TEST/synthesize_f1.c File Reference

Synthesize (evaluate) using the fast1 algorithm. More...

#include "../libftsh.h"

Defines
#define	DOTIME   1
Functions
int	main (int argc, char *argv[])

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Detailed Description

Synthesize (evaluate) using the fast1 algorithm.

This program does the sythesis (evaluation) portion of the fast transform for spherical harmonics, using the plan created by initialize_f1

This is essentially a demo version, since in a real program one would not want to read/write to files this often.

We only do the Associated Legendre Transform part of the SH transform. To do a full transform, you also need to fourier transform in longitude.

Usage: call this routine with 3 command-line arguments: f1_file coef_file out_file

• f1_file -- The file created by initialize_f1, for the size problem you want
• coef_file -- The file containing the SH coefficients. They must agree with the size determined by band_limit, which is read from f1_file. The ordering is m= 0, 1, -1, 2, -2 ... For a given m, there are (band_limit -abs(m)) REAL values, in binary.
• out_file -- the file in which to put the function values. These are not true function values, because we do not do the fourier transform in longitude. The ordering is m= 0, 1, -1, 2, -2 ... For a given m, there are numpts REAL values, in binary. (numpts is the number of latitude points, read from f1_file.)

OPTIONS:

• set DOTIME to 1 to turn on timing