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zffti - initialize the array WSAVE, which is used in both
ZFFTF and ZFFTB.

SUBROUTINE ZFFTI(N, WSAVE)
INTEGER N
DOUBLE PRECISION WSAVE(*)
SUBROUTINE ZFFTI_64(N, WSAVE)
INTEGER*8 N
DOUBLE PRECISION WSAVE(*)
**F95 INTERFACE**
SUBROUTINE ZFFTI(N, WSAVE)
INTEGER :: N
REAL(8), DIMENSION(:) :: WSAVE
SUBROUTINE ZFFTI_64(N, WSAVE)
INTEGER(8) :: N
REAL(8), DIMENSION(:) :: WSAVE
**C INTERFACE**
#include <sunperf.h>
void zffti(int n, double *wsave);
void zffti_64(long n, double *wsave);

N (input) Length of the sequence to be transformed. N >= 0.
WSAVE (input/output)
On entry, an array of dimension (4 * N + 15) or
greater. ZFFTI needs to be called only once to
initialize array WORK before calling ZFFTF and/or
ZFFTB 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.