Mercurial > forge
view main/quaternion/inst/@quaternion/diff.m @ 9892:8ad402be2313 octave-forge
main/quaternion --> extra/quaternion-legacy, extra/quaternion_oo --> main/quaternion
author | paramaniac |
---|---|
date | Wed, 28 Mar 2012 03:16:58 +0000 |
parents | extra/quaternion_oo/inst/@quaternion/diff.m@ada348c53379 |
children |
line wrap: on
line source
## Copyright (c) 1998, 2000, 2005, 2007 Auburn University. ## Copyright (c) 2011 Juan Pablo Carbajal <carbajal@ifi.uzh.ch> ## ## This program is free software: you can redistribute it and/or modify ## it under the terms of the GNU General Public License as published by ## the Free Software Foundation, either version 3 of the License, or ## (at your option) any later version. ## ## This program is distributed in the hope that it will be useful, ## but WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with this program. If not, see <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {@var{qdot} =} diff (@var{q}, @var{omega}) ## Derivative of a quaternion. ## ## Let Q be a quaternion to transform a vector from a fixed frame to ## a rotating frame. If the rotating frame is rotating about the ## [x, y, z] axes at angular rates [wx, wy, wz], then the derivative ## of Q is given by ## ## @example ## Q' = diff(Q, omega) ## @end example ## ## If the passive convention is used (rotate the frame, not the vector), ## then ## ## @example ## Q' = diff(Q,-omega) ## @end example ## @end deftypefn ## Adapted from: qderiv by A. S. Hodel <a.s.hodel@eng.auburn.edu> function qd = diff (q, Omega) if (nargin != 2) print_usage (); endif if (! isa (q, "quaternion") || ! isscalar (q.w)) error ("quaternion: first argument '%s' must be a scalar quaternion", inputname(1)); endif Omega = vec (Omega); if (length (Omega) != 3) error ("quaternion: second argument '%s' must be a length 3 vector", inputname(2)); endif qd = 0.5 * quaternion (Omega(1), Omega(2), Omega(3)) * q; endfunction %!shared q %! q = quaternion(3,1,0,0); %!assert(quaternion(0,0,0.5,1.5) == diff(q,[0 0 1])) %!assert(quaternion(0,0,2,1) == diff(q,[0 1 1]))