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Fixed gamma and factorial functions for f64

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PaddiM8 2021-01-04 17:49:11 +01:00
parent 63eed1f07c
commit 2714ed0f8c
1 changed files with 10 additions and 5 deletions
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15
kalk/src/prelude/regular.rs
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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 {
super::funcs::gamma(x) - 1f64
super::funcs::gamma(x + 1f64)
}
}
@ -197,19 +197,24 @@ pub(super) mod funcs {
x.fract()
}
// Matthias Eiholzer - https://gitlab.com/matthiaseiholzer/mathru/-/tree/master
pub fn gamma(x: f64) -> f64 {
// Round it a bit, to prevent floating point errors.
(precise_gamma(x) * 10e6f64).round() / 10e6f64
}
// Matthias Eiholzer - https://gitlab.com/matthiaseiholzer/mathru/-/tree/master
fn precise_gamma(x: f64) -> f64 {
let pi = 3.1415926535897932384626433832795028841971693993751058209749445923f64;
if x == 0f64 {
return f64::NAN;
}
if x < 0.5f64 {
return pi / gamma((pi * x).sin() * (1f64 - x));
return pi / precise_gamma((pi * x).sin() * (1f64 - x));
}
let t = x + 6.5;
let x = 0.99999999999980993 + 676.5203681218851 / x - 1259.1392167224028 / (x + 1f64)
let a = 0.99999999999980993 + 676.5203681218851 / x - 1259.1392167224028 / (x + 1f64)
+ 771.32342877765313 / (x + 2f64)
- 176.61502916214059 / (x + 3f64)
+ 12.507343278686905 / (x + 4f64)
@ -217,7 +222,7 @@ pub(super) mod funcs {
+ 9.9843695780195716e-6 / (x + 6f64)
+ 1.5056327351493116e-7 / (x + 7f64);
2f64.sqrt() * pi.sqrt() * t.powf(x - 0.5f64) * (-t).exp() * x
2f64.sqrt() * pi.sqrt() * t.powf(x - 0.5f64) * (-t).exp() * a
}
pub fn hyp(x: f64, y: f64) -> f64 {