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construct_data_2d.c
1 /*
2 * Copyright (c) 2002, 2017 Jens Keiner, Stefan Kunis, Daniel Potts
3 *
4 * This program is free software; you can redistribute it and/or modify it under
5 * the terms of the GNU General Public License as published by the Free Software
6 * Foundation; either version 2 of the License, or (at your option) any later
7 * version.
8 *
9 * This program is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
11 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
12 * details.
13 *
14 * You should have received a copy of the GNU General Public License along with
15 * this program; if not, write to the Free Software Foundation, Inc., 51
16 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
17 */
18
19 #include "config.h"
20
21 #include <stdlib.h>
22 #include <math.h>
23 #ifdef HAVE_COMPLEX_H
24 #include <complex.h>
25 #endif
26
27 #include "nfft3.h"
28
38 static void construct(char * file, int N, int M)
39 {
40 int j,k; /* some variables */
41 double real;
42 nfft_plan my_plan; /* plan for the two dimensional nfft */
43 FILE* fp;
44 FILE* fk;
45 FILE* fi;
46
47 /* initialise my_plan */
48 nfft_init_2d(&my_plan,N,N,M);
49
50 fp=fopen("knots.dat","r");
51
52 for(j=0;j<my_plan.M_total;j++)
53 {
54 fscanf(fp,"%le %le ",&my_plan.x[2*j+0],&my_plan.x[2*j+1]);
55 }
56 fclose(fp);
57
58 fi=fopen("input_f.dat","r");
59 fk=fopen(file,"w");
60
61 for(j=0;j<N;j++)
62 {
63 for(k=0;k<N;k++) {
64 fscanf(fi,"%le ",&real);
65 my_plan.f_hat[(N*j+k)] = real;
66 }
67 }
68
69 if(my_plan.flags & PRE_PSI)
70 nfft_precompute_psi(&my_plan);
71
72 nfft_trafo(&my_plan);
73
74 for(j=0;j<my_plan.M_total;j++)
75 {
76 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]));
77 }
78 fclose(fk);
79 fclose(fi);
80
81 nfft_finalize(&my_plan);
82 }
83
84 int main(int argc, char **argv)
85 {
86 if (argc <= 3) {
87 printf("usage: ./construct_data FILENAME N M\n");
88 return 1;
89 }
90
91 construct(argv[1],atoi(argv[2]),atoi(argv[3]));
92
93 return 1;
94 }
95 /* \} */
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