erf.cpp

   1 //-----------------------------------------------------------------------------
   2 //
   3 //      Author : philippe.billet@noos.fr
   4 //
   5 //      Error function erf(x)
   6 //      erf(-x)=erf(x)
   7 //
   8 //-----------------------------------------------------------------------------
   9
  10 #include "stdafx.h"
  11 #include "defs.h"
  12 static void yyerf(void);
  13
  14 void
  15 eval_erf(void)
  16 {
  17         push(cadr(p1));
  18         eval();
  19         yerf();
  20 }
  21
  22 void
  23 yerf(void)
  24 {
  25         save();
  26         yyerf();
  27         restore();
  28 }
  29
  30 static void
  31 yyerf(void)
  32 {
  33         double d;
  34
  35         p1 = pop();
  36
  37         if (isdouble(p1)) {
  38                 d = 1.0 - erfc(p1->u.d);
  39                 push_double(d);
  40                 return;
  41         }
  42
  43         if (isnegativeterm(p1)) {
  44                 push_symbol(ERF);
  45                 push(p1);
  46                 negate();
  47                 list(2);
  48                 negate();
  49                 return;
  50         }
  51
  52         push_symbol(ERF);
  53         push(p1);
  54         list(2);
  55         return;
  56 }
  57
  58 #if SELFTEST
  59
  60 static char *s[] = {
  61
  62         "erf(a)",
  63         "erf(a)",
  64
  65         "erf(0.0) + 1",         // add 1 to round off
  66         "1",
  67
  68         "float(erf(0)) + 1",    // add 1 to round off
  69         "1",
  70 #if 0
  71         "float(erf(1))",
  72         "0.842701",
  73 #endif
  74 };
  75
  76 void
  77 test_erf(void)
  78 {
  79         test(__FILE__, s, sizeof s / sizeof (char *));
  80 }
  81
  82 #endif