src/math/tanhl.c

   1 #include "libm.h"
   2
   3 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
   4 long double tanhl(long double x)
   5 {
   6         return tanh(x);
   7 }
   8 #elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
   9 long double tanhl(long double x)
  10 {
  11         union ldshape u = {x};
  12         unsigned ex = u.i.se & 0x7fff;
  13         unsigned sign = u.i.se & 0x8000;
  14         uint32_t w;
  15         long double t;
  16
  17         /* x = |x| */
  18         u.i.se = ex;
  19         x = u.f;
  20         w = u.i.m >> 32;
  21
  22         if (ex > 0x3ffe || (ex == 0x3ffe && w > 0x8c9f53d5)) {
  23                 /* |x| > log(3)/2 ~= 0.5493 or nan */
  24                 if (ex >= 0x3fff+5) {
  25                         /* |x| >= 32 */
  26                         t = 1 + 0/(x + 0x1p-120f);
  27                 } else {
  28                         t = expm1l(2*x);
  29                         t = 1 - 2/(t+2);
  30                 }
  31         } else if (ex > 0x3ffd || (ex == 0x3ffd && w > 0x82c577d4)) {
  32                 /* |x| > log(5/3)/2 ~= 0.2554 */
  33                 t = expm1l(2*x);
  34                 t = t/(t+2);
  35         } else {
  36                 /* |x| is small */
  37                 t = expm1l(-2*x);
  38                 t = -t/(t+2);
  39         }
  40         return sign ? -t : t;
  41 }
  42 #elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
  43 // TODO: broken implementation to make things compile
  44 long double tanhl(long double x)
  45 {
  46         return tanh(x);
  47 }
  48 #endif