lcm.cpp

   1 // Find the least common multiple of two expressions.
   2
   3 #include "stdafx.h"
   4 #include "defs.h"
   5
   6 void
   7 eval_lcm(void)
   8 {
   9         p1 = cdr(p1);
  10         push(car(p1));
  11         eval();
  12         p1 = cdr(p1);
  13         while (iscons(p1)) {
  14                 push(car(p1));
  15                 eval();
  16                 lcm();
  17                 p1 = cdr(p1);
  18         }
  19 }
  20
  21 void
  22 lcm(void)
  23 {
  24         int x;
  25         x = expanding;
  26         save();
  27         yylcm();
  28         restore();
  29         expanding = x;
  30 }
  31
  32 void
  33 yylcm(void)
  34 {
  35         expanding = 1;
  36
  37         p2 = pop();
  38         p1 = pop();
  39
  40         push(p1);
  41         push(p2);
  42         gcd();
  43
  44         push(p1);
  45         divide();
  46
  47         push(p2);
  48         divide();
  49
  50         inverse();
  51 }
  52
  53 #if SELFTEST
  54
  55 static char *s[] = {
  56
  57         "lcm(4,6)",
  58         "12",
  59
  60         "lcm(4*x,6*x*y)",
  61         "12*x*y",
  62
  63         // multiple arguments
  64
  65         "lcm(2,3,4)",
  66         "12",
  67 };
  68
  69 void
  70 test_lcm(void)
  71 {
  72         test(__FILE__, s, sizeof (s) / sizeof (char *));
  73 }
  74
  75 #endif