Kalle M. Mikkola

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It is known that a matrix-valued transfer function P has a stabilizing dynamic controller Q (i.e., h I −Q −P I i −1 ∈ H ∞) iff P has a right (or left) coprime factorization. We show that the same result is true in the operator-valued case. Thus, the standard Youla–Bongiorno parameteriza-tion applies to every dynamically stabilizable function. We then derive(More)
During the past decades much of finite-dimensional systems theory has been generalized to infinite dimensions. However, there is one important flaw in this theory: it only guarantees complex solutions, even when the data is real. We show that the standard solutions of many classical problems with real data are also real. We call a (possibly matrix-or(More)
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