Plus.....I like to repeat that if the linear interpolation (not extrapolation) not precise enough between the known data points then all you need to add is more known data points!! I suspect that for each doubling of the number of known data points that you reduce the errors in the linear iterpolation to less than a third.

Another thing to keep in mind is that the math to perform the linear interpolation is easy to code up, even if you have to do it in assembly language, because it can be done with fixed point numbers.

There is a big likely hood that the math to perform a real time computation of a curve fit needs to be either a double float (see Kai's comment) or would need to use fixed point out to 64 bits. Neither represent something that is easy to implement on a microcontroller.

Michael Karas