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%Van Dooren
%Paul","paul.vandooren@uclouvain.be","
\section{H2 approximation of linear dynamical systems} By {\sl P. Van Dooren, K. Gallivan and P.A. Absil}.  

\medskip  \noindent  We consider the problem of approximating an $m\times p$ rational transfer function $H(s)$ of high degree by another $m\times p$ rational transfer function $\hat H(s)$ of much smaller degree. We derive the gradients
 of the ${\cal H}_2$-norm of the approximation error and show how this can be solved  via tangential interpolation. We then extend these results to the discrete-time case, for both time-invariant and time-varying systems.
%Tangential interpolation, H2 approximation, model reduction","15","65","","09:41:21","Tue Feb 19 2008","130.104.239.210"
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