Name

sfct, dfct − Fast cosine transform in one dimension

FORMAT

status = {S,D}FCT (direction, in, out, n, type, stride)

Arguments

directioncharacter∗(∗)
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.  For type-I FCT, the length of the IN,OUT array must must be

ninteger∗4
Specifies the size of the transform. The minimum size of the IN, OUT array is n; where n
 and even.

typeinteger∗4
Specifies the type of the Cosine transform desired. Currently only type-1 and type-2 transforms are supported.

strideinteger∗4
Specifies the distance between consecutive elements in the IN and OUT arrays. The distance must be at least 1.

Description

The _FCT functions compute the fast Cosine transform of one-dimensional data in one step. 

Return Values

0DXML_SUCCESS()

4DXML_ILL_N_IS_ODD()

8DXML_ILL_N_RANGE()

12DXML_INS_RES()

13DXML_BAD_STRIDE()

15DXML_BAD_DIRECTION_STRING()

17DXML_OPTION_NOT_SUPPORTED()

Example

INTEGER∗4 N
PARAMETER (N=1024)
INCLUDE ’{file_location}DXMLDEF.FOR’
INTEGER∗4 STATUS
REAL∗8 C(0:N),D(0:N)
REAL∗4 E(1:N-1),F(1:N-1)
STATUS = DFCT(’F’,C,D,N,1,1)
STATUS = DFCT(’B’,D,C,N,1,1)
STATUS = SFCT(’F’,E,F,N,2,1)
STATUS = SFCT(’B’,F,E,N,2,1)

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.