# Update of spherical Bessel transform: FFTW and OpenMP

## Description

Abstract We present an update of spherical Bessel transform subroutines. The update makes use of the widely available FFTW library for performing necessary fast Fourier transforms. Moreover, the update is prepared for shared memory OpenMP parallelization that is popular on multi-core processors. Furthermore, the updated version uses the module concept to achieve a better control over the memory allocation/deallocation, which also contributes to the performance of the updated package. Title of program: SBT, version number 3 Catalogue Id: AANZ_v3_0 Nature of problem The Fourier transform of a spherically symmetric angular momentum eigen-function leads to the spherical Bessel transform of the corresponding radial function. Radial functions are often given numerically, on a radial grid. Therefore, the direct computation of the spherical Bessel transform would require of order N arithmetical operations for each value of the transform variable, where N is the number of points on the radial grid. At large values of the transform variable, the rapid oscillation o ... Versions of this program held in the CPC repository in Mendeley Data AANZ_v1_0; LSFBTR; 10.1016/0010-4655(83)90126-1 AANZ_v2_0; NumSBT; 10.1016/j.cpc.2008.10.003 AANZ_v3_0; SBT, version number 3; 10.1016/j.cpc.2010.08.024 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)