Fast and accurate computation of projected two-point functions

Henry S. Grasshorn Gebhardt, Donghui Jeong

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


We present the two-point function from the fast and accurate spherical Bessel transformation (2-FAST) algorithm1Our code is available at 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 P(k) onto the configuration space, ξlν(r), or spherical harmonic space, Cl(χ,χ′). First, we employ the FFTLog transformation of the power spectrum to divide the calculation into P(k)-dependent coefficients and P(k)-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.

Original languageEnglish (US)
Article number023504
JournalPhysical Review D
Issue number2
StatePublished - Jan 8 2018

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)


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