If I have understood this correctly what you are asking is it there an easy way to find an line of best approxation and then find the max point of that line.

This is really a maths problem and finding the correct Math::* module is a pain as Math::Brent shows the documentation on CPAN is very bad.

PS:Math::Brent from the POD
This is an implementation of Brents method for One-Dimensional minimisation of a function without using derivatives. This algorithm cleverly uses both the Golden Section Search and parabolic interpolation.

Now where is a module that matches a polynomial function to a dataset? Was it Math::Polynimial or is that something different?

PS:Math::Polynomial from the POD
This module implements single variable polynomials using arrays. It also implements some useful functionality when working with polynomials, such as adding, multiplication, etc.

Nope that doesn't help find the polynomial but could be used to find points of inflections.

Think I have got it Math::Bezier (Wow some docs) to map your graph to a curve and then use Math::Brent to find the max value of y.

Hope this helps
UnderMine

Updated Added Math::Polynomial from pod.

Updated Added Math::Beziar