vendor/libm/src/math/coshf.rs

   1 use super::expf;
   2 use super::expm1f;
   3 use super::k_expo2f;
   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 #[inline]
  11 #[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
  12 pub fn coshf(mut x: f32) -> f32 {
  13     let x1p120 = f32::from_bits(0x7b800000); // 0x1p120f === 2 ^ 120
  14
  15     /* |x| */
  16     let mut ix = x.to_bits();
  17     ix &= 0x7fffffff;
  18     x = f32::from_bits(ix);
  19     let w = ix;
  20
  21     /* |x| < log(2) */
  22     if w < 0x3f317217 {
  23         if w < (0x3f800000 - (12 << 23)) {
  24             force_eval!(x + x1p120);
  25             return 1.;
  26         }
  27         let t = expm1f(x);
  28         return 1. + t * t / (2. * (1. + t));
  29     }
  30
  31     /* |x| < log(FLT_MAX) */
  32     if w < 0x42b17217 {
  33         let t = expf(x);
  34         return 0.5 * (t + 1. / t);
  35     }
  36
  37     /* |x| > log(FLT_MAX) or nan */
  38     k_expo2f(x)
  39 }