1 | use super::expm1f; |
2 | |
3 | #[cfg_attr (all(test, assert_no_panic), no_panic::no_panic)] |
4 | pub fn tanhf(mut x: f32) -> f32 { |
5 | /* x = |x| */ |
6 | let mut ix = x.to_bits(); |
7 | let sign = (ix >> 31) != 0; |
8 | ix &= 0x7fffffff; |
9 | x = f32::from_bits(ix); |
10 | let w = ix; |
11 | |
12 | let tt = if w > 0x3f0c9f54 { |
13 | /* |x| > log(3)/2 ~= 0.5493 or nan */ |
14 | if w > 0x41200000 { |
15 | /* |x| > 10 */ |
16 | 1. + 0. / x |
17 | } else { |
18 | let t = expm1f(2. * x); |
19 | 1. - 2. / (t + 2.) |
20 | } |
21 | } else if w > 0x3e82c578 { |
22 | /* |x| > log(5/3)/2 ~= 0.2554 */ |
23 | let t = expm1f(2. * x); |
24 | t / (t + 2.) |
25 | } else if w >= 0x00800000 { |
26 | /* |x| >= 0x1p-126 */ |
27 | let t = expm1f(-2. * x); |
28 | -t / (t + 2.) |
29 | } else { |
30 | /* |x| is subnormal */ |
31 | force_eval!(x * x); |
32 | x |
33 | }; |
34 | if sign { |
35 | -tt |
36 | } else { |
37 | tt |
38 | } |
39 | } |
40 | |