vendor/compiler_builtins/libm/src/math/cosh.rs

   1 use super::exp;
   2 use super::expm1;
   3 use super::k_expo2;
   4
   5 /// Hyperbolic cosine (f64)
   6 ///
   7 /// Computes the hyperbolic cosine of the argument x.
   8 /// Is defined as `(exp(x) + exp(-x))/2`
   9 /// Angles are specified in radians.
  10 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
  11 pub fn cosh(mut x: f64) -> f64 {
  12     /* |x| */
  13     let mut ix = x.to_bits();
  14     ix &= 0x7fffffffffffffff;
  15     x = f64::from_bits(ix);
  16     let w = ix >> 32;
  17
  18     /* |x| < log(2) */
  19     if w < 0x3fe62e42 {
  20         if w < 0x3ff00000 - (26 << 20) {
  21             let x1p120 = f64::from_bits(0x4770000000000000);
  22             force_eval!(x + x1p120);
  23             return 1.;
  24         }
  25         let t = expm1(x); // exponential minus 1
  26         return 1. + t * t / (2. * (1. + t));
  27     }
  28
  29     /* |x| < log(DBL_MAX) */
  30     if w < 0x40862e42 {
  31         let t = exp(x);
  32         /* note: if x>log(0x1p26) then the 1/t is not needed */
  33         return 0.5 * (t + 1. / t);
  34     }
  35
  36     /* |x| > log(DBL_MAX) or nan */
  37     k_expo2(x)
  38 }