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annotate scripts/linear-algebra/trace.m @ 1887:5d29638dd524

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[project @ 1996-02-06 15:41:33 by jwe]
author jwe
date Tue, 06 Feb 1996 15:49:10 +0000
parents 611d403c7f3d
children 5cffc4b8de57
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1 # Copyright (C) 1996 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
16a24e76d6e0 [project @ 1993-12-03 02:00:15 by jwe]
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6 # under the terms of the GNU General Public License as published by the
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7 # Free Software Foundation; either version 2, or (at your option) any
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8 # later version.
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9 #
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10 # Octave is distributed in the hope that it will be useful, but WITHOUT
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11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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12 # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 # 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 02111-1307, USA.
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18
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19 function y = trace (x)
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20
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21 # usage: trace (x)
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22 #
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23 # Returns the trace (the sum of the diagonal elements) of x.
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25 if (nargin != 1)
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26 usage ("trace (x)");
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27 endif
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29 [nr, nc] = size (x);
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30 if (nr == 1 || nc == 1)
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31 y = x(1);
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32 else
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33 y = sum (diag (x));
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34 endif
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36 endfunction