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1 ## Copyright (C) 1995, 1996, 1997 Kurt Hornik |
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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 2, or (at your option) |
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8 ## 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, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} studentize (@var{x}, @var{dim}) |
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22 ## If @var{x} is a vector, subtract its mean and divide by its standard |
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23 ## deviation. |
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24 ## |
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25 ## If @var{x} is a matrix, do the above along the first non-singleton |
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26 ## dimension. If the optional argument @var{dim} is given then operate |
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27 ## along this dimension. |
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28 ## @end deftypefn |
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29 |
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30 ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> |
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31 ## Description: Subtract mean and divide by standard deviation |
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32 |
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33 function t = studentize (x, dim) |
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34 |
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35 if (nargin != 1 && nargin != 2) |
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36 usage ("studentize (x, dim)"); |
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37 endif |
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38 |
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39 nd = ndims (x); |
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40 sz = size (x); |
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41 if (nargin != 2) |
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42 ## Find the first non-singleton dimension. |
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43 dim = 1; |
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44 while (dim < nd + 1 && sz(dim) == 1) |
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45 dim = dim + 1; |
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46 endwhile |
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47 if (dim > nd) |
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48 dim = 1; |
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49 endif |
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50 else |
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51 if (! (isscalar (dim) && dim == round (dim)) |
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52 && dim > 0 |
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53 && dim < (nd + 1)) |
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54 error ("studentize: dim must be an integer and valid dimension"); |
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55 endif |
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56 endif |
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57 |
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58 if (! ismatrix (x)) |
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59 error ("studentize: x must be a vector or a matrix"); |
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60 endif |
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61 |
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62 c = sz(dim); |
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63 idx = ones (1, nd); |
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64 idx(dim) = c; |
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65 t = x - repmat (mean (x, dim), idx); |
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66 t = t ./ repmat (max (cat (dim, std(t, [], dim), ! any (t, dim)), [], dim), idx); |
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67 |
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68 endfunction |
