Mercurial > hg > octave-nkf
diff scripts/signal/ifftshift.m @ 5820:27c966e4b2dc
[project @ 2006-05-17 21:00:54 by jwe]
author | jwe |
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date | Wed, 17 May 2006 21:00:54 +0000 |
parents | |
children | 34f96dd5441b |
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new file mode 100644 --- /dev/null +++ b/scripts/signal/ifftshift.m @@ -0,0 +1,72 @@ +## Copyright (C) 1997 by Vincent Cautaerts +## +## Octave is free software; you can redistribute it and/or modify it +## under the terms of the GNU General Public License as published by +## the Free Software Foundation; either version 2, or (at your option) +## any later version. +## +## Octave is distributed in the hope that it will be useful, but +## WITHOUT ANY WARRANTY; without even the implied warranty of +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +## General Public License for more details. +## +## You should have received a copy of the GNU General Public License +## along with Octave; see the file COPYING. If not, write to the Free +## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +## 02110-1301, USA. + +## -*- texinfo -*- +## @deftypefn {Function File} {} ifftshift (@var{v}) +## @deftypefnx {Function File} {} ifftshift (@var{v}, @var{dim}) +## Undo the action of the @code{fftshift} function. For even length +## @var{v}, @code{fftshift} is its own inverse, but odd lengths differ +## slightly. +## @end deftypefn + +## Author: Vincent Cautaerts <vincent@comf5.comm.eng.osaka-u.ac.jp> +## Created: July 1997 +## Adapted-By: jwe +## Modified-By: Paul Kienzle, converted from fftshift +## Modified-By: David Bateman, add NDArray capability and option dim arg + +function retval = ifftshift (V, dim) + + retval = 0; + + if (nargin != 1 && nargin != 2) + usage ("usage: ifftshift (X, dim)"); + endif + + if (nargin == 2) + if (!isscalar (dim)) + error ("ifftshift: dimension must be an integer scalar"); + endif + nd = ndims (V); + sz = size (V); + sz2 = floor (sz(dim) / 2); + idx = cell (); + for i=1:nd + idx {i} = 1:sz(i); + endfor + idx {dim} = [sz2+1:sz(dim), 1:sz2]; + retval = V (idx{:}); + else + if (isvector (V)) + x = length (V); + xx = floor (x/2); + retval = V([xx+1:x, 1:xx]); + elseif (ismatrix (V)) + nd = ndims (V); + sz = size (V); + sz2 = floor (sz ./ 2); + idx = cell (); + for i=1:nd + idx{i} = [sz2(i)+1:sz(i), 1:sz2(i)]; + endfor + retval = V (idx{:}); + else + error ("ifftshift: expecting vector or matrix argument"); + endif + endif + +endfunction