  Though Fourier Transforms (FTs) are a common technique for finding
correlation functions, they are not typically used in computations of the
anisotropy of the two-point correlation function (2PCF) about the line of sight
in wide-angle surveys because the line-of-sight direction is not constant on
the Cartesian grid. Here we show how FTs can be used to compute the multipole
moments of the anisotropic 2PCF. We also show how FTs can be used to accelerate
the 3PCF algorithm of Slepian & Eisenstein (2015). In both cases, these FT
methods allow one to avoid the computational cost of pair counting, which
scales as the square of the number density of objects in the survey. With the
upcoming large datasets of DESI, Euclid, and LSST, FT techniques will therefore
offer an important complement to simple pair or triplet counts.
