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/*--------------------------------*-C-*---------------------------------*
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* Singleton's multivariate complex Fourier transform, computed in
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* place using mixed-radix Fast Fourier Transform algorithm.
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* Called here `fftn' since it does a radix-n FFT on n-dimensional data
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* Copyright(c)1995,97 Mark Olesen <olesen@me.QueensU.CA>
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* Queen's Univ at Kingston (Canada)
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* Permission to use, copy, modify, and distribute this software for
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* any purpose without fee is hereby granted, provided that this
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* entire notice is included in all copies of any software which is
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* or includes a copy or modification of this software and in all
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* copies of the supporting documentation for such software.
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* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR QUEEN'S
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* UNIVERSITY AT KINGSTON MAKES ANY REPRESENTATION OR WARRANTY OF ANY
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* KIND CONCERNING THE MERCHANTABILITY OF THIS SOFTWARE OR ITS
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* FITNESS FOR ANY PARTICULAR PURPOSE.
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* All of which is to say that you can do what you like with this
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* source code provided you don't try to sell it as your own and you
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* include an unaltered copy of this message (including the
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* It is also implicitly understood that bug fixes and improvements
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* should make their way back to the general Internet community so
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* that everyone benefits.
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* Brief overview of parameters:
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* ---------------------------------------------------------------------*
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* Re[]: real value array
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* Im[]: imaginary value array
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* nTotal: total number of complex values
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* nPass: number of elements involved in this pass of transform
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* nSpan: nspan/nPass = number of bytes to increment pointer
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* isign: exponent: +1 = forward -1 = reverse
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* scaling: normalizing constant by which the final result is DIVIDED
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* scaling == -1, normalize by total dimension of the transform
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* scaling < -1, normalize by the square-root of the total dimension
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* Slightly more detailed information:
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* ----------------------------------------------------------------------*
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* void fft_free (void);
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* free-up allocated temporary storage after finished all the Fourier
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* ----------------------------------------------------------------------*
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* int fftn (int ndim, const int dims[], REAL Re[], REAL Im[],
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* int iSign, double scaling);
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* NDIM = the total number dimensions
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* DIMS = a vector of array sizes
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* if NDIM is zero then DIMS must be zero-terminated
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* RE and IM hold the real and imaginary components of the data, and
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* return the resulting real and imaginary Fourier coefficients.
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* Multidimensional data *must* be allocated contiguously. There is
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* no limit on the number of dimensions.
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* ISIGN = the sign of the complex exponential
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* (ie, forward or inverse FFT)
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* the magnitude of ISIGN (normally 1) is used to determine
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* the correct indexing increment (see below).
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* SCALING = normalizing constant by which the final result is DIVIDED
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* if SCALING == -1, normalize by total dimension of the transform
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* if SCALING < -1, normalize by the square-root of the total dimension
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* tri-variate transform with Re[n3][n2][n1], Im[n3][n2][n1]
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* int dims[3] = {n1,n2,n3}
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* fftn (3, dims, Re, Im, 1, scaling);
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* or, using a null terminated dimension list
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* int dims[4] = {n1,n2,n3,0}
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* fftn (0, dims, Re, Im, 1, scaling);
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* ----------------------------------------------------------------------*/
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extern void fft_free (void);
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/* double precision routine */
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extern int fftn (int /* ndim */,
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const int /* dims */[],
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double /* scaling */);
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/* float precision routine */
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extern int fftnf (int /* ndim */,
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const int /* dims */[],
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double /* scaling */);
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/*----------------------- end-of-file (C header) -----------------------*/
added
removed
Lib/FFT/fftn.h
