sdfft3du(3F)

NAME
     dfft3du, sfft3du - 3D Real to Complex Fast Fourier Transform.

FORTRAN SPECIFICATION
     subroutine DFFT3DU( job, n1, n2, n3, sequence, ld1, ld2, workspace )
     integer             job, n1, n2, n3, ld1, ld2
     double precision    sequence(ld1,ld2,*), workspace(*)

     subroutine SFFT3DU( job, n1, n2, n3, sequence, ld1, ld2, workspace )
     integer             job, n1, n2, n3, ld1, ld2
     real                sequence(ld1,ld2,*), workspace(*)

     C SPECIFICATION
     int        dfft3du( int job, int n1, int n2, int n3,
                         double *sequence, int ld1, int ld2,
                         double *workspace)

     int        sfft3du( int job, int n1, int n2, int n3,
                         float  *sequence, int ld1, int ld2,
                         float  *workspace)


DESCRIPTION
     DFFT3DU and SFFT3DU compute the 3 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.

     N3 - INTEGER.
     On entry, N3 specifies the number of elements in the third dimension of
     the sequence.  Unchanged on exit.

     SEQUENCE - Array.
     Array of DIMENSION ( LD1, LD2, n3 ).  Array containing the (ld1*ld2*n3)
     elements for the FFT.  On exit, SEQUENCE is overwritten by the 3D
     transform.
     LD1 - INTEGER.
     On entry, LD1 specifies the first dimension of the array SEQUENCE as
     declared in the calling (sub)program. LD1 must be at least max( 1,
     2*((n1+2)/2) ).  Unchanged on exit.

     LD2 - INTEGER.
     On entry, LD2 specifies the second dimension of the array SEQUENCE as
     declared in the calling (sub)program. LD2 must be at least max( 1, n2 ).
     Unchanged on exit.

     WORKSPACE - Array.
     Array of dimension at least (N1+15) + 2*(N2+15) + 2*(N3+15).  Array
     containing the Sines/Cosines and factorization of N1, N2 and N3.
     WORKSPACE needs to be initialized by a call to sfft3dui or dfft3dui.


SEE ALSO
     o32fft