TEST/assess_d1.c File Reference

Assess the performance of the direct1 algorithm. More...

#include "../libftsh.h"

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

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Detailed Description

Assess the performance of the direct1 algorithm.

This program does an assessment of the direct transform for spherical harmonics, using the plan created by initialize_d1

We 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.