Data structure and functions

The library defines the structure nfft_plan, the most important members are listed in Table 4.1. Moreover, the user functions for the NFFT are collected in Table 4.2. They all have return type void and their first argument is of type nfft_plan*.

Table 4.1: Interesting members of nfft_plan.

Type	Name	Size	Description
int	d	1	Spatial dimension $d$
int*	N	d	Multibandwidth $\ensuremath{\boldsymbol{N}}$
int	N_total	1	Number of coefficients $\vert I_{\ensuremath{\boldsymbol{N}}}\vert$
int	M_total	1	Number of nodes $M$
double complex*	f_hat	$\vert I_{\ensuremath{\boldsymbol{N}}}\vert$	Fourier coefficients $\ensuremath{\boldsymbol{\hat f}}$ or
			adjoint coefficients $\ensuremath{\boldsymbol{\hat h}}$
double complex*	f	$M$	Samples $\ensuremath{\boldsymbol{f}}$
double*	x	$dM$	Sampling set ${\cal X}$

Table 4.2: User functions of the NFFT.

Name	Additional arguments
ndft_trafo
ndft_adjoint
nfft_trafo
nfft_adjoint
nfft_init_1d	int N0, int M
nfft_init_2d	int N0, int N1, int M
nfft_init_3d	int N0, int N1, int N2, int M
nfft_init	int d, int* N, int M
nfft_init_guru	int d, int* N, int M, int* n, int m,
	unsigned nfft_flags, unsigned fftw_flags
nfft_precompute_one_psi
nfft_check
nfft_finalize