Feature or enhancement

Proposal:

I will first post here because I don't want to flood DPO with a controversial thread. I didn't dig much in the issues so it might have already been discussed a bit more in detail elsewhere.

There are some functions in math.h that we don't export in math as some are useless for Python or just forgotten. We recently added isnormal and issubnormal but the following are missing:

scalbn

It's only useful if FLT_RADIX != 2. Python only supports FLT_RADIX = 2 or 16 but I don't know how many systems have FLT_RADIX = 16. So I don't think we need it for now. logb also depends on FLT_RADIX but I think we can ignore it if we don't add scalbn.

DECISION: let's not add it as numpy doesn't have it and it has a confusing name (at least to me).

fdim

This one could be useful to handle possible signed zeros when doing fp artihmetic. Similarly, math currently lacks fmax and fmin which could useful if we support IEC 60559 because max(nan, inf) == nan and max(inf, nan) == inf which is incorrect (in both cases fmax would have returned inf on such systems).

DECISION: numpy has fmax and fmin and treat the NaNs correctly, but not fdim. For now, let's not add it.

remquo

This one is useful for implementing