_upper(args, cell),
// Information
Function::Isnumber => self.fn_isnumber(args, cell),
Function::Isnontext => self.fn_isnontext(args, cell),
Function::Istext => self.fn_istext(args, cell),
@@ -1167,7 +1164,6 @@ impl Model {
Function::Isformula => self.fn_isformula(args, cell),
Function::Type => self.fn_type(args, cell),
Function::Sheet => self.fn_sheet(args, cell),
// Statistical
Function::Average => self.fn_average(args, cell),
Function::Averagea => self.fn_averagea(args, cell),
Function::Averageif => self.fn_averageif(args, cell),
@@ -1180,7 +1176,6 @@ impl Model {
Function::Maxifs => self.fn_maxifs(args, cell),
Function::Minifs => self.fn_minifs(args, cell),
Function::Geomean => self.fn_geomean(args, cell),
// Date and Time
Function::Year => self.fn_year(args, cell),
Function::Day => self.fn_day(args, cell),
Function::Eomonth => self.fn_eomonth(args, cell),
@@ -1206,7 +1201,6 @@ impl Model {
Function::WorkdayIntl => self.fn_workday_intl(args, cell),
Function::Yearfrac => self.fn_yearfrac(args, cell),
Function::Isoweeknum => self.fn_isoweeknum(args, cell),
// Financial
Function::Pmt => self.fn_pmt(args, cell),
Function::Pv => self.fn_pv(args, cell),
Function::Rate => self.fn_rate(args, cell),
@@ -1240,7 +1234,6 @@ impl Model {
Function::Db => self.fn_db(args, cell),
Function::Cumprinc => self.fn_cumprinc(args, cell),
Function::Cumipmt => self.fn_cumipmt(args, cell),
// Engineering
Function::Besseli => self.fn_besseli(args, cell),
Function::Besselj => self.fn_besselj(args, cell),
Function::Besselk => self.fn_besselk(args, cell),
@@ -1304,6 +1297,10 @@ impl Model {
Function::Csch => self.fn_csch(args, cell),
Function::Sec => self.fn_sec(args, cell),
Function::Sech => self.fn_sech(args, cell),
Function::Exp => self.fn_exp(args, cell),
Function::Fact => self.fn_fact(args, cell),
Function::Factdouble => self.fn_factdouble(args, cell),
Function::Sign => self.fn_sign(args, cell),
}
}
}