[ekelsen]

For those interested in more detail / explanation, the paper below does a good job explaining the basic idea of how this works, but with only a 1st order approximation for the mantissa bits. The first order approximation reduces the calculation of exp to just one multiply and one add - which are often combined into just one instruction on modern processors.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.9.4...