dffti(3P) Sun Performance Library dffti(3P)NAMEdffti - initialize the array WSAVE, which is used in both DFFTF and
DFFTB.
SYNOPSIS
SUBROUTINE DFFTI(N, WSAVE)
INTEGER N
DOUBLE PRECISION WSAVE(*)
SUBROUTINE DFFTI_64(N, WSAVE)
INTEGER*8 N
DOUBLE PRECISION WSAVE(*)
F95 INTERFACE
SUBROUTINE FFTI(N, WSAVE)
INTEGER :: N
REAL(8), DIMENSION(:) :: WSAVE
SUBROUTINE FFTI_64(N, WSAVE)
INTEGER(8) :: N
REAL(8), DIMENSION(:) :: WSAVE
C INTERFACE
#include <sunperf.h>
void dffti(int n, double *wsave);
void dffti_64(long n, double *wsave);
ARGUMENTS
N (input) Length of the sequence to be transformed. N >= 0.
WSAVE (input/output)
On entry, an array of dimension (2 * N + 15) or greater.
DFFTI needs to be called only once to initialize array WORK
before calling DFFTF and/or DFFTB if N and WSAVE remain
unchanged between these calls. Thus, subsequent transforms
or inverse transforms of same size can be obtained faster
than the first since they do not require initialization of
the workspace.
6 Mar 2009 dffti(3P)