sfct_apply, dfct_apply 

Application step for fast cosine transform in one dimension

FORMAT

  status = {S,D}FCT_APPLY (direction, in, out, fct_struct, stride)

Arguments

  direction           character*(*)
                      Specifies the operation as either the forward or
                      inverse transform. Use Use 'B' or

  in, out             real*4 | real*8
                      Both the arguments are one-dimensional arrays.  The
                      input and output arrays can be the same array. The IN
                      array contains the data to be transformed. The OUT
                      array contains the transformed data.

  fct_struct          record /dxml_s_fct_structure/ for single-precision
                      operations
                      record /dxml_d_fct_structure/ for double-precision
                      operations

  stride              integer*4
                      Specifies the distance between consecutive elements in
                      the input and output arrays, depending on the value of
                      stride_1_flag provided in the _INIT function.

Description

  The _FCT_APPLY functions compute the fast Cosine transform of one-
  dimensional data in three steps.

Return Values

  0                  DXML_SUCCESS()

  12                 DXML_INS_RES()

  13                 DXML_BAD_STRIDE()

  15                 DXML_BAD_DIRECTION_STRING()

  17                 DXML_OPTION_NOT_SUPPORTED()

Example

  INTEGER*4 N
  PARAMETER (N=1024)
  INCLUDE 'CXMLDEF.FOR'
  INTEGER*4 STATUS
  RECORD /CXML_S_FCT_STRUCTURE/ D_FCT_STRUCT
  RECORD /CXML_D_FCT_STRUCTURE/ D_FCT_STRUCT
  REAL*8 C(0:N),D(0:N)
  REAL*4 E(0:N-1),F(0:N-1)
  STATUS = DFCT_INIT(N,D_FCT_STRUCT,1,.TRUE.)
  STATUS = DFCT_APPLY('F',C,D,D_FCT_STRUCT,1)
  STATUS = DFCT_APPLY('B',D,C,D_FCT_STRUCT,1)
  STATUS = DFCT_EXIT(D_FCT_STRUCT)
  STATUS = SFCT_INIT(N,S_FCT_STRUCT,2,.TRUE.)
  STATUS = SFCT_APPLY('F',E,F,S_FCT_STRUCT,1)
  STATUS = SFCT_APPLY('B',F,E,S_FCT_STRUCT,1)
  STATUS = SFCT_EXIT(D_FCT_STRUCT)

  This FORTRAN code computes the following:

  •  Forward Type-1 Cosine transform of the real sequence C to real sequence
     D.

  •  Backward Type-1 Cosine transform of the real sequence D to real sequence
     C.

  •  Forward Type-2 Cosine transform of the real sequence E to real sequence
     F.

  •  Backward Type-2 Cosine transform of the real sequence F to real sequence
     E.