Contents
vdffti - initialize the array WSAVE, which is used in both
VRFFTF and VRFFTB.
SUBROUTINE VDFFTI(N, WSAVE)
INTEGER N
DOUBLE PRECISION WSAVE(*)
SUBROUTINE VDFFTI_64(N, WSAVE)
INTEGER*8 N
DOUBLE PRECISION WSAVE(*)
F95 INTERFACE
SUBROUTINE VFFTI(N, WSAVE)
INTEGER :: N
REAL(8), DIMENSION(:) :: WSAVE
SUBROUTINE VFFTI_64(N, WSAVE)
INTEGER(8) :: N
REAL(8), DIMENSION(:) :: WSAVE
C INTERFACE
#include <sunperf.h>
void vdffti(int n, double *wsave);
void vdffti_64(long n, double *wsave);
N (input) Length of the sequence to be transformed. N >= 0.
WSAVE (input)
On entry, an array of dimension (N + 15) or
greater. VRFFTI needs to be called only once to
initialize WSAVE before calling VRFFTF and/or
VRFFTB 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.