1 ## Copyright (C) 1995-2012 Friedrich Leisch
3 ## This file is part of Octave.
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.
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.
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/>.
20 ## @deftypefn {Function File} {} spencer (@var{x})
21 ## Return Spencer's 15 point moving average of each column of
25 ## Author: FL <Friedrich.Leisch@ci.tuwien.ac.at>
26 ## Description: Apply Spencer's 15-point MA filter
28 function retval = spencer (x)
45 w = [-3, -6, -5, 3, 21, 46, 67, 74, 67, 46, 21, 3, -5, -6, -3] / 320;
47 retval = fftfilt (w, x);
48 retval = [zeros(7,c); retval(15:n,:); zeros(7,c);];
50 retval = reshape(retval, xr, xc);