1 | use super::expf; |
2 | use super::expm1f; |
3 | use super::k_expo2f; |
4 | |
5 | /// Hyperbolic cosine (f64) |
6 | /// |
7 | /// Computes the hyperbolic cosine of the argument x. |
8 | /// Is defined as `(exp(x) + exp(-x))/2` |
9 | /// Angles are specified in radians. |
10 | #[cfg_attr (all(test, assert_no_panic), no_panic::no_panic)] |
11 | pub fn coshf(mut x: f32) -> f32 { |
12 | let x1p120 = f32::from_bits(0x7b800000); // 0x1p120f === 2 ^ 120 |
13 | |
14 | /* |x| */ |
15 | let mut ix = x.to_bits(); |
16 | ix &= 0x7fffffff; |
17 | x = f32::from_bits(ix); |
18 | let w = ix; |
19 | |
20 | /* |x| < log(2) */ |
21 | if w < 0x3f317217 { |
22 | if w < (0x3f800000 - (12 << 23)) { |
23 | force_eval!(x + x1p120); |
24 | return 1.; |
25 | } |
26 | let t = expm1f(x); |
27 | return 1. + t * t / (2. * (1. + t)); |
28 | } |
29 | |
30 | /* |x| < log(FLT_MAX) */ |
31 | if w < 0x42b17217 { |
32 | let t = expf(x); |
33 | return 0.5 * (t + 1. / t); |
34 | } |
35 | |
36 | /* |x| > log(FLT_MAX) or nan */ |
37 | k_expo2f(x) |
38 | } |
39 | |