Determinantal Formulas for Rational Perturbations of Multiple Orthogonality Measures

Fuente: arXiv
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Main Authors: Kozhan, Rostyslav, Vaktnäs, Marcus
Format: Preprint
Published: 2024
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author Kozhan, Rostyslav
Vaktnäs, Marcus
author_facet Kozhan, Rostyslav
Vaktnäs, Marcus
contents Given multiple orthogonal polynomials on the real line with respect to a system $\bmμ = (μ_1,\ldots,μ_r)$, we investigate multiple orthogonal polynomials associated with any rational perturbation of the form $$ \widetilde{\bmμ}=\Big(\frac{Φ_1}{Ψ_{1}} μ_1,\dots,\frac{Φ_r}{Ψ_r}μ_r\Big), $$ for any polynomials $Φ_1,\dots,Φ_r$ and $Ψ_1,\dots,Ψ_r$. We derive the analogues of Uvarov's determinantal formula for the multiple orthogonal polynomials of type I and type II for $\widetilde{\bmμ}$ and establish necessary and sufficient condition for normality of the indices. The result allows the polynomials $\{Φ_j,Ψ_j\}_{j=1}^r$ to be arbitrary and permits the addition of finitely many point masses to each of the measures $μ_j$. Moreover, the measures $μ_j$ may be taken as quasi-definite linear functionals, which is of interest even in the case $r=1$.
format Preprint
id arxiv_https___arxiv_org_abs_2407_13961
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Determinantal Formulas for Rational Perturbations of Multiple Orthogonality Measures
Kozhan, Rostyslav
Vaktnäs, Marcus
Classical Analysis and ODEs
42C05, 41A21, 41A28
Given multiple orthogonal polynomials on the real line with respect to a system $\bmμ = (μ_1,\ldots,μ_r)$, we investigate multiple orthogonal polynomials associated with any rational perturbation of the form $$ \widetilde{\bmμ}=\Big(\frac{Φ_1}{Ψ_{1}} μ_1,\dots,\frac{Φ_r}{Ψ_r}μ_r\Big), $$ for any polynomials $Φ_1,\dots,Φ_r$ and $Ψ_1,\dots,Ψ_r$. We derive the analogues of Uvarov's determinantal formula for the multiple orthogonal polynomials of type I and type II for $\widetilde{\bmμ}$ and establish necessary and sufficient condition for normality of the indices. The result allows the polynomials $\{Φ_j,Ψ_j\}_{j=1}^r$ to be arbitrary and permits the addition of finitely many point masses to each of the measures $μ_j$. Moreover, the measures $μ_j$ may be taken as quasi-definite linear functionals, which is of interest even in the case $r=1$.
title Determinantal Formulas for Rational Perturbations of Multiple Orthogonality Measures
topic Classical Analysis and ODEs
42C05, 41A21, 41A28
url https://arxiv.org/abs/2407.13961