1 use super::{log1pf, logf, sqrtf};
2 
3 const LN2: f32 = 0.693147180559945309417232121458176568;
4 
5 /* asinh(x) = sign(x)*log(|x|+sqrt(x*x+1)) ~= x - x^3/6 + o(x^5) */
6 /// Inverse hyperbolic sine (f32)
7 ///
8 /// Calculates the inverse hyperbolic sine of `x`.
9 /// Is defined as `sgn(x)*log(|x|+sqrt(x*x+1))`.
asinhf(mut x: f32) -> f3210 pub fn asinhf(mut x: f32) -> f32 {
11     let u = x.to_bits();
12     let i = u & 0x7fffffff;
13     let sign = (u >> 31) != 0;
14 
15     /* |x| */
16     x = f32::from_bits(i);
17 
18     if i >= 0x3f800000 + (12 << 23) {
19         /* |x| >= 0x1p12 or inf or nan */
20         x = logf(x) + LN2;
21     } else if i >= 0x3f800000 + (1 << 23) {
22         /* |x| >= 2 */
23         x = logf(2.0 * x + 1.0 / (sqrtf(x * x + 1.0) + x));
24     } else if i >= 0x3f800000 - (12 << 23) {
25         /* |x| >= 0x1p-12, up to 1.6ulp error in [0.125,0.5] */
26         x = log1pf(x + x * x / (sqrtf(x * x + 1.0) + 1.0));
27     } else {
28         /* |x| < 0x1p-12, raise inexact if x!=0 */
29         let x1p120 = f32::from_bits(0x7b800000);
30         force_eval!(x + x1p120);
31     }
32 
33     if sign {
34         -x
35     } else {
36         x
37     }
38 }
39