nifty-ls evaluates the Lomb-Scargle periodogram very quickly and accurately. The Lomb-Scargle periodogram, used for identifying periodicity in irregularly-spaced observations, is useful but computationally expensive. However, when it is phrased mathematically as a pair of non-uniform FFTs (NUFFTs), FINUFFT (ascl:2412.007), which is really fast, can be leveraged to improve performance. It also enables GPU (CUDA) support and is several orders of magnitude more accurate than Astropy's (ascl:1304.002) Lomb Scargle with default settings.

FINUFFT (Flatiron Institute Nonuniform Fast Fourier Transform) computes the three standard types of nonuniform FFT to a specified precision, in one, two, or three dimensions. It can be run on a multi-core shared-memory machine or on a GPU. It is extremely fast and has very simple interfaces to most major numerical languages (such as C/C++, Fortran, MATLAB, octave, Python, and Julia). FINUFFT also provides more advanced (vectorized and “guru”) interfaces that allow multiple strength vectors and the reuse of FFT plans.