sdfft2du(3F)

NAME
     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
     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
     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
     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.
     LDA - INTEGER.
     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.
     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
     o32fft