#include <math.h>
#include <stdlib.h>
#include "util.h"
#include "nfft3.h"
Functions | |
int | mpolar_grid (int T, int R, double *x, double *w) |
Generates the points ![]() ![]() ![]() ![]() | |
int | mpolar_dft (fftw_complex *f_hat, int NN, fftw_complex *f, int T, int R, int m) |
discrete mpolar FFT | |
int | mpolar_fft (fftw_complex *f_hat, int NN, fftw_complex *f, int T, int R, int m) |
NFFT-based mpolar FFT. | |
int | inverse_mpolar_fft (fftw_complex *f, int T, int R, fftw_complex *f_hat, int NN, int max_i, int m) |
inverse NFFT-based mpolar FFT | |
int | comparison_fft (FILE *fp, int N, int T, int R) |
Comparison of the FFTW, mpolar FFT, and inverse mpolar FFT. | |
int | main (int argc, char **argv) |
test program for various parameters | |
Variables | |
double | GLOBAL_elapsed_time |
Computes the NFFT-based polar FFT and its inverse on a modified polar grid for various parameters.
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inverse NFFT-based mpolar FFT < index for nodes and freqencies < plan for the nfft-2D < plan for the inverse nfft < knots and associated weights < index for iterations < number of knots < oversampling factor sigma=2 < oversampling factor sigma=2 init two dimensional NFFT plan init two dimensional infft plan init nodes, given samples and weights precompute psi, the entries of the matrix B initialise damping factors initialise some guess f_hat_0 solve the system copy result finalise the plans and free the variables |
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test program for various parameters < mpolar FFT size NxN < number of directions/offsets < number of knots of mpolar grid < knots and associated weights < number of iterations Hence, comparison of the FFTW, mpolar FFT, and inverse mpolar FFT generate knots of mpolar grid load data direct mpolar FFT Test of the mpolar FFT with different m fast mpolar FFT compute error of fast mpolar FFT Test of the inverse mpolar FFT for different m in dependece of the iteration number inverse mpolar FFT compute maximum relativ error free the variables |
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discrete mpolar FFT < index for nodes and freqencies < plan for the nfft-2D < knots and associated weights < number of knots < oversampling factor sigma=2 < oversampling factor sigma=2 init two dimensional NFFT plan init nodes from mpolar grid init Fourier coefficients from given image NDFT-2D copy result finalise the plans and free the variables |
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NFFT-based mpolar FFT. < index for nodes and freqencies < plan for the nfft-2D < knots and associated weights < number of knots < oversampling factor sigma=2 < oversampling factor sigma=2 init two dimensional NFFT plan init nodes from mpolar grid precompute psi, the entries of the matrix B init Fourier coefficients from given image NFFT-2D copy result finalise the plans and free the variables |
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Generates the points We add more concentric circles to the polar grid and exclude those nodes not located in the unit square, i.e.,
with count the knots normalize the weights return the number of knots |