TEST/assess_f1.c File Reference

Assess the performance of the fast1 algorithm. More...

#include "../libftsh.h"

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

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Detailed Description

Assess the performance of the fast1 algorithm.

This program does an assessment of the fast transform for spherical harmonics, using the plan created by initialize_f1

We determine the number of coefficients in the compressed representation and time the synthesis and analysis transforms for each individual order. Note that totalling the time for each order tends to overestimate the time for the total tranform, for a reason not clear.

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 iterations out_file

• f1_file -- The file created by initialize_f1, for the size problem you want
• iterations -- the number of iterations to do >0. On small problems our timing routine is not precise enough, and will tell us most things take 0 time. To compensate we time some number of iterations of the same process and divide by the number of iterations. This parameter sets the number of iterations for the m==0 case. For other m, we increase the number of iteration to compensate for the smaller problem size
• out_file -- the file in which to put the results We first output global results, in lines beginning with # (so gnuplot can ignore them). Then we give the main data in the form:

   order  coefficient_count  synthesis_time analysis_time

  This column format can then be plotted