function r = z(q)
% Z  Extracts the z component of the vector part of a quaternion.

% Copyright © 2005 Stephen J. Sangwine and Nicolas Le Bihan.
% See the file : Copyright.m for further details.

% error(nargchk(1, 1, nargin)), error(nargoutchk(0, 1, nargout))

% This function is written in terms of its private counterpart
% so that the underlying representation of a quaternion is a
% private aspect of the class.

r = zed(q);