Asymptotic Distribution of the Zeros of recursively defined Non-Orthogonal Polynomials

Bernhard Heim; Markus Neuhauser

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arXiv · 2107.05013

Asymptotic Distribution of the Zeros of recursively defined Non-Orthogonal Polynomials

Bernhard Heim·Markus Neuhauser

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Abstract

We study the zero distribution of non-orthogonal polynomials attached to $g(n)=s(n)=n^2$: \begin{equation*} Q_n^g(x)= x \sum_{k=1}^n g(k) \, Q_{n-k}^g(x), \quad Q_0^g(x):=1. \end{equation*} It is known that the case $g=id$ involves Chebyshev polynomials of the second kind. The zeros of $Q_n^s(x)$ are real, simple, and are located in $(-6\sqrt{3},0]$. Let $N_n(a,b)$ be the number of zeros between $-6 \sqrt{3} \leq a < b \leq 0$. Then we determine a density function $v(x)$, such that \begin{equation*} \lim_{n \rightarrow \infty} \frac{N_n(a,b)}{n} = \int_a^b v(x) \,\, \mathrm{d}x. \end{equation*} The polynomials $Q_n^s(x)$ satisfy a four-term recursion. We present in detail an analysis of the fundamental roots and give an answer to an open question on recent work by Adams and Tran--Zumba. We extend a method proposed by Freud for orthogonal polynomials to more general systems of polynomials. We determine the underlying moments and density function for the zero distribution.

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BibTeX RIS

Bernhard Heim, Markus Neuhauser. 2021-07-11. Asymptotic Distribution of the Zeros of recursively defined Non-Orthogonal Polynomials. https://arxiv.org/abs/2107.05013

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