Fast calculation of the Lomb-Scargle periodogram using nonequispaced fast Fourier transforms

We present a code for the fast computation of the Lomb-Scargle periodogram that uses nonequispaced fast Fourier transforms (FFTs). The computation time has the classical O(Nlog N) behaviour of FFTs, but is shorter by about one order of magnitude than the “classical” fast algorithm by Press and Rybicki, and is about five times shorter that the best GPU-based implementations of the usual O(N2) algorithm. This performance is achieved without sacrificing accuracy, as revealed by comparing the computations done with our FFT-based algorithm and a naïve one.