bessely.cpp

   1 //-----------------------------------------------------------------------------
   2 //
   3 //      Bessel Y function
   4 //
   5 //      Input:          tos-2           x       (can be a symbol or expr)
   6 //
   7 //                      tos-1           n
   8 //
   9 //      Output:         Result on stack
  10 //
  11 //-----------------------------------------------------------------------------
  12
  13 #include "stdafx.h"
  14 #include "defs.h"
  15
  16 void
  17 eval_bessely(void)
  18 {
  19         push(cadr(p1));
  20         eval();
  21         push(caddr(p1));
  22         eval();
  23         bessely();
  24 }
  25
  26 void
  27 bessely(void)
  28 {
  29         save();
  30         yybessely();
  31         restore();
  32 }
  33
  34 #define X p1
  35 #define N p2
  36
  37 void
  38 yybessely(void)
  39 {
  40         double d;
  41         int n;
  42
  43         N = pop();
  44         X = pop();
  45
  46         push(N);
  47         n = pop_integer();
  48
  49         if (isdouble(X) && n != (int) 0x80000000) {
  50                 d = yn(n, X->u.d);
  51                 push_double(d);
  52                 return;
  53         }
  54
  55         if (isnegativeterm(N)) {
  56                 push_integer(-1);
  57                 push(N);
  58                 power();
  59                 push_symbol(BESSELY);
  60                 push(X);
  61                 push(N);
  62                 negate();
  63                 list(3);
  64                 multiply();
  65                 return;
  66         }
  67         push_symbol(BESSELY);
  68         push(X);
  69         push(N);
  70         list(3);
  71         return;
  72 }