[PeterK]

The 64 bit host cannot be perfect, because some calculations depend on the Microsoft compiler.

@Thomas Richter

I made some tests with one of the examples for double rounding from your link above. All Mathlibs that I tested returned the same results.

But I didn't test the other examples yet. Am I doing something wrong in my test code? Try it out.


Update: Yes, the second example (t=s+y) produces indeed a double rounding issue with my mathlibs, but not with the OS mathlibs.

It seems to be exactly the constellation that I already described some years ago in our A1k.org discussion. The results of these special cases are never accurate anyway and the error is only 50% of the least significant bit of huge numbers, nearly the same amount as with the OS mathlibs, but just rounded up, not down.

It already rounds up instead of down, but only at the highest fragment bit sequence where rounding down is still possible and expected. The additional relative error is very low and this sort of double rounding happens quite rarely, so I won't care, because it has more disadvantages to use Double Precision all the time than getting these double rounding errors.