> For Windows, you need to do much more than this: it's not just about handling NaNs and infinities, it's about reimplementing the entire function from scratch to give correctly rounded results. Without correctly-rounded results, there's very little point in having fma.

Would it make sense to only make the function available on non-Windows platforms? As we do for other Unix-only functions in the os module. Maybe even skip more platforms if they provide a broken implementation.

We could implement a test suite in configure to decide if fma() fits our requirements or not.