> Because what's going to happen two years down the road when you need to get that code working on a different platform.

And what happens when the different platform handles overflow differently? Or has non-IEEE floats? Or breaks whatever assumption the C standard already makes?

Here's the thing: C is already built on assumptions, which might or might not hold for a specific platform.

Choosing which assumptions we hold true is a pragmatic choice that must be done. C does it, and does it consciously - but it doesn't mean that it nails every choice.

If you're in a situation where you need specific implementation details of floating point arithmetic, then may the devil have mercy on your soul, because god certainly won't.

Wouldn't debugging / testability imply this is a fairly large proportion of programs? Having a calculation give different results on different hardware would make testing difficult: http://yosefk.com/blog/consistency-how-to-defeat-the-purpose...

Your own link explains how easy it is to get different results even on the same hardware depending on compiler flags.