Christoffel Transform and Multiple Orthogonal Polynomials

Fuente: arXiv
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Autori principali: Kozhan, Rostyslav, Vaktnäs, Marcus
Natura: Preprint
Pubblicazione: 2024
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author Kozhan, Rostyslav
Vaktnäs, Marcus
author_facet Kozhan, Rostyslav
Vaktnäs, Marcus
contents We investigate multiple orthogonal polynomials associated with the system of measures obtained by applying a Christoffel transform to each of the orthogonality measures. We present an algorithm for computing the transformed recurrence coefficients and determinantal formulas for the transformed multiple orthogonal polynomials of type I and type II. We apply these results to show that zeros of multiple orthogonal polynomials of an Angelesco or an AT system interlace with the zeros of the polynomials corresponding to its one-step Christoffel transform. This allows us to prove a number of interlacing properties satisfied by the multiple orthogonality analogues of classical orthogonal polynomials. For the discrete polynomials, this also produces an estimate on the smallest distance between consecutive zeros. We also identify a connection between the Christoffel transform of orthogonal polynomials and multiple orthogonality systems containing a finitely supported measure. In consequence, the compatibility relations for the nearest neighbour recurrence coefficients provide a new algorithm for the computation of the Jacobi coefficients of the one-step or multi-step Christoffel transforms.
format Preprint
id arxiv_https___arxiv_org_abs_2407_13946
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Christoffel Transform and Multiple Orthogonal Polynomials
Kozhan, Rostyslav
Vaktnäs, Marcus
Classical Analysis and ODEs
42C05, 47B36, 65Q30
We investigate multiple orthogonal polynomials associated with the system of measures obtained by applying a Christoffel transform to each of the orthogonality measures. We present an algorithm for computing the transformed recurrence coefficients and determinantal formulas for the transformed multiple orthogonal polynomials of type I and type II. We apply these results to show that zeros of multiple orthogonal polynomials of an Angelesco or an AT system interlace with the zeros of the polynomials corresponding to its one-step Christoffel transform. This allows us to prove a number of interlacing properties satisfied by the multiple orthogonality analogues of classical orthogonal polynomials. For the discrete polynomials, this also produces an estimate on the smallest distance between consecutive zeros. We also identify a connection between the Christoffel transform of orthogonal polynomials and multiple orthogonality systems containing a finitely supported measure. In consequence, the compatibility relations for the nearest neighbour recurrence coefficients provide a new algorithm for the computation of the Jacobi coefficients of the one-step or multi-step Christoffel transforms.
title Christoffel Transform and Multiple Orthogonal Polynomials
topic Classical Analysis and ODEs
42C05, 47B36, 65Q30
url https://arxiv.org/abs/2407.13946