dcost(3P) Sun Performance Library dcost(3P)NAMEdcost - compute the discrete Fourier cosine transform of an even
sequence. The COST transforms are unnormalized inverses of themselves,
so a call of COST followed by another call of COST will multiply the
input sequence by 2 * (N-1).
SYNOPSIS
SUBROUTINE DCOST(N, X, WSAVE)
INTEGER N
DOUBLE PRECISION X(*), WSAVE(*)
SUBROUTINE DCOST_64(N, X, WSAVE)
INTEGER*8 N
DOUBLE PRECISION X(*), WSAVE(*)
F95 INTERFACE
SUBROUTINE COST([N], X, WSAVE)
INTEGER :: N
REAL(8), DIMENSION(:) :: X, WSAVE
SUBROUTINE COST_64([N], X, WSAVE)
INTEGER(8) :: N
REAL(8), DIMENSION(:) :: X, WSAVE
C INTERFACE
#include <sunperf.h>
void dcost(int n, double *x, double *wsave);
void dcost_64(long n, double *x, double *wsave);
ARGUMENTS
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. On exit, the cosine transform of the input.
WSAVE (input)
On entry, an array with dimension of at least (3 * N + 15),
initialized by DCOSTI.
6 Mar 2009 dcost(3P)
