Generalized output nulling subspaces: Riccati equation computation and applications

Four generalized output-nulling subspaces (ONS) are defined and it is shown that many subspaces important in the analysis of linear systems can be expressed as special cases of the ONS. On the other hand, it is shown that the ONS can be computed from the solutions to square-root Riccati equations. Applications to computation of subspaces contained in the state space and applications to system inversion are demonstrated. The properties of the ONS considered as time-dependent subspace sequences are investigated.