| use super::{exp, expm1, k_expo2}; | |
| /// Hyperbolic cosine (f64) | |
| /// | |
| /// Computes the hyperbolic cosine of the argument x. | |
| /// Is defined as `(exp(x) + exp(-x))/2` | |
| /// Angles are specified in radians. | |
| #[cfg_attr(assert_no_panic, no_panic::no_panic)] | |
| pub fn cosh(mut x: f64) -> f64 { | |
| /* |x| */ | |
| let mut ix = x.to_bits(); | |
| ix &= 0x7fffffffffffffff; | |
| x = f64::from_bits(ix); | |
| let w = ix >> 32; | |
| /* |x| < log(2) */ | |
| if w < 0x3fe62e42 { | |
| if w < 0x3ff00000 - (26 << 20) { | |
| let x1p120 = f64::from_bits(0x4770000000000000); | |
| force_eval!(x + x1p120); | |
| return 1.; | |
| } | |
| let t = expm1(x); // exponential minus 1 | |
| return 1. + t * t / (2. * (1. + t)); | |
| } | |
| /* |x| < log(DBL_MAX) */ | |
| if w < 0x40862e42 { | |
| let t = exp(x); | |
| /* note: if x>log(0x1p26) then the 1/t is not needed */ | |
| return 0.5 * (t + 1. / t); | |
| } | |
| /* |x| > log(DBL_MAX) or nan */ | |
| k_expo2(x) | |
| } |