/rust/registry/src/index.crates.io-1949cf8c6b5b557f/pxfm-0.1.25/src/hyperbolic/acoshf.rs
Line | Count | Source |
1 | | /* |
2 | | * // Copyright (c) Radzivon Bartoshyk 7/2025. 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::f_fmla; |
30 | | use crate::hyperbolic::asinhf::log_eval; |
31 | | |
32 | | /// Hyperbolic arc cosine function |
33 | | /// |
34 | | /// Max ULP 0.5 |
35 | | #[inline] |
36 | 0 | pub fn f_acoshf(x: f32) -> f32 { |
37 | 0 | if x <= 1.0 { |
38 | 0 | if x == 1.0 { |
39 | 0 | return 0.0; |
40 | 0 | } |
41 | | // x < 1. |
42 | 0 | return f32::NAN; |
43 | 0 | } |
44 | | |
45 | 0 | if !x.is_finite() { |
46 | 0 | return x; |
47 | 0 | } |
48 | 0 | let x_d = x as f64; |
49 | | // acosh(x) = log(x + sqrt(x^2 - 1)) |
50 | 0 | log_eval(x_d + (f_fmla(x_d, x_d, -1.0).sqrt())) as f32 |
51 | 0 | } |
52 | | |
53 | | #[cfg(test)] |
54 | | mod tests { |
55 | | use super::*; |
56 | | |
57 | | #[test] |
58 | | fn test_f_acoshf() { |
59 | | assert_eq!(f_acoshf(2.0), 1.316958); |
60 | | assert!(f_acoshf(0.5).is_nan()); |
61 | | } |
62 | | } |