zfft2i

NAME

zfft2i - initialize the array WSAVE, which is used in both the forward and backward transforms.

SYNOPSIS

  SUBROUTINE ZFFT2I( M, N, WORK)
  INTEGER M, N
  DOUBLE PRECISION WORK(*)
 
  SUBROUTINE ZFFT2I_64( M, N, WORK)
  INTEGER*8 M, N
  DOUBLE PRECISION WORK(*)

F95 INTERFACE

  SUBROUTINE ZFFT2I( M, N, WORK)
  INTEGER :: M, N
  REAL(8), DIMENSION(:) :: WORK
 
  SUBROUTINE ZFFT2I_64( M, N, WORK)
  INTEGER(8) :: M, N
  REAL(8), DIMENSION(:) :: WORK

C INTERFACE

#include <sunperf.h>

void zfft2i(int m, int n, double *work);

void zfft2i_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 (4 * (M + N) + 30) or greater. ZFFT2I needs to be called only once to initialize array WORK before calling ZFFT2F and/or ZFFT2B 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.