16 research outputs found

    Fine Structure of the Zeros of Orthogonal Polynomials, II. OPUC With Competing Exponential Decay

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    We present a complete theory of the asymptotics of the zeros of OPUC with Verblunsky coefficients αn==1LCbn+O((bΔ)n)\alpha_n = \sum_{\ell=1}^L C_\ell b_\ell^n + O((b\Delta)^n) where Δ<1\Delta <1 and \abs{b_\ell} = b<1.Comment: Keywords: orthogonal polynomials, Jacobi matrices, CMV matrice

    Fine Structure of the Zeros of Orthogonal Polynomials: A Review

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    We review recent work on zeros of orthogonal polynomials

    Meromorphic Szego functions and asymptotic series for Verblunsky coefficients

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    We prove that the Szeg\H{o} function, D(z)D(z), of a measure on the unit circle is entire meromorphic if and only if the Verblunsky coefficients have an asymptotic expansion in exponentials. We relate the positions of the poles of D(z)1D(z)^{-1} to the exponential rates in the asymptotic expansion. Basically, either set is contained in the sets generated from the other by considering products of the form, z1...zzˉ1...zˉ21z_1 ... z_\ell \bar z_{\ell-1}... \bar z_{2\ell-1} with zjz_j in the set. The proofs use nothing more than iterated Szeg\H{o} recursion at zz and 1/zˉ1/\bar z

    Fine structure of the zeros of orthogonal polynomials III: Periodic recursion coefficients

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    We discuss asymptotics of the zeros of orthogonal polynomials on the real line and on the unit circle when the recursion coefficients are periodic. The zeros on or near the absolutely continuous spectrum have a clock structure with spacings inverse to the density of zeros. Zeros away from the a.c. spectrum have limit points mod p and only finitely many of them

    OPUC on One Foot

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    We present an expository introduction to orthogonal polynomials on the unit circle
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