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nfsft.c File Reference

Implementation file for the NFSFT module. More...

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

Go to the source code of this file.

Defines

#define NFSFT_DEFAULT_NFFT_CUTOFF   6
 The default NFFT cutoff parameter.
#define NFSFT_DEFAULT_THRESHOLD   1000
 The default threshold for the FPT.
#define NFSFT_BREAK_EVEN   5
 The break-even bandwidth $N \in \mathbb{N}_0$.

Functions

void c2e (nfsft_plan *plan)
 Converts coefficients $\left(b_k^n\right)_{k=0}^M$ with $M \in \mathbb{N}_0$, $-M \le n \le M$ from a linear combination of Chebyshev polynomials

\[ f(\cos\vartheta) = \sum_{k=0}^{2\lfloor\frac{M}{2}\rfloor} a_k (\sin\vartheta)^{n\;\mathrm{mod}\;2} T_k(\cos\vartheta) \]

to coefficients $\left(c_k^n\right)_{k=0}^M$ matching the representation by complex exponentials

\[ f(\cos\vartheta) = \sum_{k=-M}^{M} c_k \mathrm{e}^{\mathrm{i}k\vartheta} \]

for each order $n=-M,\ldots,M$.

void c2e_transposed (nfsft_plan *plan)
 Transposed version of the function c2e.

Variables

static struct nfsft_wisdom wisdom = {false,0U}
 The global wisdom structure for precomputed data.


Detailed Description

Implementation file for the NFSFT module.

Author:
Jens Keiner

Definition in file nfsft.c.


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