Contents

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

NAME

     dffti - 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)
               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.