int test_main(void)
{
   const long TESTCOUNT = 1000;
   const double RANDMAX = (double)RAND_MAX;
   const double DEG2RAD = M_PI / 180.0;

   pair_coord * mem = (pair_coord*)malloc(TESTCOUNT * sizeof(pair_coord));

   srand(2);

   for (long i = 0; i < TESTCOUNT; i++) {
      double baseLat = (double)rand() * 60.0 / RANDMAX;
      pair_coord* x = &mem[i];
      x->lat1 = (baseLat + (double)rand() * 3.0 / RANDMAX - 1.5) * DEG2RAD;
      x->lon1 = ((double)rand() * 3.0 / RANDMAX - 1.5) * DEG2RAD;
      x->lat2 = (baseLat + (double)rand() * 3.0 / RANDMAX - 1.5) * DEG2RAD;
      x->lon2 = ((double)rand() * 3.0 / RANDMAX - 1.5) * DEG2RAD;
   }

   while(1) {

      // set the output pin to HIGH state

      double s = 0;
      for (long i = 0; i < TESTCOUNT; i++) {
         pair_coord* x = &mem[i];
         double d = fai_sphere(x->lat1, x->lon1, x->lat2, x->lon2);
         s += d;
      }

      // set the output pin to LOW state

      s = 0;
      for (long i = 0; i < TESTCOUNT; i++) {
         pair_coord* x = &mem[i];
         double d = wgs84_andoyer(x->lat1, x->lon1, x->lat2, x->lon2);
         s += d;
      }

   }

   return 0;
}