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annotate scripts/specfun/perms.m @ 10821:693e22af08ae
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| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Mon, 26 Jul 2010 21:25:36 -0700 |
| parents | 804c21f3659b |
| children | fd0a3ac60b0e |
| rev | line source |
|---|---|
| 9245 | 1 ## Copyright (C) 2001, 2006, 2007, 2009 Paul Kienzle |
| 9836 | 2 ## Copyright (C) 2009 VZLU Prague |
| 5827 | 3 ## |
| 4 ## This file is part of Octave. | |
| 5 ## | |
| 6 ## Octave is free software; you can redistribute it and/or modify it | |
| 7 ## under the terms of the GNU General Public License as published by | |
| 7016 | 8 ## the Free Software Foundation; either version 3 of the License, or (at |
| 9 ## your option) any later version. | |
| 5827 | 10 ## |
| 11 ## Octave is distributed in the hope that it will be useful, but | |
| 12 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 14 ## General Public License for more details. | |
| 15 ## | |
| 16 ## You should have received a copy of the GNU General Public License | |
| 7016 | 17 ## along with Octave; see the file COPYING. If not, see |
| 18 ## <http://www.gnu.org/licenses/>. | |
| 5827 | 19 |
| 20 ## -*- texinfo -*- | |
| 21 ## @deftypefn {Function File} {} perms (@var{v}) | |
| 22 ## | |
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23 ## Generate all permutations of @var{v}, one row per permutation. The |
| 5827 | 24 ## result has size @code{factorial (@var{n}) * @var{n}}, where @var{n} |
| 25 ## is the length of @var{v}. | |
| 26 ## | |
| 6754 | 27 ## As an example, @code{perms([1, 2, 3])} returns the matrix |
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10821
693e22af08ae
Grammarcheck documentation of m-files
Rik <octave@nomad.inbox5.com>
parents:
9836
diff
changeset
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28 ## |
| 6754 | 29 ## @example |
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parents:
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30 ## @group |
| 6754 | 31 ## 1 2 3 |
| 32 ## 2 1 3 | |
| 33 ## 1 3 2 | |
| 34 ## 2 3 1 | |
| 35 ## 3 1 2 | |
| 36 ## 3 2 1 | |
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9051
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Grammar check TexInfo in all .m files
Rik <rdrider0-list@yahoo.com>
parents:
7017
diff
changeset
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37 ## @end group |
| 6754 | 38 ## @end example |
| 5827 | 39 ## @end deftypefn |
| 40 | |
| 41 function A = perms (v) | |
| 6391 | 42 if (nargin != 1) |
| 43 print_usage (); | |
| 44 endif | |
| 5827 | 45 v = v(:); |
| 46 n = length (v); | |
| 9836 | 47 |
| 48 if (n == 0) | |
| 49 A = []; | |
| 5827 | 50 else |
| 9836 | 51 A = v(1); |
| 52 for j = 2:n | |
| 53 B = A; | |
| 54 A = zeros (prod (2:j), n, class (v)); | |
| 55 k = size (B, 1); | |
| 56 idx = 1:k; | |
| 57 for i = j:-1:1 | |
| 58 A(idx,1:i-1) = B(:,1:i-1); | |
| 59 A(idx,i) = v(j); | |
| 60 A(idx,i+1:j) = B(:,i:j-1); | |
| 61 idx += k; | |
| 62 endfor | |
| 5827 | 63 endfor |
| 64 endif | |
| 65 endfunction |