Comparing IEEE floats and doubles for equality

Question

What is the best method for comparing IEEE floats and doubles for equality? I have heard of several methods, but I wanted to see what the community thought.

Answer 1

If you are looking for two floats to be equal, then they should be identically equal in my opinion. If you are facing a floating point rounding problem, perhaps a fixed point representation would suit your problem better.

Perhaps I should explain the problem better. In C++, the following code:

#include 

using namespace std;


int main()
{
  float a = 1.0;
  float b = 0.0;

  for(int i=0;i<10;++i)
  {
    b+=0.1;
  }

  if(a != b)
  {
    cout << "Something is wrong" << endl;
  }

  return 1;
}

prints the phrase "Something is wrong". Are you saying that it should?