Contents

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

NAME

     dfft2i - initialize the array WSAVE, which is used  in  both
     the forward and backward transforms.

SYNOPSIS

     SUBROUTINE DFFT2I(M, N, WORK)

     INTEGER M, N
     DOUBLE PRECISION WORK(*)

     SUBROUTINE DFFT2I_64(M, N, WORK)

     INTEGER*8 M, N
     DOUBLE PRECISION WORK(*)

  F95 INTERFACE
     SUBROUTINE FFT2I(M, N, WORK)

     INTEGER :: M, N
     REAL(8), DIMENSION(:) :: WORK

     SUBROUTINE FFT2I_64(M, N, WORK)

     INTEGER(8) :: M, N
     REAL(8), DIMENSION(:) :: WORK

  C INTERFACE
     #include <sunperf.h>

     void dfft2i(int m, int n, double *work);

     void dfft2i_64(long m, long n, double *work);

ARGUMENTS

     M (input) Number of rows to be transformed.  M >= 0.

     N (input) Number of columns to be transformed.  N >= 0.

     WORK (input/output)
               On entry, an array of dimension (M + 2*N +  MAX(M,
               2*N)  + 30) or greater.  DFFT2I needs to be called
               only once to initialize array WORK before  calling
               DFFT2F  and/or  DFFT2B  if  M,  N  and WORK 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.