samer@4: function z=issym(x,th)
samer@4: % issym - Test if matrix is symmetric with optional tolerance
samer@4: %
samer@4: % issym :: [[N,N]] -> bool.
samer@4: % issym :: [[N,N]], nonneg -> bool.
samer@4: 
samer@4: if nargin<2,
samer@4: 	z=all(all(x==x'));
samer@4: else
samer@4: 	z=all(all(abs(x-x')<=th));
samer@4: end