Awesome

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.