test_conv_semi_memo.c File Reference

Example of source code to convolve two real-valued functions defined on the 2-sphere. Uses seminaive algorithms. More...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fftw3.h>
#include "s2kit/FST_semi_memo.h"
#include "s2kit/cospml.h"

Go to the source code of this file.

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

Detailed Description

Example of source code to convolve two real-valued functions defined on the 2-sphere. Uses seminaive algorithms.

Precomputes all necessary data in memory prior to transforming.
Reads in a function and filter from files specified at shell level, and dumps output into a specified file.

Note

Both function and filter must be 4*bw*bw arrays.

Sample call:

test_conv_semi_memo signal_file filter_file output_file bandwidth
test_conv_semi_memo s64.dat     f64.dat     o64.dat     64

In this example, the signal and filter function samples are stored in the files:
s64.dat (signal for bandwidth = 64)
f64.dat (filter for bandwidth = 64)
s128.dat (signal for bandwidth = 128)
f128.dat (filter for bandwidth = 128)
The signal is a "noisy" bump on the sphere, and the filter is a smooth, symmetric bump at the north pole.

The samples for each are stored in "latitude-major" format. I.e.

(theta_0,      phi_0)
(theta_0,      phi_1)
(theta_0,      phi_2)
          ...
(theta_0,      phi_{bw-1})
(theta_1,      phi_0)
(theta_1,      phi_1)
          ...
(theta_{bw-1}, phi_{bw-1})
 
where theta_k = pi*(2*j+1)/(4*bw)
        phi_j = 2*pi*k/(2*bw)

The location of the maximum value in the output file tells us where the bump is.

Definition in file test_conv_semi_memo.c.

Function Documentation

main()

int main	(	int	argc,
		char **	argv
	)

Definition at line 53 of file test_conv_semi_memo.c.