function a = abs(q)
% ABS Absolute value, or modulus, of a quaternion.
% (Quaternion overloading of standard Matlab function.)

% 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)) 

a = sqrt(modsquared(q));