1 | function q = plus(l, r) |
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2 | % + Plus. |
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3 | % (Quaternion overloading of standard Matlab function.) |
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4 | |
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5 | % Copyright © 2005 Stephen J. Sangwine and Nicolas Le Bihan. |
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6 | % See the file : Copyright.m for further details. |
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7 | |
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8 | error(nargchk(2, 2, nargin)), error(nargoutchk(0, 1, nargout)) |
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9 | |
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10 | % Three cases have to be handled: |
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11 | % |
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12 | % l is a quaternion, r is not, |
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13 | % r is a quaternion, l is not, |
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14 | % l and r are both quaternions. |
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15 | % |
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16 | % The complication here is that we can't call ispure() or s() etc |
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17 | % for a parameter that is not a quaternion, so we have to handle |
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18 | % these cases differently. |
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19 | |
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20 | if isa(l, 'quaternion') & isa(r, 'quaternion') |
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21 | |
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22 | % The scalar part could be empty, and we have to handle this |
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23 | % specially, because [] + x is [] and not x, for some reason. |
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24 | |
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25 | if ispure(l) & ispure(r) |
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26 | q = quaternion( x(l) + x(r), y(l) + y(r), z(l) + z(r)); |
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27 | elseif ispure(l) |
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28 | q = quaternion( s(r), x(l) + x(r), y(l) + y(r), z(l) + z(r)); |
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29 | elseif ispure(r) |
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30 | q = quaternion(s(l), x(l) + x(r), y(l) + y(r), z(l) + z(r)); |
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31 | else |
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32 | q = quaternion(s(l) + s(r), x(l) + x(r), y(l) + y(r), z(l) + z(r)); |
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33 | end |
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34 | |
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35 | elseif isa(l, 'quaternion') & isa(r, 'numeric') |
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36 | |
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37 | if ispure(l) |
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38 | q = quaternion( r, x(l), y(l), z(l)); |
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39 | else |
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40 | q = quaternion(s(l) + r, x(l), y(l), z(l)); |
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41 | end |
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42 | |
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43 | elseif isa(l, 'numeric') & isa(r, 'quaternion') |
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44 | |
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45 | if ispure(r) |
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46 | q = quaternion(l , x(r), y(r), z(r)); |
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47 | else |
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48 | q = quaternion(l + s(r), x(r), y(r), z(r)); |
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49 | end |
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50 | |
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51 | else |
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52 | error('Unhandled parameter types in function +/plus') |
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53 | end |
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54 | |
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55 | |
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