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1 ## Copyright (C) 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2005, 2006, |
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2 ## 2007 John W. Eaton |
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3 ## |
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4 ## This file is part of Octave. |
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5 ## |
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6 ## Octave is free software; you can redistribute it and/or modify it |
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7 ## under the terms of the GNU General Public License as published by |
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8 ## the Free Software Foundation; either version 3 of the License, or (at |
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9 ## your option) any later version. |
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10 ## |
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11 ## Octave is distributed in the hope that it will be useful, but |
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 ## General Public License for more details. |
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15 ## |
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16 ## You should have received a copy of the GNU General Public License |
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17 ## along with Octave; see the file COPYING. If not, see |
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18 ## <http://www.gnu.org/licenses/>. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} triu (@var{a}, @var{k}) |
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22 ## See tril. |
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23 ## @end deftypefn |
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24 |
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25 ## Author: jwe |
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26 |
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27 function retval = triu (x, k) |
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28 |
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29 if (nargin > 0) |
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30 [nr, nc] = size (x); |
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31 retval = resize (resize (x, 0), nr, nc); |
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32 endif |
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33 |
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34 if (nargin == 1) |
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35 k = 0; |
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36 elseif (nargin == 2) |
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37 if ((k > 0 && k > nc) || (k < 0 && k < -nr)) |
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38 error ("triu: requested diagonal out of range"); |
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39 endif |
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40 else |
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41 print_usage (); |
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42 endif |
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43 |
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44 for j = max (1, k+1) : nc |
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45 nr_limit = min (nr, j-k); |
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46 retval (1:nr_limit, j) = x (1:nr_limit, j); |
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47 endfor |
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48 |
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49 endfunction |
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50 |
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51 %!test |
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52 %! a = [1, 2, 3; 4, 5, 6; 7, 8, 9; 10, 11, 12]; |
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53 %! |
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54 %! u0 = [1, 2, 3; 0, 5, 6; 0, 0, 9; 0, 0, 0]; |
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55 %! u1 = [0, 2, 3; 0, 0, 6; 0, 0, 0; 0, 0, 0]; |
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56 %! u2 = [0, 0, 3; 0, 0, 0; 0, 0, 0; 0, 0, 0]; |
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57 %! u3 = [0, 0, 0; 0, 0, 0; 0, 0, 0; 0, 0, 0]; |
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58 %! um1 = [1, 2, 3; 4, 5, 6; 0, 8, 9; 0, 0, 12]; |
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59 %! um2 = [1, 2, 3; 4, 5, 6; 7, 8, 9; 0, 11, 12]; |
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60 %! um3 = [1, 2, 3; 4, 5, 6; 7, 8, 9; 10, 11, 12]; |
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61 %! |
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62 %! assert((triu (a, -3) == um3 && triu (a, -2) == um2 |
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63 %! && triu (a, -1) == um1 && triu (a) == u0 && triu (a, 1) == u1 |
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64 %! && triu (a, 2) == u2 && triu (a, 3) == u3)); |
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65 |
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66 %!error triu (); |
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67 |
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68 %!error triu (1, 2, 3); |
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69 |
