% -*- texinfo -*-
% @deftypefn {Function File} {} qderiv (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' = qderivmat (omega) * Q
% @end example
%
% If the passive convention is used (rotate the frame, not the vector),
% then
%
% @example
% Q' = -qderivmat (omega) * Q
% @end example
% @end deftypefn