sp_math.h is, as noted at the top of the file, a repackaging of https://github.com/HandmadeMath/HandmadeMath

It is not part of the core library. It is certainly not meant as a reference-level implementation of math functions. It's there so you can write an easing function for a game without pulling in libc. It seems like its existence has offended you. If that's the case...I'm sorry? At every possible point, I note as loudly as possible exactly what that library is. I found your tone extremely dismissive and disrespectful and I don't care to engage with that any more than I already have.