Floating point numbers have the highest precision when they're near 0. So if you know a number is going to be near 1, like exp(x) when x is small, then it's bet

Floating point numbers have the highest precision when they're near 0. So if you know a number is going to be near 1, like exp(x) when x is small, then it's better to calculate the offset from 1 rather than the number itself. Programming languages make 'expm1' available for this purpose, which computes exp(x)-1.