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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb. (N.S.), 1979 Volume 109(151), Number 1(5), Pages 46–59 (Mi sm2353)

This article is cited in 14 papers

The asymptotic behavior of orthogonal polynomials

V. M. Badkov


Abstract: Let $\{\varphi_{\sigma,n}(z)\}_{n=0}^\infty$ be the system of polynomials orthonormal on the unit circumference with respect to the measure $\sigma$. By way of generalizing and strengthening a number of previous results, we show that if $\ln\sigma'(\theta)\in L^1[0,2\pi]$, $\sigma'(\theta)$ continuous and positive on $[a,b]\subset[0,2\pi]$, and $\omega(\sigma';\tau)_{[a,b]}\tau^{-1}\in L^1[0,b-a]$, then the polynomials $\varphi_{\sigma,n}^*(e^{i\theta})=e^{in\theta}\overline{\varphi_{\sigma,n}(e^{i\theta})}$ converge uniformly in $\theta$, inside $(a,b)$, to the Szegö function. The result so formulated is shown to be definitive.
Bibligraphy: 16 titles.

UDC: 517.512

MSC: 42C05

Received: 03.08.1978


 English version:
Mathematics of the USSR-Sbornik, 1980, 37:1, 39–51

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