1 use super::{exp, expm1, k_expo2}; 2 3 /// Hyperbolic cosine (f64) 4 /// 5 /// Computes the hyperbolic cosine of the argument x. 6 /// Is defined as `(exp(x) + exp(-x))/2` 7 /// Angles are specified in radians. 8 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] cosh(mut x: f64) -> f649pub fn cosh(mut x: f64) -> f64 { 10 /* |x| */ 11 let mut ix = x.to_bits(); 12 ix &= 0x7fffffffffffffff; 13 x = f64::from_bits(ix); 14 let w = ix >> 32; 15 16 /* |x| < log(2) */ 17 if w < 0x3fe62e42 { 18 if w < 0x3ff00000 - (26 << 20) { 19 let x1p120 = f64::from_bits(0x4770000000000000); 20 force_eval!(x + x1p120); 21 return 1.; 22 } 23 let t = expm1(x); // exponential minus 1 24 return 1. + t * t / (2. * (1. + t)); 25 } 26 27 /* |x| < log(DBL_MAX) */ 28 if w < 0x40862e42 { 29 let t = exp(x); 30 /* note: if x>log(0x1p26) then the 1/t is not needed */ 31 return 0.5 * (t + 1. / t); 32 } 33 34 /* |x| > log(DBL_MAX) or nan */ 35 k_expo2(x) 36 } 37