sfft_init_2d, dfft_init_2d, cfft_init_2d, zfft_init_2d 

Initialization step for fast fourier transform in two dimensions

FORMAT

  status = {S,D,C,Z}FFT_INIT_2D (ni, nj, fft_struct, ni_stride_1_flag)

Arguments

  ni, nj              integer*4
                      Specifies the size of the first and second dimension of
                      data in the input array; ni > 0, nj > 0.  For
                      SFFT_INIT_2D and DFFT_INIT_2D, ni must be even.

  fft_struct          record /dxml_s_fft_structure_2d/ for single-precision
                      real operations
                      record /dxml_d_fft_structure_2d/ for double-precision
                      real operations
                      record /dxml_c_fft_structure_2d/ for single-precision
                      complex operations
                      record /dxml_z_fft_structure_2d/ for double-precision
                      complex operations
                      This argument must be included but needs no additional
                      definitions. The argument is declared in the program
                      before this routine.  See the CXML Reference Guide 
                      for more information.

  ni_stride_1_flag    logical
                      Specifies whether to allow a stride of more than 1
                      between elements in the row:

                      TRUE: Stride must be 1.

                      FALSE: Stride is at least 1.

Description

  The _FFT_INIT_2D functions build internal data structures needed to compute
  fast Fourier transforms of two-dimensional data. These routines are the
  first step in a three-step procedure.  They create the internal data
  structures, using attributes defined in the file CXMLDEF.FOR.

  Use the initialization routine that is appropriate for the data format.
  Then, use the corresponding application and exit steps to complete the
  procedure. For example, use the SFFT_2D_INIT routine with the SFFT_2D_APPLY
  and SFFT_2D_EXIT routine.

Return Values

  0                  DXML_SUCCESS()

  4 (real transform only)
                     DXML_ILL_N_IS_ODD()

  8                  DXML_ILL_N_RANGE()

  12                 DXML_INS_RES()