NFFT: NSFFT - Nonequispaced sparse FFT

NFFT 3.4.1

Direct and fast computation of the nonequispaced FFT on the hyperbolic cross. More...

Data Structures
struct	nsfft_plan
	data structure for an NSFFT (nonequispaced sparse fast Fourier transform) plan with double precision More...

Macros
#define	NSDFT (1U<< 12)

Functions
void	nsfft_trafo (nsfft_plan *ths)

void	nsfft_adjoint (nsfft_plan *ths)

void	nsfft_cp (nsfft_plan ths, nfft_plan ths_nfft)

void	nsfft_init_random_nodes_coeffs (nsfft_plan *ths)

void	nsfft_init (nsfft_plan *ths, int d, int J, int M, int m, unsigned flags)

void	nsfft_finalize (nsfft_plan *ths)

Detailed Description

Direct and fast computation of the nonequispaced FFT on the hyperbolic cross.

Macro Definition Documentation

#define NSDFT (1U<< 12)

If this flag is set, the member index_sparse_to_full is (de)allocated and initialised for the use in the routine nsfft_direct_trafo and nsdft_adjoint.

See Also: nsfft_init

Author: Stefan Kunis

Definition at line 476 of file nfft3.h.

Function Documentation

void nsfft_trafo ( nsfft_plan * ths )

Executes an NSFFT, computes fast and approximate for $j=0,\dots,M-1$ :

$f_j = \sum_{k\in H_N^d}\hat f_k {\rm e}^{-2\pi{\rm\scriptsize i}k x_j}$

ths The pointer to a nsfft plan

Author: Markus Fenn, Stefan Kunis

Definition at line 1541 of file nsfft.c.

References nsfft_plan::d.

void nsfft_adjoint ( nsfft_plan * ths )

Executes an adjoint NSFFT, computes fast and approximate for $k\in H_N^d$ :

$\hat f_k = \sum_{j=0,\dots,M-1} f_j {\rm e}^{+2\pi{\rm\scriptsize i}k x_j}$

ths The pointer to a nsfft plan

Author: Stefan Kunis

Definition at line 1549 of file nsfft.c.

References nsfft_plan::d.

void nsfft_cp	(	nsfft_plan *	ths,
		nfft_plan *	ths_nfft
	)

Copy coefficients from nsfft plan to a nfft plan.

ths Pointers to a nsfft plan and to a nfft plan

Author: Markus Fenn, Stefan Kunis

Definition at line 599 of file nsfft.c.

References nsfft_plan::act_nfft_plan, nsfft_plan::d, nfft_plan::f_hat, nsfft_plan::f_hat, nsfft_plan::index_sparse_to_full, nsfft_plan::M_total, nfft_plan::N_total, nsfft_plan::N_total, and nfft_plan::x.

void nsfft_init_random_nodes_coeffs ( nsfft_plan * ths )

Initialisation of pseudo random nodes and coefficients.

ths The pointer to a nsfft plan

Author: Markus Fenn, Stefan Kunis

Definition at line 723 of file nsfft.c.

References nsfft_plan::act_nfft_plan, nsfft_plan::d, nsfft_plan::f_hat, nsfft_plan::M_total, nsfft_plan::N_total, nfft_vrand_shifted_unit_double(), nfft_vrand_unit_complex(), nfft_plan::x, nsfft_plan::x_021, and nsfft_plan::x_transposed.

void nsfft_init	(	nsfft_plan *	ths,
		int	d,
		int	J,
		int	M,
		int	m,
		unsigned	flags
	)

Initialisation of a transform plan.

ths The pointer to a nsfft plan
d The dimension
J The problem size
M The number of nodes
m nfft cut-off parameter
flags

Author: Markus Fenn, Stefan Kunis

Definition at line 1778 of file nsfft.c.

References UNUSED.

void nsfft_finalize ( nsfft_plan * ths )

Destroys a transform plan.

ths The pointer to a nsfft plan

Author: Markus Fenn, Stefan Kunis

Definition at line 1885 of file nsfft.c.

References nsfft_plan::d.