TEST/initialize_d1.c File Reference

Precompute data for the direct1 algorithm. More...

#include "../libftsh.h"

Functions
void	main (int argc, char *argv[])

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Detailed Description

Precompute data for the direct1 algorithm.

This program initializes the direct transform for spherical harmonics, for comparison with "fast" transforms. The direct transform is ordinary dense matrix times vector multiplication. We do however take advantage of the even/odd symmetry about the equator.

Usage: call this routine with 3 command-line arguments: numpts band_limit out_file

• numpts -- the number of latitude points. We construct a gaussian quadrature for this number of points, although other node/weight combinations could be used. In this version, the number of points must be divisible by 2.
• band_limit -- The restriction on the degree of the expansion (n in \(P^m_n\) notation). For gaussian nodes this must be less than numpts.
• out_file -- The name of the file in which to put results of the initialization