Implemented prelude gamma function for kalk without rug

This commit is contained in:
PaddiM8 2021-01-02 19:25:10 +01:00
parent 66950779de
commit 0c802df3d5

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@ -96,7 +96,7 @@ fn from_angle_unit(context: &mut interpreter::Context, x: f64, angle_unit: &str)
pub mod special_funcs {
pub fn factorial(x: f64) -> f64 {
unimplemented!()
funcs::gamma(x) - 1
}
}
@ -197,8 +197,27 @@ pub(super) mod funcs {
x.fract()
}
// Matthias Eiholzer - https://gitlab.com/matthiaseiholzer/mathru/-/tree/master
pub fn gamma(x: f64) -> f64 {
unimplemented!()
let pi = 3.1415926535897932384626433832795028841971693993751058209749445923f64;
if x == 0.0 {
return f64::NAN;
}
if x < 0.5 {
return pi / ((pi * x).sin() * (1.0 - x).gamma());
}
let t = x + 6.5;
let x = 0.99999999999980993 + 676.5203681218851 / x - 1259.1392167224028 / (x + 1.0)
+ 771.32342877765313 / (x + 2.0)
- 176.61502916214059 / (x + 3.0)
+ 12.507343278686905 / (x + 4.0)
- 0.13857109526572012 / (x + 5.0)
+ 9.9843695780195716e-6 / (x + 6.0)
+ 1.5056327351493116e-7 / (x + 7.0);
2.0.sqrt() * pi.sqrt() * t.pow((x - 0.5)) * (-t).exp() * x
}
pub fn hyp(x: f64, y: f64) -> f64 {