arctanh.cpp

   1 #include "stdafx.h"
   2 #include "defs.h"
   3
   4 void
   5 eval_arctanh(void)
   6 {
   7         push(cadr(p1));
   8         eval();
   9         arctanh();
  10 }
  11
  12 void
  13 arctanh(void)
  14 {
  15         double d;
  16         save();
  17         p1 = pop();
  18         if (car(p1) == symbol(TANH)) {
  19                 push(cadr(p1));
  20                 restore();
  21                 return;
  22         }
  23         if (isdouble(p1)) {
  24                 d = p1->u.d;
  25                 if (d < -1.0 || d > 1.0)
  26                         stop("arctanh function argument is not in the interval [-1,1]");
  27                 d = log((1.0 + d) / (1.0 - d)) / 2.0;
  28                 push_double(d);
  29                 restore();
  30                 return;
  31         }
  32         if (iszero(p1)) {
  33                 push(zero);
  34                 restore();
  35                 return;
  36         }
  37         push_symbol(ARCTANH);
  38         push(p1);
  39         list(2);
  40         restore();
  41 }