vcost

NAME

vcost - compute the discrete Fourier cosine transform of an even sequence. The VCOST transform is normalized, so a call of VCOST followed by a call of VCOST will return the original sequence.

SYNOPSIS

  SUBROUTINE VCOST( M, N, X, XT, MDIMX, WSAVE)
  INTEGER M, N, MDIMX
  REAL X(MDIMX,*), XT(MDIMX,*), WSAVE(*)
 
  SUBROUTINE VCOST_64( M, N, X, XT, MDIMX, WSAVE)
  INTEGER*8 M, N, MDIMX
  REAL X(MDIMX,*), XT(MDIMX,*), WSAVE(*)

F95 INTERFACE

  SUBROUTINE COST( [M], [N], X, XT, [MDIMX], WSAVE)
  INTEGER :: M, N, MDIMX
  REAL, DIMENSION(:) :: WSAVE
  REAL, DIMENSION(:,:) :: X, XT
 
  SUBROUTINE COST_64( [M], [N], X, XT, [MDIMX], WSAVE)
  INTEGER(8) :: M, N, MDIMX
  REAL, DIMENSION(:) :: WSAVE
  REAL, DIMENSION(:,:) :: X, XT

C INTERFACE

#include <sunperf.h>

void vcost(int m, int n, float *x, float *xt, int mdimx, float *wsave);

void vcost_64(long m, long n, float *x, float *xt, long mdimx, float *wsave);

ARGUMENTS

* M (input): The number of sequences to be transformed. M >= 0.
* N (input): Length of the sequence to be transformed. These subroutines are most efficient when N - 1 is a product of small primes. N >= 2.
* X (input/output): On entry, an array of length N containing the sequence to be transformed. For VCOST, a real two- dimensional array with dimensions of (MDIMX x (N+1)) whose rows contain the sequences to be transformed. On exit, the cosine transform of the input.
* XT (input): A real two-dimensional work array with dimensions of (MDIMX x (N-1)).
* MDIMX (input): Leading dimension of the arrays X and XT as specified in a dimension or type statement. MDIMX >= M.
* WSAVE (input): On entry, an array of dimension (2 * N + 15) or greater initialized by VCOSTI.