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1 ## Copyright (C) 1995, 1996, 1997 Friedrich Leisch |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {} spencer (@var{x}) |
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21 ## Return Spencer's 15 point moving average of every single column of |
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22 ## @var{x}. |
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23 ## @end deftypefn |
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24 |
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25 ## Author: FL <Friedrich.Leisch@ci.tuwien.ac.at> |
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26 ## Description: Apply Spencer's 15-point MA filter |
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27 |
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28 function retval = spencer (X) |
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29 |
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30 if (nargin != 1) |
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31 print_usage (); |
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32 endif |
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33 |
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34 [xr, xc] = size(X); |
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35 |
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36 n = xr; |
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37 c = xc; |
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38 |
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39 if (isvector(X)) |
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40 n = length(X); |
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41 c = 1; |
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42 X = reshape(X, n, 1); |
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43 endif |
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44 |
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45 W = [-3, -6, -5, 3, 21, 46, 67, 74, 67, 46, 21, 3, -5, -6, -3] / 320; |
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46 |
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47 retval = fftfilt (W, X); |
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48 retval = [zeros(7,c); retval(15:n,:); zeros(7,c);]; |
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49 |
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50 retval = reshape(retval, xr, xc); |
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51 |
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52 endfunction |
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