1use super::{log1pf, logf, sqrtf};
2
3const 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))`.
10#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
11pub fn asinhf(mut x: f32) -> f32 {
12 let u = x.to_bits();
13 let i = u & 0x7fffffff;
14 let sign = (u >> 31) != 0;
15
16 /* |x| */
17 x = f32::from_bits(i);
18
19 if i >= 0x3f800000 + (12 << 23) {
20 /* |x| >= 0x1p12 or inf or nan */
21 x = logf(x) + LN2;
22 } else if i >= 0x3f800000 + (1 << 23) {
23 /* |x| >= 2 */
24 x = logf(2.0 * x + 1.0 / (sqrtf(x * x + 1.0) + x));
25 } else if i >= 0x3f800000 - (12 << 23) {
26 /* |x| >= 0x1p-12, up to 1.6ulp error in [0.125,0.5] */
27 x = log1pf(x + x * x / (sqrtf(x * x + 1.0) + 1.0));
28 } else {
29 /* |x| < 0x1p-12, raise inexact if x!=0 */
30 let x1p120 = f32::from_bits(0x7b800000);
31 force_eval!(x + x1p120);
32 }
33
34 if sign { -x } else { x }
35}
36