cfft2di,zfft2di(3F)					   cfft2di,zfft2di(3F)

NAME    [Toc]    [Back]

     cfft2di, zfft2di -	initialize the coefficient array for complex-tocomplex
 2D	FFT modules.

SYNOPSYS    [Toc]    [Back]

     FORTRAN SPECIFICATION
     subroutine	CFFT2DI( n1, n2, coeff )
     integer		      n1, n2
     complex		 coeff((n1+15) + (n2+15))

     subroutine	ZFFT2DI( n1, n2, coeff )
     integer		      n1, n2
     double complex	 coeff((n1+15) + (n2+15))

     C SPECIFICATION
     #include <fft.h>
     complex *cfft2di( int n1, int n2, complex *coeff);

     zomplex *zfft2di( int n1, int n2, zomplex *coeff);

DESCRIPTION    [Toc]    [Back]

     Initialize	the coefficient	array which is used in the 2D FFT modules.
     This array	contains the different twiddle factors and the factorization
     of	N1 and N2 into prime numbers.
     As	the FFT	modules	cfft2d or zfft2d only read the coeff array, it may be
     reused as long as necessary once it has been initialized.

     In	C, if ptr is NULL, cfft2di or zfft2di returns a	pointer	to an
     allocated buffer.

     CFFT2DI should be used to initialize the coefficient array	before any
     call to CFFT2D
     ZFFT2DI should be used to initialize the coefficient array	before any
     call to ZFFT2D

PARAMETERS    [Toc]    [Back]

     N1	- Integer, the first dimension size of the 2D sequence.
     Unchanged on exit.

     N2	- Integer, the second dimension	size of	the 2D 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 200
     x 300.

     Fortran :
	  complex coeff((200+15)+(300+15))
	  call cfft2di(	200, 300, coeff)



									Page 1






cfft2di,zfft2di(3F)					   cfft2di,zfft2di(3F)



     C :
	  #include <fft.h>
	  complex *coeff;
	  coeff	= cfft2di( 200,	300, NULL);

SEE ALSO    [Toc]    [Back]

	  fft, cfft2d, zfft2d


									PPPPaaaaggggeeee 2222