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comparison main/general/ifftshift.m @ 0:6b33357c7561 octave-forge

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Initial revision
author pkienzle
date Wed, 10 Oct 2001 19:54:49 +0000
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children 9a986e3452a4
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-1:000000000000 0:6b33357c7561
1 ## Copyright (C) 1997 by Vincent Cautaerts
2 ##
3 ## This program is free software; you can redistribute it and/or modify
4 ## it under the terms of the GNU General Public License as published by
5 ## the Free Software Foundation; either version 2, or (at your option)
6 ## any later version.
7 ##
8 ## This program is distributed in the hope that it will be useful, but
9 ## WITHOUT ANY WARRANTY; without even the implied warranty of
10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 ## General Public License for more details.
12 ##
13 ## You should have received a copy of the GNU General Public License
14 ## along with this file. If not, write to the Free Software Foundation,
15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
16
17 ## -*- texinfo -*-
18 ## @deftypefn {Function File} {} ifftshift (@var{v})
19 ## Undo the action of the fftshift function. For even length @var{v}, fftshift
20 ## is its own inverse, but odd lengths differ slightly.
21 ## @end deftypefn
22
23 ## Author: Vincent Cautaerts <vincent@comf5.comm.eng.osaka-u.ac.jp>
24 ## Created: July 1997
25 ## Adapted-By: jwe
26 ## Modified-By: Paul Kienzle, converted from fftshift
27
28 function retval = ifftshift (V)
29
30 retval = 0;
31
32 if (nargin != 1)
33 usage ("usage: ifftshift (X)");
34 endif
35
36 if (is_vector (V))
37 x = length (V);
38 xx = floor (x/2);
39 retval = V([xx+1:x, 1:xx]);
40 elseif (is_matrix (V))
41 [x, y] = size (V);
42 xx = floor (x/2);
43 yy = floor (y/2);
44 retval = V([xx+1:x, 1:xx], [yy+1:y, 1:yy]);
45 else
46 error ("ifftshift: expecting vector or matrix argument");
47 endif
48
49 endfunction