std::ratio_equal

template <class R1, class R2>
struct ratio_equal : integral_constant<bool, R1::num==R2::num && R1::den==R2::den> {};

// ratio_equal example
#include <iostream>
#include <ratio>

int main ()
{
  typedef std::ratio<1,2> one_half;
  typedef std::ratio<2,4> two_fourths;

  std::cout << "1/2 == 2/4 ? " << std::boolalpha;
  std::cout << std::ratio_equal<one_half,two_fourths>::value << std::endl;

  return 0;
}