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/*****************************************************************************
** FILE IDENTIFICATION
**
** Name: fourier.h
** Purpose: Header for Fourier transform functions
** Programmer: Kevin Rosenberg
** Date Started: Dec 2000
**
** This is part of the CTSim program
** Copyright (c) 1983-2001 Kevin Rosenberg
**
** $Id: fourier.h 7939 2003-10-05 05:47:22Z kevin $
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License (version 2) as
** published by the Free Software Foundation.
**
** 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
******************************************************************************/
#include <complex>
#ifdef HAVE_FFTW
#include <fftw3.h>
#endif
class ImageFile;
class Fourier {
public:
static void shuffleFourierToNaturalOrder (ImageFile& im);
static void shuffleNaturalToFourierOrder (ImageFile& im);
#ifdef HAVE_FFTW
static void shuffleFourierToNaturalOrder (fftw_complex* pc, const int n);
static void shuffleNaturalToFourierOrder (fftw_complex* pc, const int n);
#endif
// Odd Number of Points
// Natural Frequency Order: -(n-1)/2...-1,0,1...(n-1)/2
// Fourier Frequency Order: 0, 1..(n-1)/2,-(n-1)/2...-1
// Even Number of Points
// Natural Frequency Order: -n/2...-1,0,1...((n/2)-1)
// Fourier Frequency Order: 0,1...((n/2)-1),-n/2...-1
template<class T>
static void shuffleNaturalToFourierOrder (T* pVector, const int n)
{
T* pTemp = new T [n];
int i;
if (isOdd(n)) { // Odd
int iHalfN = (n - 1) / 2;
pTemp[0] = pVector[iHalfN];
for (i = 0; i < iHalfN; i++)
pTemp[i + 1] = pVector[i + 1 + iHalfN];
for (i = 0; i < iHalfN; i++)
pTemp[i + iHalfN + 1] = pVector[i];
} else { // Even
int iHalfN = n / 2;
pTemp[0] = pVector[iHalfN];
for (i = 0; i < iHalfN - 1; i++)
pTemp[i + 1] = pVector[i + iHalfN + 1];
for (i = 0; i < iHalfN; i++)
pTemp[i + iHalfN] = pVector[i];
}
for (i = 0; i < n; i++)
pVector[i] = pTemp[i];
delete pTemp;
}
template<class T>
static void shuffleFourierToNaturalOrder (T* pVector, const int n)
{
T* pTemp = new T [n];
int i;
if (isOdd(n)) { // Odd
int iHalfN = (n - 1) / 2;
pTemp[iHalfN] = pVector[0];
for (i = 0; i < iHalfN; i++)
pTemp[i + 1 + iHalfN] = pVector[i + 1];
for (i = 0; i < iHalfN; i++)
pTemp[i] = pVector[i + iHalfN + 1];
} else { // Even
int iHalfN = n / 2;
pTemp[iHalfN] = pVector[0];
for (i = 0; i < iHalfN; i++)
pTemp[i] = pVector[i + iHalfN];
for (i = 0; i < iHalfN - 1; i++)
pTemp[i + iHalfN + 1] = pVector[i+1];
}
for (i = 0; i < n; i++)
pVector[i] = pTemp[i];
delete pTemp;
}
#if 0
static void shuffleNaturalToFourierOrder (float* pdVector, const int n);
static void shuffleNaturalToFourierOrder (double* pdVector, const int n);
static void shuffleNaturalToFourierOrder (std::complex<double>* pdVector, const int n);
static void shuffleFourierToNaturalOrder (float* pdVector, const int n);
static void shuffleFourierToNaturalOrder (double* pdVector, const int n);
static void shuffleFourierToNaturalOrder (std::complex<double>* pdVector, const int n);
#endif
};
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