function	check_dcnots(vecs)



%Input is a matrix packed with 2 rows of unit 3d vectors.

%Input specifies a string of dressed cnots.

%This function checks that all the input vectors are unit vectors.



cols = columns(vecs);

if(rows(vecs)!=6)

	error("input doesn't have six rows.");

end

for c=1:cols

	r=1;

	while(r<5)

		if(abs(norm(vecs(r:r+2,c))-1)>1e-10)

			error("non-unit vector used to specify a dressed cnot");

		end

		r=r+3;

	end

end