Ticket #11102: test.cpp

/*
  Compiled with:
  > gcc -I<BOOST_HOME>/include -c -g -o test.o test.cpp
  > gcc -o test test.o -lgmp -lstdc++
  
  Output:
  > ./test
  Input: 0.840188, 0.394383, 0.783099
  Output A: 0
  Input: 0.79844, 0.911647, 0.197551
  Output B: 1.25764e-58
*/

#include <iostream>
#include <cstdlib>
#include <boost/multiprecision/gmp.hpp>

namespace b_mp = boost::multiprecision;
typedef b_mp::number<b_mp::gmp_float<0>, b_mp::et_off> test_float_type;

// get random value between 0 and 1
void set_rand(test_float_type* v, bool with_division) {
  for (int i = 0; i < 3; i++) {
    v[i] = with_division ?
      test_float_type(double(std::rand()) / double(RAND_MAX)) :
      test_float_type(std::rand()) / test_float_type(RAND_MAX);
  }
}

// test distributive property
int main() {
  test_float_type v[3], a1, a2;

  set_rand(v, true);
  std::cerr << "Input: " << v[0] << ", " << v[1] << ", " << v[2] << std::endl;
  a1 = v[0] * v[1] + v[0] * v[2];
  a2 = v[0] * (v[1] + v[2]);
  std::cerr << "Output A: " << a1 - a2 << std::endl;

  set_rand(v, false);
  std::cerr << "Input: " << v[0] << ", " << v[1] << ", " << v[2] << std::endl;
  a1 = v[0] * v[1] + v[0] * v[2];
  a2 = v[0] * (v[1] + v[2]);
  std::cerr << "Output B: " << a1 - a2 << std::endl;

  return 0;
}