construct_data_2d.c
/*
* Copyright (c) 2002, 2017 Jens Keiner, Stefan Kunis, Daniel Potts
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option) any later
* version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "config.h"
#include <stdlib.h>
#include <math.h>
#ifdef HAVE_COMPLEX_H
#include <complex.h>
#endif
#include "nfft3.h"
static void construct(char * file, int N, int M)
{
int j,k; /* some variables */
double real;
nfft_plan my_plan; /* plan for the two dimensional nfft */
FILE* fp;
FILE* fk;
FILE* fi;
/* initialise my_plan */
nfft_init_2d(&my_plan,N,N,M);
fp=fopen("knots.dat","r");
for(j=0;j<my_plan.M_total;j++)
{
fscanf(fp,"%le %le ",&my_plan.x[2*j+0],&my_plan.x[2*j+1]);
}
fclose(fp);
fi=fopen("input_f.dat","r");
fk=fopen(file,"w");
for(j=0;j<N;j++)
{
for(k=0;k<N;k++) {
fscanf(fi,"%le ",&real);
my_plan.f_hat[(N*j+k)] = real;
}
}
if(my_plan.flags & PRE_PSI)
nfft_precompute_psi(&my_plan);
nfft_trafo(&my_plan);
for(j=0;j<my_plan.M_total;j++)
{
fprintf(fk,"%le %le %le %le\n",my_plan.x[2*j+0],my_plan.x[2*j+1],creal(my_plan.f[j]),cimag(my_plan.f[j]));
}
fclose(fk);
fclose(fi);
nfft_finalize(&my_plan);
}
int main(int argc, char **argv)
{
if (argc <= 3) {
printf("usage: ./construct_data FILENAME N M\n");
return 1;
}
construct(argv[1],atoi(argv[2]),atoi(argv[3]));
return 1;
}
/* \} */
nfft_plan::f_hat
fftw_complex * f_hat
Fourier coefficients.
Definition: nfft3.h:192
nfft_init_2d
void nfft_init_2d(nfft_plan *ths, int N1, int N2, int M)
construct
static void construct(char *file, int N, int M)
construct makes an 2d-nfft
Definition: construct_data_2d.c:38
nfft_plan::f
fftw_complex * f
Samples.
Definition: nfft3.h:192
nfft_precompute_psi
void nfft_precompute_psi(nfft_plan *ths)
nfft_plan
data structure for an NFFT (nonequispaced fast Fourier transform) plan with double precision ...
Definition: nfft3.h:192
nfft_plan::M_total
NFFT_INT M_total
Total number of samples.
Definition: nfft3.h:192
PRE_PSI
#define PRE_PSI
Definition: nfft3.h:197
nfft_trafo
void nfft_trafo(nfft_plan *ths)
nfft_finalize
void nfft_finalize(nfft_plan *ths)
nfft3.h
Header file for the nfft3 library.
nfft_plan::x
double * x
Nodes in time/spatial domain, size is doubles.
Definition: nfft3.h:192
nfft_plan::flags
unsigned flags
Flags for precomputation, (de)allocation, and FFTW usage, default setting is PRE_PHI_HUT | PRE_PSI | ...
Definition: nfft3.h:192