scfft3dui,dzfft3dui(3F) scfft3dui,dzfft3dui(3F)NAME
scfft3dui, dzfft3dui - initialize the coefficient array for real-to-
complex 3D FFT modules.
SYNOPSYS
FORTRAN SPECIFICATION
subroutine SCFFT3DUI( n1, n2, n3, coeff )
integer n1, n2, n3
real coeff((n1+15) + 2*(n2+15) + 2*(n3+15))
subroutine DZFFT3DUI( n1, n2, n3, coeff )
integer n1, n2, n3
real*8 coeff((n1+15) + 2*(n2+15) + 2*(n3+15))
C SPECIFICATION
#include <fft.h>
float *scfft3dui( int n1, int n2, n3, float *coeff);
double *dzfft3dui( int n1, int n2, n3, double *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 scfft3d or dzfft3d 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, scfft3dui or dzfft3dui returns a pointer to an
allocated buffer.
SCFFT3DUI should be used to initialize the coefficient array before any
call to SCFFT3DU
DZFFT3DUI should be used to initialize the coefficient array before any
call to DZFFT3DU
PARAMETERS
N1 - Integer. Specifies the size of the first dimension of the 3D
sequence to be transformed. Unchanged on exit.
N2 - Integer. Specifies the size of the second dimension of the 3D
sequence to be transformed. Unchanged on exit.
N3 - Integer. Specifies the size of the third dimension of the 3D
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 real-to-complex FFTs of size 200 x
300 x 125.
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scfft3dui,dzfft3dui(3F) scfft3dui,dzfft3dui(3F)
Fortran :
real coeff((200+15)+2*(300+15)+2*(125+15))
call scfft3dui( 200, 300, 125, coeff)
C :
#include <fft.h>
float *coeff;
coeff = scfft3dui( 200, 300, 125, NULL);
SEE ALSO
fft, scfft3du, dzfft3du
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