Abstract
We present the two-point function from the fast and accurate spherical Bessel transformation (2-FAST) algorithm for a fast and accurate computation of integrals involving one or two spherical Bessel functions. These types of integrals occur when projecting the galaxy power spectrum onto the configuration space, , or spherical harmonic space, . First, we employ the FFTLog transformation of the power spectrum to divide the calculation into -dependent coefficients and -independent integrations of basis functions multiplied by spherical Bessel functions. We find analytical expressions for the latter integrals in terms of special functions, for which recursion provides a fast and accurate evaluation. The algorithm, therefore, circumvents direct integration of highly oscillating spherical Bessel functions.
Our code is available at https://github.com/hsgg/twoFAST.
17 More- Received 15 September 2017
DOI:https://doi.org/10.1103/PhysRevD.97.023504
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