fastapprox
Approximate and vectorized versions of common mathematical functions
The easiest way to include this in your projects is via the one big standalone header file which works with both C and C++.
Current functions:
- exponential, logarithm, and power
- lgamma and digamma
- cosh, sinh, tanh
- cos, sin, tan
- sigmoid and erf
- Lambert W
There's a Mathematica notebook which helps explain the techniques.