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1 ## Copyright (C) 1996, 1997 John W. Eaton |
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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 2, or (at your option) |
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8 ## 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, write to the Free |
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17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} issymmetric (@var{x}, @var{tol}) |
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22 ## If @var{x} is symmetric within the tolerance specified by @var{tol}, |
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23 ## then return the dimension of @var{x}. Otherwise, return 0. If |
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24 ## @var{tol} is omitted, use a tolerance equal to the machine precision. |
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25 ## @end deftypefn |
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26 ## |
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27 ## @seealso{size, rows, columns, length, ismatrix, isscalar, |
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28 ## issquare, and isvector} |
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29 |
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30 ## Author: A. S. Hodel <scotte@eng.auburn.edu> |
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31 ## Created: August 1993 |
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32 ## Adapted-By: jwe |
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33 |
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34 function retval = issymmetric (x,tol) |
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35 |
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36 if (nargin == 1 || nargin == 2) |
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37 retval = issquare (x); |
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38 if (retval != 0) |
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39 if (nargin == 1) |
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40 tol = eps; |
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41 endif |
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42 norm_x = norm (x); |
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43 if (norm_x != 0 && norm (x - x') / norm_x > tol) |
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44 retval = 0; |
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45 endif |
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46 endif |
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47 else |
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48 usage ("issymmetric (x {,tol})"); |
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49 endif |
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50 |
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51 endfunction |
