sgn.cpp

   1 #include "defs.h"
   2
   3 void
   4 eval_sgn(void)
   5 {
   6         push(cadr(p1));
   7         eval();
   8         sgn();
   9 }
  10
  11 void
  12 sgn(void)
  13 {
  14         save();
  15
  16         p1 = pop();
  17
  18         if (!isnum(p1)) {
  19                 push_symbol(SGN);
  20                 push(p1);
  21                 list(2);
  22         } else if (iszero(p1))
  23                 push_integer(0);
  24         else if (isnegativenumber(p1))
  25                 push_integer(-1);
  26         else
  27                 push_integer(1);
  28
  29         restore();
  30 }