sfft2du,dfft2du(3F)					   sfft2du,dfft2du(3F)

NAME    [Toc]    [Back]

     dfft2du, sfft2du -	2D Real	to Complex Fast	Fourier	Transform.

FORTRAN	SPECIFICATION
     subroutine	DFFT2DU( job, n1, n2, sequence,	lda, workspace )
     integer		 job, n1, n2, lda
     double precision	 sequence(lda,*), workspace(*)

     subroutine	SFFT2DU( job, n1, n2, sequence,	lda, workspace )
     integer		 job, n1, n2, lda
     real		 sequence(lda,*), workspace(*)

C SPECIFICATION    [Toc]    [Back]

     int	dfft2du( int job, int n1, int n2,
			 double	*sequence, int lda,
			 double	*workspace)

     int	sfft2du( int job, int n1, int n2,
			 float	*sequence, int lda,
			 float	*workspace)

DESCRIPTION    [Toc]    [Back]

     DFFT2DU and SFFT2DU compute the 2 dimensional complex Fourier transform
     of	a real periodic	sequence.

     NOTE: These routines are provided only for	compatibility with previous
     releases of complib.

PARAMETERS    [Toc]    [Back]

     JOB - INTEGER
     On	entry specifies	whether	to perform a forward or	backward Fast Fourier
     Transform:
	 JOB = -1,  forward FFT
	 JOB =	1,  backward FFT Unchanged on exit.

     N1	- INTEGER.
     On	entry, N1 specifies the	number of elements in the first	dimension of
     the sequence.  Unchanged on exit.

     N2	- INTEGER.
     On	entry, N2 specifies the	number of elements in the second dimension of
     the sequence.  Unchanged on exit.

     SEQUENCE -	Array.
     Array of DIMENSION	( LDA, n2 ).  Array containing the (lda*n2) elements
     for the FFT.  On exit, SEQUENCE is	overwritten by the 2D transform.





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sfft2du,dfft2du(3F)					   sfft2du,dfft2du(3F)



     LDA - INTEGER.    [Toc]    [Back]
     On	entry, LDA specifies the first dimension of the	array SEQUENCE as
     declared in the calling (sub)program. LDA must be at least	max( 1,
     2*((N1+2)/2) ).  Unchanged	on exit.

     WORKSPACE - Array.    [Toc]    [Back]
     Array of dimension	at least (N1+15) + 2*(N2+15).  Array containing	the
     Sines/Cosines and factorization of	N1 and N2.  WORKSPACE needs to be
     initialized by a call to sfft2dui or dfft2dui.

SEE ALSO    [Toc]    [Back]

     o32fft


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