2.9BSD - /usr/src/lib/m/tanh.c

   1: /*
   2: 	tanh(arg) computes the hyperbolic tangent of its floating
   3: 	point argument.
   4: 
   5: 	sinh and cosh are called except for large arguments, which
   6: 	would cause overflow improperly.
   7: */
   8: 
   9: double sinh(), cosh();
  10: 
  11: double
  12: tanh(arg)
  13: double arg;
  14: {
  15:     double sign;
  16: 
  17:     sign = 1.;
  18:     if(arg < 0.){
  19:         arg = -arg;
  20:         sign = -1.;
  21:     }
  22: 
  23:     if(arg > 21.)
  24:         return(sign);
  25: 
  26:     return(sign*sinh(arg)/cosh(arg));
  27: }

Defined functions