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1 ## Copyright (C) 2001 Paul Kienzle |
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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 of the License, or |
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6 ## (at your option) 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, |
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9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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11 ## GNU 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 program; if not, write to the Free Software |
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15 ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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16 |
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17 ## A = perms(v) |
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18 ## generate all permutations of v, one row per permutation. |
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19 ## The resulting A has size n! x n, where n is the length of v |
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20 ## so keep v small! |
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21 function A = perms(v) |
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22 n = length(v); |
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23 if (n == 1) |
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24 A = v; |
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25 else |
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26 B = perms(v(1:n-1)); |
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27 Bidx = 1:size(B,1); |
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28 A = v(n) * ones(prod(2:n), n); |
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29 A (Bidx, 1:n-1) = B; |
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30 k = size(B,1); |
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31 for i = n-1:-1:2 |
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32 A (k+Bidx, 1:i-1) = B(Bidx, 1:i-1); |
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33 A (k+Bidx, i+1:n) = B(Bidx, i:n-1); |
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34 k = k + size(B,1); |
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35 end |
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36 A (k+Bidx, 2:n) = B; |
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37 endif |
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38 endfunction |
