Block-diagonalization and block-triangularization of a matrix via the matrix sign function
Leang San Shieh, YIH TSONG TSAY, Shih-Wei Lin, Norman P. Coleman · International Journal of Systems Science · 1984
A matrix sign function in conjunction with a geometric approach is utilized to construct a block modal matrix and a (scalar) modal matrix of a system map, so that the system map can be block-diagonalized and block-triangularized, and that the Riccati-type problems can be solved.