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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 |
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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 |
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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 (! (is_vector (x) && length (x) == 3 |
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33 && is_vector (y) && length (y) == 3)) |
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34 error ("cross: both x and y must be 3-dimensional vectors"); |
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35 endif |
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36 |
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37 x = reshape (x, 3, 1); |
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38 y = reshape (y, 3, 1); |
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39 e = eye (3, 3); |
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40 for k = 1 : 3 |
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41 z(k) = det ([x y e(:, k)]); |
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42 endfor |
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43 |
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44 endfunction |
