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1 ## Copyright (C) 1995, 1996, 1997 Friedrich Leisch |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify |
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4 ## it under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 2, or (at your option) |
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6 ## any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, but |
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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11 ## General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this file. If not, write to the Free Software Foundation, |
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15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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16 |
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17 ## usage: spencer (X) |
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18 ## |
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19 ## returns Spencer's 15 point moving average of every single column of X |
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20 |
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21 ## Author: FL <Friedrich.Leisch@ci.tuwien.ac.at> |
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22 ## Description: Apply Spencer's 15-point MA filter |
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23 |
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24 function retval = spencer (X) |
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25 |
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26 if (nargin != 1) |
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27 usage ("spencer (X)"); |
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28 endif |
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29 |
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30 [xr, xc] = size(X); |
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31 |
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32 n = xr; |
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33 c = xc; |
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34 |
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35 if (is_vector(X)) |
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36 n = length(X); |
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37 c = 1; |
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38 X = reshape(X, n, 1); |
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39 endif |
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40 |
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41 W = [-3, -6, -5, 3, 21, 46, 67, 74, 67, 46, 21, 3, -5, -6, -3] / 320; |
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42 |
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43 retval = fftfilt (W, X); |
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44 retval = [zeros(7,c); retval(15:n,:); zeros(7,c);]; |
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45 |
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46 retval = reshape(retval, xr, xc); |
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47 |
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48 endfunction |
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