cfftm1di,zfftm1di(3F) cfftm1di,zfftm1di(3F)NAME
cfftm1di, zfftm1di - initialize the coefficient array for complex-to-
complex Multiple 1D FFT modules.
SYNOPSYS
FORTRAN SPECIFICATION
subroutine CFFTM1DI( n, coeff )
integer n
complex coeff(n+15)
subroutine ZFFTM1DI( n, coeff )
integer n
double complex coeff(n+15)
C SPECIFICATION
#include <fft.h>
complex *cfftm1di( int n, complex *coeff);
zomplex *zfftm1di( int n, zomplex *coeff);
DESCRIPTION
Initialize the coefficient array which is used in the Multiple 1D FFT
modules. This array contains the different twiddle factors and the
factorization of N into prime numbers.
As the FFT modules cfftm1d or zfftm1d only read the coeff array, it may
be reused as long as necessary once it has been initialized.
In C, if ptr is NULL, cfftm1di or zfftm1di returns a pointer to an
allocated buffer.
CFFTM1DI should be used to initialize the coefficient array before any
call to CFFTM1D
ZFFTM1DI should be used to initialize the coefficient array before any
call to ZFFTM1D
PARAMETERS
N - Integer. Specifies the length of the sequence to be transformed.
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 200.
Fortran :
complex coeff(200+15)
call cfftm1di( 200, coeff)
C :
#include <fft.h>
complex *coeff;
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cfftm1di,zfftm1di(3F) cfftm1di,zfftm1di(3F)
coeff = cfftm1di( 200, NULL);
SEE ALSO
fft, cfftm1d, zfftm1d
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