function tf = isreal(A)
% ISREAL True for real (quaternion) array.
% (Quaternion overloading of standard Matlab function.)

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

% This function returns true if all the components of A are real, that is,
% A is a quaternion with real coefficients (a real quaternion).

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

if ispure(A)
    tf = isreal(x(A)) & isreal(y(A)) & isreal(z(A));
else
    tf = isreal(s(A)) & isreal(v(A));
end