sfft_init_grp, dfft_init_grp, cfft_init_grp, zfft_init_grp 

Initialization step for group fast fourier transform in one dimension

FORMAT

  status = {S,D,C,Z}FFT_INIT_GRP (n, fft_struct, grp_stride_1_flag,
  max_grp_size)

Arguments

  n                   integer*4
                      Specifies the number of elements in the column within
                      each one-dimensional data array; n > 0.  For
                      SFFT_INIT_GRP and DFFT_INIT_GRP, n must be even.

  fft_struct          record /dxml_s_grp_fft_structure/ for single-precision
                      real operations
                      record /dxml_d_grp_fft_structure/ for double-precision
                      real operations
                      record /dxml_c_grp_fft_structure/ for single-precision
                      complex operations
                      record /dxml_z_grp_fft_structure/ for double-precision
                      complex operations
                      You must include this argument but it needs no
                      additional definitions. The argument is declared in the
                      program before this routine.  See
                      the CXML Reference Guide  for more information.

  grp_stride_1_flag   logical
                      Specifies whether to allow a distance greater than 1
                      between elements.

                      TRUE: Group stride must be 1.

                      FALSE: Group stride is at least 1.

  max_grp_size        integer*4
                      Specifies the expected number of sets of data. If
                      unknown, set max_grp_size = 0.

Description

  The _FFT_INIT_GRP functions build internal data structures needed to
  compute fast Fourier transforms of one-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.

Return Values

  0                  DXML_SUCCESS()

  4 (real transforms only)
                     DXML_ILL_N_IS_ODD()

  8                  DXML_ILL_N_RANGE()

  12                 DXML_INS_RES()