MPOWER Raise quaternion to integer power Compound the quaternion with itself. Invoked by means of the caret operator.
0001 %MPOWER Raise quaternion to integer power 0002 % 0003 % Compound the quaternion with itself. Invoked by means of the caret 0004 % operator. 0005 0006 % Copyright (C) 1999-2008, by Peter I. Corke 0007 % 0008 % This file is part of The Robotics Toolbox for Matlab (RTB). 0009 % 0010 % RTB is free software: you can redistribute it and/or modify 0011 % it under the terms of the GNU Lesser General Public License as published by 0012 % the Free Software Foundation, either version 3 of the License, or 0013 % (at your option) any later version. 0014 % 0015 % RTB is distributed in the hope that it will be useful, 0016 % but WITHOUT ANY WARRANTY; without even the implied warranty of 0017 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 0018 % GNU Lesser General Public License for more details. 0019 % 0020 % You should have received a copy of the GNU Leser General Public License 0021 % along with RTB. If not, see <http://www.gnu.org/licenses/>. 0022 0023 function qp = mpower(q, p) 0024 0025 % check that exponent is an integer 0026 if (p - floor(p)) ~= 0, 0027 error('quaternion exponent must be integer'); 0028 end 0029 0030 qp = q; 0031 0032 % multiply by itself so many times 0033 for i = 2:abs(p), 0034 qp = qp * q; 0035 end 0036 0037 % if exponent was negative, invert it 0038 if p<0, 0039 qp = inv(qp); 0040 end