Fast Fourier Transformation of Two Dimensional Satellite Data functions. More...

#include <grass/config.h>
#include <fftw3.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <grass/gmath.h>
#include <grass/gis.h>

Include dependency graph for fft.c:

Go to the source code of this file.

Macros
#define	c_re(c) ((c)[0])

#define	c_im(c) ((c)[1])

Functions
int	fft2 (int i_sign, double(*data)[2], int NN, int dimc, int dimr)
	Fast Fourier Transform for two-dimensional array. More...

int	fft (int i_sign, double *DATA[2], int NN, int dimc, int dimr)
	Fast Fourier Transform for two-dimensional array. More...

Detailed Description

Fast Fourier Transformation of Two Dimensional Satellite Data functions.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Author: GRASS GIS Development Team

Date: 2001-2006

Definition in file fft.c.

Macro Definition Documentation

◆ c_im

#define c_im ( c ) ((c)[1])

Definition at line 33 of file fft.c.

◆ c_re

#define c_re ( c ) ((c)[0])

Definition at line 32 of file fft.c.

Function Documentation

◆ fft()

int fft	(	int	i_sign,
		double *	DATA[2],
		int	NN,
		int	dimc,
		int	dimr
	)

Fast Fourier Transform for two-dimensional array.

Fast Fourier Transform for two-dimensional array.
<bNote: If passing real data to fft() forward transform (especially when using fft() in a loop), explicitly (re-)initialize the imaginary part to zero (DATA[1][i] = 0.0). Returns 0.

Parameters

[in]	i_sign	Direction of transform -1 is normal, +1 is inverse
[in,out]	DATA	Pointer to complex linear array in row major order containing data and result
[in]	NN	Value of DATA dimension (dimc * dimr)
[in]	dimc	Value of image column dimension (max power of 2)
[in]	dimr	Value of image row dimension (max power of 2)

Returns: int always returns 0

Definition at line 122 of file fft.c.

Referenced by del2g().

◆ fft2()

int fft2	(	int	i_sign,
		double(*)	data[2],
		int	NN,
		int	dimc,
		int	dimr
	)