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1 ## Copyright (C) 1996, 1997 John W. Eaton |
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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, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} intersection (@var{x}, @var{y}) |
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22 ## Return the set of elements that are in both sets @var{x} and @var{y}. |
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23 ## For example, |
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24 ## |
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25 ## @example |
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26 ## @group |
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27 ## intersection ([ 1, 2, 3 ], [ 2, 3, 5 ]) |
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28 ## @result{} [ 2, 3 ] |
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29 ## @end group |
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30 ## @end example |
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31 ## @end deftypefn |
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32 ## |
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33 ## @seealso{create_set, union, and complement} |
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34 |
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35 ## Author: jwe |
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36 |
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37 function y = intersection(a,b) |
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38 |
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39 if (nargin != 2) |
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40 usage ("intersection(a,b)"); |
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41 endif |
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42 |
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43 if(isempty(a) || isempty(b)) |
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44 y = []; |
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45 return; |
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46 endif |
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47 |
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48 a = create_set(a); |
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49 b = create_set(b); |
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50 |
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51 if(length(a) < length(b)) |
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52 yindex = 1; |
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53 y = zeros(1,length(a)); |
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54 for index = 1:length(a) |
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55 if(any(b == a(index))) |
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56 y(yindex++) = a(index); |
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57 endif |
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58 endfor |
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59 else |
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60 yindex = 1; |
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61 y = zeros(1,length(b)); |
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62 for index = 1:length(b) |
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63 if(any(a == b(index))) |
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64 y(yindex++) = b(index); |
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65 endif |
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66 endfor |
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67 endif |
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68 |
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69 y = y(1:(yindex-1)); |
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70 |
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71 endfunction |
