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1 ## Copyright (C) 1998 Auburn University. All rights reserved. |
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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 3 of the License, or (at |
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8 ## your option) 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, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {} qtransv (@var{v}, @var{q}) |
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21 ## Transform the 3-D vector @var{v} by the unit quaternion @var{q}. |
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22 ## Return a column vector. |
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23 ## |
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24 ## @example |
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25 ## vi = (2*real(q)^2 - 1)*vb + 2*imag(q)*(imag(q)'*vb) |
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26 ## + 2*real(q)*cross(imag(q),vb) |
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27 ## @end example |
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28 ## |
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29 ## @noindent |
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30 ## Where imag(q) is a column vector of length 3. |
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31 ## @end deftypefn |
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32 |
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33 ## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu> |
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34 ## Adapted-By: jwe |
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35 |
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36 function vi = qtransv (vb, qib) |
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37 |
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38 if (! isvector (vb) || length (vb) != 3) |
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39 error ("qtransv: v(%d,%d) must be a 3-D vector", rows (vb), columns (vb)); |
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40 elseif (! isvector (qib) || length (qib) != 4) |
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41 error ("qtransv: q(%d,%d) must be a quaternion", rows (qib), columns (qib)); |
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42 elseif (max (abs (imag (vb))) + max (abs (imag (qib))) != 0) |
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43 error ("qtransv: input values must be real"); |
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44 endif |
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45 |
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46 qr = qib(4); |
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47 qimag = vec (qib(1:3)); |
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48 vb = vec (vb); |
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49 vi = (2*qr^2 - 1)*vb + 2*qimag*(qimag'*vb) + 2*qr*cross (qimag, vb); |
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50 |
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51 endfunction |
