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Article #195A question about Nevallina-Pick theory
From: Onur Toker
Date: Wed, 27 Jan 1993 01:43
Date: Wed, 27 Jan 1993 01:43
22 lines
1664 bytes
1664 bytes
Let m(z) be an inner function defined on the unit disc D, and let z_1,...,z_n be finitely many points on D. It is known that there exists a rational inner function m_f(z) which interpolates m(z) at z_1,..,z_n (This is a classical result in Nevallina-Pick interpolation theory). My question is about the parametrization of all such m_f's? Does anybody know anything about (1) parametrization of all such m_f's? (2) given N, is there an m_f of order N? Remarks: The parametrization of all analytic functions with norm <= 1 and satisfying the above interpolation conditions is known. Furthermore if we know the definition of the function m(z) and the numerical values of points z_1,...,z_n then question (2) can be answered by reducing it to a linear algebra problem and checking whether a system of equations has a solution or not. But I don't know whether (2) holds for all sufficently large N values (or for N > 2*n). O.Toker
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Path: arc1-ca.pugleaf.net!sparky!uunet!ogicse!usenet.coe.montana.edu!saimiri.primate.wisc.edu!sdd.hp.com!ux1.cso.uiuc.edu!news.cso.uiuc.edu!dan From: tokero@bode.eng.ohio-state.edu (Onur Toker) Newsgroups: sci.math.research Subject: A question about Nevallina-Pick theory Message-ID: <1993Jan27.014313.19660@ee.eng.ohio-state.edu> Date: 27 Jan 93 01:43:13 GMT Article-I.D.: ee.1993Jan27.014313.19660 Sender: Daniel Grayson <dan@math.uiuc.edu> Organization: The Ohio State University Dept of Electrical Engineering Lines: 22 Approved: Daniel Grayson <dan@math.uiuc.edu> Originator: dan@symcom.math.uiuc.edu X-Submissions-To: sci-math-research@uiuc.edu X-Administrivia-To: sci-math-research-request@uiuc.edu