State Space Formulas for a Solution of the Suboptimal Nehari Problem on the Unit Disc

Abstract.

We give state space formulas for a (“central”) solution of the suboptimal Nehari problem for functions defined on the unit disc and taking values in the space of bounded operators in separable Hilbert spaces. Instead of assuming exponential stability, we assume a weaker stability concept (the combination of input-, output- and input-output stability), which allows us to solve the problem for general H-infinity functions.