Contents

• NAME
• SYNOPSIS
  • F95 INTERFACE
  • C INTERFACE
• ARGUMENTS

NAME

     vdffti - initialize the array WSAVE, which is used  in  both
     VRFFTF and VRFFTB.

SYNOPSIS

     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);

ARGUMENTS

     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.