cfft3di,zfft3di(3F) cfft3di,zfft3di(3F)NAME
cfft3di, zfft3di - initialize the coefficient array for complex-to-
complex 3D FFT modules.
SYNOPSYS
FORTRAN SPECIFICATION
subroutine CFFT3DI( n1, n2, n3, coeff )
integer n1, n2, n3
complex coeff((n1+15) + (n2+15) + (n3+15))
subroutine ZFFT3DI( n1, n2, n3, coeff )
integer n1, n2, n3
double complex coeff((n1+15) + (n2+15) + (n3+15))
C SPECIFICATION
#include <fft.h>
complex *cfft3di( int n1, int n2, int n3, complex *coeff);
zomplex *zfft3di( int n1, int n2, int n3, zomplex *coeff);
DESCRIPTION
Initialize the coefficient array which is used in the 3D FFT modules.
This array contains the different twiddle factors and the factorization
of N1,N2 and N3 into prime numbers.
As the FFT modules cfft3d or zfft3d only read the coeff array, it may be
reused as many times as necessary once it has been initialized.
In C, if ptr is NULL, cfft3di or zfft3di returns a pointer to an
allocated buffer.
CFFT3DI should be used to initialize the coefficient array before any
call to CFFT3D
ZFFT3DI should be used to initialize the coefficient array before any
call to ZFFT3D
PARAMETERS
N1 - Integer, the first dimension size of the 3D sequence. Unchanged on
exit.
N2 - Integer, the second dimension size of the 3D sequence. Unchanged on
exit.
N3 Integer, the third dimension size of the 3D sequence. Unchanged on
exit.
COEFF - Array (C or Fortran) or NULL pointer(C).
Example of Calling Sequence
Initializing a coefficient array for complex-to-complex FFTs of size
200x300X125
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cfft3di,zfft3di(3F) cfft3di,zfft3di(3F)
Fortran :
complex coeff((200+15)+(300+15)+(125+15))
call cfft3di( 200, 300, 125, coeff)
C :
#include <fft.h>
complex *coeff;
coeff = cfft3di( 200, 300, 125, NULL);
SEE ALSO
fft, cfft3d, zfft3d
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