0, 2, 1], [5, 2, 6, 6], [4, 7, 7, 7]]) >>> AA, BB, alpha, beta, Q, Z = ordqz(A, B, sort='lhp') Since we have sorted for left half plane eigenvalues, negatives come first >>> (alpha/beta).real < 0 array([ True, True, False, False], dtype=bool) N)