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1 ## Copyright (C) 2004, 2005, 2007 David Bateman & Andy Adler |
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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} {@var{p} =} colperm (@var{s}) |
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21 ## Returns the column permutations such that the columns of |
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22 ## @code{@var{s} (:, @var{p})} are ordered in terms of increase number |
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23 ## of non-zero elements. If @var{s} is symmetric, then @var{p} is chosen |
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24 ## such that @code{@var{s} (@var{p}, @var{p})} orders the rows and |
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25 ## columns with increasing number of non zeros elements. |
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26 ## @end deftypefn |
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27 |
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28 function p = colperm (s) |
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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 [i, j] = spfind (s); |
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35 idx = find (diff ([j; Inf]) != 0); |
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36 [dummy, p] = sort (idx - [0; idx(1:(end-1))]); |
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37 endfunction |
