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scripts/signal/ifftshift.m

changeset 10289: 4b124317dc38
parent:cadc73247d65
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (29 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1997, 2006, 2007, 2009 by Vincent Cautaerts

     2##

     3## This file is part of Octave.

     4##

     5## Octave is free software; you can redistribute it and/or modify it

     6## under the terms of the GNU General Public License as published by

     7## the Free Software Foundation; either version 3 of the License, or (at

     8## your option) any later version.

     9##

    10## Octave is distributed in the hope that it will be useful, but

    11## WITHOUT ANY WARRANTY; without even the implied warranty of

    12## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    13## General Public License for more details.

    14##

    15## You should have received a copy of the GNU General Public License

    16## along with Octave; see the file COPYING.  If not, see

    17## <http://www.gnu.org/licenses/>.

    18

    19## -*- texinfo -*-

    20## @deftypefn {Function File} {} ifftshift (@var{v})

    21## @deftypefnx {Function File} {} ifftshift (@var{v}, @var{dim})

    22## Undo the action of the @code{fftshift} function.  For even length 

    23## @var{v}, @code{fftshift} is its own inverse, but odd lengths differ 

    24## slightly.

    25## @end deftypefn

    26

    27## Author: Vincent Cautaerts <vincent@comf5.comm.eng.osaka-u.ac.jp>

    28## Created: July 1997

    29## Adapted-By: jwe

    30## Modified-By: Paul Kienzle, converted from fftshift

    31## Modified-By: David Bateman, add NDArray capability and option dim arg

    32

    33function retval = ifftshift (V, dim)

    34

    35  retval = 0;

    36

    37  if (nargin != 1 && nargin != 2)

    38    print_usage ();

    39  endif

    40

    41  if (nargin == 2)

    42    if (! isscalar (dim))

    43      error ("ifftshift: dimension must be an integer scalar");

    44    endif

    45    nd = ndims (V);

    46    sz = size (V);

    47    sz2 = floor (sz(dim) / 2);

    48    idx = cell ();

    49    for i = 1:nd

    50      idx{i} = 1:sz(i);

    51    endfor

    52    idx{dim} = [sz2+1:sz(dim), 1:sz2];

    53    retval = V (idx{:});

    54  else

    55    if (isvector (V))

    56      x = length (V);

    57      xx = floor (x/2);

    58      retval = V([xx+1:x, 1:xx]);

    59    elseif (ismatrix (V))

    60      nd = ndims (V);

    61      sz = size (V);

    62      sz2 = floor (sz ./ 2);

    63      idx = cell ();

    64      for i = 1:nd

    65        idx{i} = [sz2(i)+1:sz(i), 1:sz2(i)];

    66      endfor

    67      retval = V (idx{:});

    68    else

    69      error ("ifftshift: expecting vector or matrix argument");

    70    endif

    71  endif

    72

    73endfunction