On the stability of the convex combinations of the stable irrational polynomials

The method given in E. Zeheb, 'Necessary and sufficient conditions for root clustering of a polytope of polynomials in a simply connected domain' IEEE Transactions on Automatic Control, Volume AC-34, No. 5, pp. 544-546, 1989, is extended to certain distributed parameter systems in order to check the stability of convex combinations of the irrational polynomials. Illustrative examples are included.<
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