src/math/acoshl.c

   1 #include "libm.h"
   2
   3 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
   4 long double acoshl(long double x)
   5 {
   6         return acosh(x);
   7 }
   8 #elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
   9 /* acosh(x) = log(x + sqrt(x*x-1)) */
  10 long double acoshl(long double x)
  11 {
  12         union ldshape u = {x};
  13         int e = u.i.se & 0x7fff;
  14
  15         if (e < 0x3fff + 1)
  16                 /* |x| < 2, invalid if x < 1 or nan */
  17                 return log1pl(x-1 + sqrtl((x-1)*(x-1)+2*(x-1)));
  18         if (e < 0x3fff + 32)
  19                 /* |x| < 0x1p32 */
  20                 return logl(2*x - 1/(x+sqrtl(x*x-1)));
  21         return logl(x) + 0.693147180559945309417232121458176568L;
  22 }
  23 #elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
  24 // TODO: broken implementation to make things compile
  25 long double acoshl(long double x)
  26 {
  27         return acosh(x);
  28 }
  29 #endif