tests/test_I_xgcd.cc

   1 #include "test_I.h"
   2
   3 int test_I_xgcd (int iterations)
   4 {
   5         int error = 0;
   6         int i;
   7         // Check against gcd.
   8         for (i = iterations; i > 0; i--) {
   9                 cl_I a = testrandom_I();
  10                 cl_I b = testrandom_I();
  11                 cl_I u, v;
  12                 cl_I g = xgcd(a,b,&u,&v);
  13                 ASSERT3(g == gcd(a,b), a,b,g);
  14                 ASSERT4(g == u*a+v*b, a,b,u,v);
  15                 if (a != 0 && b != 0) {
  16                         if (abs(a) == abs(b)) {
  17                                 ASSERT4((u == signum(a) && v == 0) || (u == 0 && v == signum(b)), a,b,u,v);
  18                         }
  19                         else if (mod(abs(a),abs(b)) == 0) {
  20                                 ASSERT4(u == 0 && v == signum(b), a,b,u,v);
  21                         }
  22                         else if (mod(abs(b),abs(a)) == 0) {
  23                                 ASSERT4(u == signum(a) && v == 0, a,b,u,v);
  24                         }
  25                         else {
  26                                 ASSERT4(abs(u) <= floor1(abs(b),2*g) && abs(v) <= floor1(abs(a),2*g), a,b,u,v);
  27                         }
  28                 }
  29         }
  30         return error;
  31 }