[AlotOfReading]

Logarithms are interesting because there's hardware to approximate them built into every modern processor as part of floating point. If you can accept the error, you can abuse it to compute logs with a single FMA.

An example of an exp and a log respectively from my personal library of bit hacks:

    bit_cast<float>((int32_t)(fma(12102203.2f, x, 0x3f800000)));

    bit_cast<float>((uint32_t)(-0x3f800000 - 36707.375f*x)) + 7;