On computing the zeros of a class of Sobolev orthogonal polynomials

Fuente: arXiv
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Auteurs principaux: Mastronardi, Nicola, Van Barel, Marc, Vandebril, Raf, Van Dooren, Paul
Format: Preprint
Publié: 2025
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author Mastronardi, Nicola
Van Barel, Marc
Vandebril, Raf
Van Dooren, Paul
author_facet Mastronardi, Nicola
Van Barel, Marc
Vandebril, Raf
Van Dooren, Paul
contents A fast and weakly stable method for computing the zeros of a particular class of hypergeometric polynomials is presented. The studied hypergeometric polynomials satisfy a higher order differential equation and generalize Laguerre polynomials. The theoretical study of the asymptotic distribution of the spectrum of these polynomials is an active research topic. In this article we do not contribute to the theory, but provide a practical method to contribute to further and better understanding of the asymptotic behavior. The polynomials under consideration fit into the class of Sobolev orthogonal polynomials, satisfying a four--term recurrence relation. This allows computing the roots via a generalized eigenvalue problem. After condition enhancing similarity transformations, the problem is transformed into the computation of the eigenvalues of a comrade matrix, which is a symmetric tridiagonal modified by a rank--one matrix. The eigenvalues are then retrieved by relying on an existing structured rank based fast algorithm. Numerical examples are reported studying the accuracy, stability and conforming the efficiency for various parameter settings of the proposed approach.
format Preprint
id arxiv_https___arxiv_org_abs_2503_20567
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On computing the zeros of a class of Sobolev orthogonal polynomials
Mastronardi, Nicola
Van Barel, Marc
Vandebril, Raf
Van Dooren, Paul
Numerical Analysis
33C20, 65F15, 65F35
A fast and weakly stable method for computing the zeros of a particular class of hypergeometric polynomials is presented. The studied hypergeometric polynomials satisfy a higher order differential equation and generalize Laguerre polynomials. The theoretical study of the asymptotic distribution of the spectrum of these polynomials is an active research topic. In this article we do not contribute to the theory, but provide a practical method to contribute to further and better understanding of the asymptotic behavior. The polynomials under consideration fit into the class of Sobolev orthogonal polynomials, satisfying a four--term recurrence relation. This allows computing the roots via a generalized eigenvalue problem. After condition enhancing similarity transformations, the problem is transformed into the computation of the eigenvalues of a comrade matrix, which is a symmetric tridiagonal modified by a rank--one matrix. The eigenvalues are then retrieved by relying on an existing structured rank based fast algorithm. Numerical examples are reported studying the accuracy, stability and conforming the efficiency for various parameter settings of the proposed approach.
title On computing the zeros of a class of Sobolev orthogonal polynomials
topic Numerical Analysis
33C20, 65F15, 65F35
url https://arxiv.org/abs/2503.20567