scfft3dui,dzfft3dui(3F)				       scfft3dui,dzfft3dui(3F)

NAME    [Toc]    [Back]

     scfft3dui,	dzfft3dui - initialize the coefficient array for real-tocomplex
 3D	FFT modules.

SYNOPSYS    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

	  fft, scfft3du, dzfft3du


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