vzffti

NAME

vzffti - initialize the array WSAVE, which is used in both VZFFTF and VZFFTB.

SYNOPSIS

  SUBROUTINE VZFFTI( N, WSAVE)
  DOUBLE COMPLEX WSAVE(*)
  INTEGER N
 
  SUBROUTINE VZFFTI_64( N, WSAVE)
  DOUBLE COMPLEX WSAVE(*)
  INTEGER*8 N

F95 INTERFACE

  SUBROUTINE VFFTI( N, WSAVE)
  COMPLEX(8), DIMENSION(:) :: WSAVE
  INTEGER :: N
 
  SUBROUTINE VFFTI_64( N, WSAVE)
  COMPLEX(8), DIMENSION(:) :: WSAVE
  INTEGER(8) :: N

C INTERFACE

#include <sunperf.h>

void vzffti(int n, doublecomplex *wsave);

void vzffti_64(long n, doublecomplex *wsave);

ARGUMENTS

* N (input): Length of the sequence to be transformed. N >= 0.
* WSAVE (input): On entry, an array of dimension (N + 15) or greater. VZFFTI needs to be called only once to initialize WSAVE before calling VZFFTF and/or VZFFTB 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.