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))`.
10 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
asinhf(mut x: f32) -> f3211 pub 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 {
35         -x
36     } else {
37         x
38     }
39 }
40