reactos/lib/sdk/crt/math/tanh.c

   1 /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
   2
   3 #include <math.h>
   4
   5 #ifdef _MSC_VER
   6 #pragma function(tanh)
   7 #endif
   8
   9 /*
  10  * @implemented
  11  */
  12 double tanh(double x)
  13 {
  14   if (x > 50)
  15     return 1;
  16   else if (x < -50)
  17     return -1;
  18   else
  19   {
  20     const double ebig = exp(x);
  21     const double esmall = 1.0/ebig;
  22     return (ebig - esmall) / (ebig + esmall);
  23   }
  24 }