This is a set of branch-free, table-free implementations of the math functions in <math.h>.

All of the code is public domain - if you like, you can copy out the sin implementation if that's all you need.

These functions differ slightly from the C standard library by design - to stay fast, they don't do range checking or follow C's precision requirements. Think of these routines more as "decent approximations", for when you know the particular input domain and you have leeway with the output. Video games are a good use case.

These functions stick to the C API, but the library doesn't implement all of math.h - notable exclusions are machine-related functions (e.g. fma, nextafter), precision-related functions (e.g. expm1), complex numbers, and tgamma/lgamma. The standard elementary functions that you would expect are included, as well as hyperbolic trig.

• atan2 is highly discontinuous, so a truly branch-free implementation of this routine is likely impossible.

I want this library to be easy to use, so no attribution is necessary.

• The sin algorithm was originally conceived by an anonymous user on a now-unavailable programming forum.
• round, sqrt, rsqrt, and log are all of dubious origin.