CFFT3D (3sciport)

Applies a three dimensional Fast Fourier Transform (FFT)

SYNOPSIS

  Call CFFT3D( isign, n1, n2, n3, scale, x, inc1x, inc2x, inc3x,
               y, inc1y, inc2y, inc3y, table, ntable, work, nwork )

ARGUMENTS

  isign           Integer.
                  Specifies whether to initialize the coefficient table,
                  perform a forward FFT, perform an inverse FFT, or activate
                  an escape mechanism. Legitimate values for isign are:

                  0  initialize table,
                  +1 compute a  forward transform, and
                  -1 compute an inverse transform.

                  If isign is equal to '80FF0FF0FF0FF0FF'X, then free the
                  CXML structure overlaying table.

  n1              Integer.
                  The order of the FFT in the first dimension.

  n2              Integer.
                  The order of the FFT in the second dimension.

  n3              Integer.
                  The order of the FFT in the third dimension.

  scale           Real.
                  Each element of the complex output vector y is multipled by
                  scale after the FFT is performed.

  x               Complex matrix.
                  The complex input matrix to be Fourier transformed in three
                  dimensions.

  inc1x           Integer.
                  The increment between elements within each vector in the
                  first dimension of matrix x.

  inc2x           Integer.
                  The increment between elements within each vector in the
                  second dimension of matrix x.

  inc3x           Integer.
                  The increment between elements within each vector in the
                  third dimension of matrix x.

  y               Complex matrix.
                  The complex output matrix. If the output matrix overlays
                  the input matrix, an in-place FFT is performed.

  inc1y           Integer.
                  The increment between elements within each vector in the
                  first dimension of matrix y.

  inc2y           Integer.
                  The increment between elements within each vector in the
                  second dimension of matrix y.

  inc3y           Integer.
                  The increment between elements within each vector in the
                  third dimension of matrix y.

  table           Real vector.
                  A vector of constants used by the FFT algorithm. The table
                  is written only when isign is zero. Only the first 34
                  locations are used by the SCIPORT implementation.

  ntable          Integer.
                  The length of the table vector. ntable must be at least 34.

  work            Real vector.
                  A vestigial argument ignored by the SCIPORT implementation.

  nwork           Integer.
                  A vestigial argument ignored by the SCIPORT implementation.

DESCRIPTION

  CFFT3D computes a three dimensional Fourier Transform using the complex
  data matrix x and the coefficient vector table as inputs and the complex
  matrix y as output.

  For equations and other information, see Volume 3: UNICOS Math and
  Scientific Library Reference Manual SR-2081 7.0, Cray Research, Inc.

NOTE

  Calling CFFT3D with isign set to '80FF0FF0FF0FF0FF'X initiates an escape.
  Please see the sciport man page for details. The escape mechanism should be
  inserted immediately after the last call to CFFT3D for which the status of
  table is known. This mechanism should be used sparingly. Its use implies
  frequent re-initializations of the sine and cosine tables - which are quite
  costly.

  See also sciport.