A Fast chi-squared technique for period search of irregularly sampled data

Abstract

A new, computationally and statistically efficient algorithm, the Fast χ2 algorithm (Fχ2), can find a periodic signal with harmonic content in irregularly sampled data with nonuniform errors. The algorithm calculates the minimized χ2 as a function of frequency at the desired number of harmonics, using fast Fourier transforms to provide O(N logN) performance. The code for a reference implementation is provided.