src/math/coshf.c

   1 #include "libm.h"
   2
   3 float coshf(float x)
   4 {
   5         union {float f; uint32_t i;} u = {.f = x};
   6         uint32_t w;
   7         float t;
   8
   9         /* |x| */
  10         u.i &= 0x7fffffff;
  11         x = u.f;
  12         w = u.i;
  13
  14         /* |x| < log(2) */
  15         if (w < 0x3f317217) {
  16                 if (w < 0x3f800000 - (12<<23)) {
  17                         FORCE_EVAL(x + 0x1p120f);
  18                         return 1;
  19                 }
  20                 t = expm1f(x);
  21                 return 1 + t*t/(2*(1+t));
  22         }
  23
  24         /* |x| < log(FLT_MAX) */
  25         if (w < 0x42b17217) {
  26                 t = expf(x);
  27                 return 0.5f*(t + 1/t);
  28         }
  29
  30         /* |x| > log(FLT_MAX) or nan */
  31         t = __expo2f(x, 1.0f);
  32         return t;
  33 }