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annotate scripts/linear-algebra/cross.m @ 3238:041ea33fbbf4

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[project @ 1999-03-26 17:48:16 by jwe]
author jwe
date Fri, 26 Mar 1999 17:48:35 +0000
parents e6d14959bea9
children 6923abb04e16
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c3d634d49ce4 [project @ 1996-11-20 00:20:12 by jwe]
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1 ## Copyright (C) 1995, 1996 Kurt Hornik
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2 ##
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3 ## This program is free software; you can redistribute it and/or modify
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4 ## it under the terms of the GNU General Public License as published by
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5 ## the Free Software Foundation; either version 2, or (at your option)
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6 ## any later version.
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7 ##
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8 ## This program is distributed in the hope that it will be useful, but
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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11 ## General Public License for more details.
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12 ##
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13 ## You should have received a copy of the GNU General Public License
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14 ## along with this file. If not, write to the Free Software Foundation,
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15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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16
c3d634d49ce4 [project @ 1996-11-20 00:20:12 by jwe]
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17 ## usage: cross (x, y)
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18 ##
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19 ## Computes the vector cross product of the two 3-dimensional vectors
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20 ## x and y.
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21
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22 ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at>
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23 ## Created: 15 October 1994
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24 ## Adapted-By: jwe
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25
c3d634d49ce4 [project @ 1996-11-20 00:20:12 by jwe]
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26 function z = cross (x, y)
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27
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28 if (nargin != 2)
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29 usage ("cross (x, y)");
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30 endif
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31
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32 if (length (x) == 3 && length (y) == 3)
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33
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34 z = [x(2)*y(3) - x(3)*y(2); x(3)*y(1) - x(1)*y(3); x(1)*y(2) - x(2)*y(1)];
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35
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36 x_nr = rows (x);
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37 y_nr = rows (y);
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38
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39 if ((x_nr == y_nr && x_nr == 1)
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40 || (x_nr != y_nr && ! prefer_column_vectors))
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41 z = z.';
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42 endif
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43
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44 else
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45 error ("cross: both x and y must be 3-dimensional vectors");
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46 endif
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47
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48 endfunction