| use super::exp; |
| use super::expm1; |
| use super::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. |
| #[inline] |
| #[cfg_attr(all(test, 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) |
| } |
