/rust/registry/src/index.crates.io-1949cf8c6b5b557f/pxfm-0.1.29/src/gamma/lgammaf.rs
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1 | | /* |
2 | | * // Copyright (c) Radzivon Bartoshyk 8/2025. All rights reserved. |
3 | | * // |
4 | | * // Redistribution and use in source and binary forms, with or without modification, |
5 | | * // are permitted provided that the following conditions are met: |
6 | | * // |
7 | | * // 1. Redistributions of source code must retain the above copyright notice, this |
8 | | * // list of conditions and the following disclaimer. |
9 | | * // |
10 | | * // 2. Redistributions in binary form must reproduce the above copyright notice, |
11 | | * // this list of conditions and the following disclaimer in the documentation |
12 | | * // and/or other materials provided with the distribution. |
13 | | * // |
14 | | * // 3. Neither the name of the copyright holder nor the names of its |
15 | | * // contributors may be used to endorse or promote products derived from |
16 | | * // this software without specific prior written permission. |
17 | | * // |
18 | | * // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
19 | | * // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
20 | | * // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
21 | | * // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE |
22 | | * // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
23 | | * // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
24 | | * // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
25 | | * // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
26 | | * // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
27 | | * // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
28 | | */ |
29 | | use crate::common::is_integerf; |
30 | | use crate::gamma::lgamma_rf::lgamma_coref; |
31 | | |
32 | | /// Computes log(gamma(x)) |
33 | | /// |
34 | | /// ulp 0.5 |
35 | 0 | pub fn f_lgammaf(x: f32) -> f32 { |
36 | 0 | let xb = x.to_bits(); |
37 | 0 | if xb >= 0xffu32 << 23 || xb == 0 { |
38 | 0 | if x.is_infinite() { |
39 | 0 | return f32::INFINITY; |
40 | 0 | } |
41 | 0 | if x.is_nan() { |
42 | 0 | return f32::NAN; |
43 | 0 | } |
44 | 0 | if xb.wrapping_shl(1) == 0 { |
45 | 0 | return f32::INFINITY; |
46 | 0 | } |
47 | 0 | } |
48 | | |
49 | 0 | if is_integerf(x) { |
50 | 0 | if x == 2. || x == 1. { |
51 | 0 | return 0.; |
52 | 0 | } |
53 | 0 | if x.is_sign_negative() { |
54 | 0 | return f32::INFINITY; |
55 | 0 | } |
56 | 0 | } |
57 | | |
58 | 0 | lgamma_coref(x).0 as f32 |
59 | 0 | } |
60 | | |
61 | | #[cfg(test)] |
62 | | mod tests { |
63 | | use super::*; |
64 | | |
65 | | #[test] |
66 | | fn test_lgammaf() { |
67 | | assert_eq!(f_lgammaf(0.006919047), 4.969523); |
68 | | assert_eq!( |
69 | | f_lgammaf(0.000000000000000000000000000000000000000015425), |
70 | | 93.97255 |
71 | | ); |
72 | | assert_eq!(f_lgammaf(0.0), f32::INFINITY); |
73 | | assert_eq!(f_lgammaf(1.7506484), -0.0842405); |
74 | | assert_eq!(f_lgammaf(7.095007e-8), 16.461288); |
75 | | assert!(f_lgammaf(-12.).is_infinite()); |
76 | | assert_eq!(f_lgammaf(2.), 0.); |
77 | | assert_eq!(f_lgammaf(1.), 0.); |
78 | | assert_eq!(f_lgammaf(0.53), 0.5156078); |
79 | | assert_eq!(f_lgammaf(1.53), -0.11927056); |
80 | | assert_eq!(f_lgammaf(4.53), 2.4955146); |
81 | | assert_eq!(f_lgammaf(11.77), 16.94281); |
82 | | assert_eq!(f_lgammaf(22.77), 47.756233); |
83 | | assert_eq!(f_lgammaf(-0.53), 1.2684484); |
84 | | assert_eq!(f_lgammaf(-1.53), 0.84318066); |
85 | | assert_eq!(f_lgammaf(-4.53), -2.8570588); |
86 | | assert_eq!(f_lgammaf(-11.77), -17.850103); |
87 | | assert_eq!(f_lgammaf(-22.77), -49.323418); |
88 | | assert_eq!(f_lgammaf(f32::NEG_INFINITY), f32::INFINITY); |
89 | | } |
90 | | } |