English

On the leading coefficient of polynomials orthogonal over domains with corners

Classical Analysis and ODEs 2023-01-24 v1

Abstract

Let GG be the interior domain of a piecewise analytic Jordan curve without cusps. Let {pn}n=0\{p_n\}_{n=0}^\infty be the sequence of polynomials that are orthonormal over GG with respect to the area measure, with each pnp_n having leading coefficient λn>0\lambda_n>0. N. Stylianopoulos has recently proven that the asymptotic behavior of λn\lambda_n as nn\to\infty is given by n+1πγ2n+2λn2=1αn, \frac{n+1}{\pi}\frac{\gamma^{2n+2}}{ \lambda_n^{2}}=1-\alpha_n, where αn=O(1/n)\alpha_n=O(1/n) as nn\to\infty and γ\gamma is the reciprocal of the logarithmic capacity of the boundary G\partial G. In this paper, we prove that the O(1/n)O(1/n) estimate for the error term αn\alpha_n is, in general, best possible, by exhibiting an example for which lim infnnαn>0. \liminf_{n\to\infty}\,n\alpha_n>0. The proof makes use of the Faber polynomials, about which a conjecture is formulated.

Keywords

Cite

@article{arxiv.1407.5061,
  title  = {On the leading coefficient of polynomials orthogonal over domains with corners},
  author = {Erwin Miña-Díaz},
  journal= {arXiv preprint arXiv:1407.5061},
  year   = {2023}
}

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7 pages