[U,T] = SCHUR(X) produces a Schur matrix T and a unitary
matrix U so that X = U*T*U' and U'*U = EYE (U).
By itself, SCHUR(X) returns T.
If X is complex, the Complex Schur Form is returned in matrix T.
The Complex Schur Form is upper triangular with the eigenvalues
of X on the diagonal.
If X is real, the Real Schur Form is returned. The Real Schur
Form has the real eigenvalues on the diagonal and the complex
eigenvalues in 2-by-2 blocks on the diagonal.
See RSF2CSF to convert from Real to Complex Schur form.