To get a difficult function into a microcontroller:

1) If you are using a high level language that allows FLOAT variable type, it should also have the math routine to do exponents.

2) If you are using Assembler, or cheap compiler, there is another harder way:
Combine scaled integer with a lookup table.

3) Applies to any type of problem: A good starting point is to use a PC spreadsheet to determine the range of inputs and outputs you have, then figure out how to manage them into the device you are using.