Extensions of Walsh's equiconvergence theorem for Jordan domains with analytic boundary curve (Q1280256)
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scientific article; zbMATH DE number 1261144
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | Extensions of Walsh's equiconvergence theorem for Jordan domains with analytic boundary curve |
scientific article; zbMATH DE number 1261144 |
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Extensions of Walsh's equiconvergence theorem for Jordan domains with analytic boundary curve (English)
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14 March 1999
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The author proves among others a generalization of Walsh's equiconvergence theorem. Theorem 1. Let \(\partial E\) be an \(r_0\)-analytic curve for some \(r_0\in [0,1)\), let \(f\) be a holomorphic function in \(G_R\) for some \(R>1\), and let \(L_n\) and \(L^*_n\) denote the Lagrange interpolatory polynomials of \(f\) in the \((n+1)\)-st Fejér nodes and Faber nodes on \(E\), respectively. Then \[ \lim_{n\to\infty} [L_n(z)-L^*_n(z)]=0 \qquad (z\in G_\lambda), \] the convergence being uniform and geometric on every subset \(\overline G_\mu\) for \(1\leq \mu<\lambda\), where \[ \lambda :=\min \{R^2 ,R/r_0\}. \]
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Walsh's equiconvergence theorem
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Fejér nodes
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Faber nodes
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