3.0 API Reference

taylor_nfft.c File Reference

Testing the nfft againt a Taylor expansion based version. More...

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "util.h"
#include "nfft3.h"

Go to the source code of this file.

Data Structures
struct	taylor_plan
Functions
void	taylor_init (taylor_plan *ths, int N, int M, int n, int m)
	Initialisation of a transform plan.
void	taylor_precompute (taylor_plan *ths)
	Precomputation of weights and indices in Taylor expansion.
void	taylor_finalize (taylor_plan *ths)
	Destroys a transform plan.
void	taylor_trafo (taylor_plan *ths)
	Executes a Taylor-NFFT, see equation (1.1) in [Guide], computes fast and approximate by means of a Taylor expansion for j=0,.
void	taylor_time_accuracy (int N, int M, int n, int m, int n_taylor, int m_taylor, unsigned test_accuracy)
	Compares NDFT, NFFT, and Taylor-NFFT.
int	main (int argc, char **argv)

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Detailed Description

Testing the nfft againt a Taylor expansion based version.

Author:

Stefan Kunis

References: Time and memory requirements of the Nonequispaced FFT

Definition in file taylor_nfft.c.

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Function Documentation

void taylor_init (  taylor_plan *  ths, int  N, int  M, int  n, int  m )

Initialisation of a transform plan. ths The pointer to a taylor plan N The multi bandwidth M The number of nodes n The fft length m The order of the Taylor expansion Author: Stefan Kunis Definition at line 37 of file taylor_nfft.c. References FFT_OUT_OF_PLACE, FFTW_INIT, MALLOC_F, MALLOC_F_HAT, MALLOC_X, and nfft_init_guru(). Referenced by taylor_time_accuracy().

void taylor_precompute (  taylor_plan *  ths  )

Precomputation of weights and indices in Taylor expansion. ths The pointer to a taylor plan Author: Stefan Kunis Definition at line 56 of file taylor_nfft.c. References taylor_plan::deltax0, taylor_plan::idx0, nfft_plan::M_total, nfft_plan::n, and nfft_plan::x. Referenced by taylor_time_accuracy().

void taylor_finalize (  taylor_plan *  ths  )

Destroys a transform plan. ths The pointer to a taylor plan Author: Stefan Kunis, Daniel Potts Definition at line 78 of file taylor_nfft.c. References taylor_plan::deltax0, taylor_plan::idx0, and nfft_finalize(). Referenced by taylor_time_accuracy().

void taylor_trafo (  taylor_plan *  ths  )

Executes a Taylor-NFFT, see equation (1.1) in [Guide], computes fast and approximate by means of a Taylor expansion for j=0,. ..,M-1 f[j] = sum_{k in I_N^d} f_hat[k] * exp(-2 (pi) k x[j]) ths The pointer to a taylor plan Author: Stefan Kunis Definition at line 96 of file taylor_nfft.c. References taylor_plan::deltax0, nfft_plan::f, nfft_plan::f_hat, nfft_plan::g1, nfft_plan::g2, taylor_plan::idx0, nfft_plan::m, nfft_plan::M_total, nfft_plan::my_fftw_plan1, nfft_plan::N_total, nfft_plan::n_total, and PI. Referenced by taylor_time_accuracy().

void taylor_time_accuracy (  int  N, int  M, int  n, int  m, int  n_taylor, int  m_taylor, unsigned  test_accuracy )

Compares NDFT, NFFT, and Taylor-NFFT. N The bandwidth N The number of nodes n The FFT-size for the NFFT m The cut-off for window function n_taylor The FFT-size for the Taylor-NFFT m_taylor The order of the Taylor approximation test_accuracy Flag for NDFT computation Author: Stefan Kunis share nodes, input, and output vectors output vector ndft init pseudo random nodes nfft precomputation nfft precomputation init pseudo random Fourier coefficients NDFT NFFT TAYLOR NFFT finalise Definition at line 152 of file taylor_nfft.c. References nfft_plan::f, nfft_plan::f_hat, FFT_OUT_OF_PLACE, FFTW_INIT, nfft_plan::M_total, nfft_plan::N_total, ndft_trafo(), nfft_error_l_infty_complex(), nfft_finalize(), nfft_plan::nfft_flags, nfft_init_guru(), nfft_precompute_one_psi(), nfft_second(), NFFT_SWAP_complex, nfft_trafo(), nfft_vrand_shifted_unit_double(), nfft_vrand_unit_complex(), taylor_plan::p, PRE_FG_PSI, PRE_ONE_PSI, PRE_PHI_HUT, taylor_finalize(), taylor_init(), taylor_precompute(), taylor_trafo(), and nfft_plan::x. Referenced by main().

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