  function u = SkewSchur3(x,y,z)
% x,y,z are real scalars not all zero. 
% u is a unit 2-norm 3-vector with the property
% that if A = [0 x y ; -x 0 z; -y -z 0] and Q = I - 2uu' then
% Q'*A*Q = [0 0 0 ; 0 0 tau ; 0 -tau 0]
 
 
    