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1 ## Copyright (C) 2004, 2005, 2006, 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{s} =} spalloc (@var{r}, @var{c}, @var{nz}) |
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21 ## Returns an empty sparse matrix of size @var{r}-by-@var{c}. As Octave |
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22 ## resizes sparse matrices at the first opportunity, so that no additional |
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23 ## space is needed, the argument @var{nz} is ignored. This function is |
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24 ## provided only for compatibility reasons. |
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25 ## |
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26 ## It should be noted that this means that code like |
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27 ## |
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28 ## @example |
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29 ## k = 5; |
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30 ## nz = r * k; |
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31 ## s = spalloc (r, c, nz) |
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32 ## for j = 1:c |
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33 ## idx = randperm (r); |
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34 ## s (:, j) = [zeros(r - k, 1); rand(k, 1)] (idx); |
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35 ## endfor |
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36 ## @end example |
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37 ## |
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38 ## will reallocate memory at each step. It is therefore vitally important |
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39 ## that code like this is vectorized as much as possible. |
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40 ## @seealso{sparse, nzmax} |
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41 ## @end deftypefn |
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42 |
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43 function s = spalloc (r, c, nz) |
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44 |
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45 if (nargin < 2) |
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46 print_usage (); |
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47 endif |
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48 |
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49 s = sparse (r, c); |
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50 endfunction |
