function X = care_schur(A, G, Q)
H = [A -G; -Q -A'];
[U, T] = schur(H, 'complex');
[U2, T2] = ordschur(U, T, 'lhp');
n = size(A,1);
X = U2(n+1:2*n, 1:n) / U2(1:n, 1:n);