def check_case(self, a, b, q, r):
x = solve_continuous_are(a, b, q, r)<EOL>assert_array_almost_equal(<EOL>a.getH()*x + x*a - x*b*inv(r)*b.getH()*x + q, <NUM_LIT:0.0>)<EOL>
Checks if (A'X + XA - XBR^-1B'X+Q=0) is true