Fits a set of known exponential components to a dataset

Decomposes a function g(t) as g(t)=sum_jA_jexp(iw_jt), where the frequencies w_j are already known. Namely, makes a least-squares fit.

signal {numpy.ndarray} -- the signal g(t) to be fit times {numpy.ndarray} -- t values of the signal frequencies {numpy.ndarray} -- known frequencies w_j

amplitudes {numpy.ndarray} -- the found amplitudes A_j