Contents
cost - 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).
SUBROUTINE COST(N, X, WSAVE)
INTEGER N
REAL X(*), WSAVE(*)
SUBROUTINE COST_64(N, X, WSAVE)
INTEGER*8 N
REAL X(*), WSAVE(*)
F95 INTERFACE
SUBROUTINE COST(N, X, WSAVE)
INTEGER :: N
REAL, DIMENSION(:) :: X, WSAVE
SUBROUTINE COST_64(N, X, WSAVE)
INTEGER(8) :: N
REAL, DIMENSION(:) :: X, WSAVE
C INTERFACE
#include <sunperf.h>
void cost(int n, float *x, float *wsave);
void cost_64(long n, float *x, float *wsave);
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 COSTI.