Explicit construction of matrix-valued orthogonal polynomials of arbitrary size

Fuente: arXiv
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Autore principale: Parisi, Ignacio Bono
Natura: Preprint
Pubblicazione: 2025
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author Parisi, Ignacio Bono
author_facet Parisi, Ignacio Bono
contents In this paper, we explicitly provide expressions for a sequence of orthogonal polynomials associated with a weight matrix of size $N$ constructed from a collection of scalar weights $w_{1}, \ldots, w_{N}$: $$W(x) = T(x)\operatorname{diag}(w_{1}(x), \ldots, w_{N}(x))T(x)^{\ast},$$ where $T(x)$ is a specific polynomial matrix. We provide sufficient conditions on the scalar weights to ensure that the weight matrix $W$ is irreducible. Furthermore, we give sufficient conditions on the scalar weights to ensure the constructed sequence of matrix orthogonal polynomials is an eigenfunction of a differential operator. We also study the Darboux transformations and bispectrality of the orthogonal polynomials in the particular case where the scalar weights are the classical weights of Jacobi, Hermite, and Laguerre. With these results, we construct a wide variety of bispectral matrix-valued orthogonal polynomials of arbitrary size, which satisfy a second-order differential equation.
format Preprint
id arxiv_https___arxiv_org_abs_2503_12529
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Explicit construction of matrix-valued orthogonal polynomials of arbitrary size
Parisi, Ignacio Bono
Classical Analysis and ODEs
Spectral Theory
33C45, 42C05, 34L05, 34L10
In this paper, we explicitly provide expressions for a sequence of orthogonal polynomials associated with a weight matrix of size $N$ constructed from a collection of scalar weights $w_{1}, \ldots, w_{N}$: $$W(x) = T(x)\operatorname{diag}(w_{1}(x), \ldots, w_{N}(x))T(x)^{\ast},$$ where $T(x)$ is a specific polynomial matrix. We provide sufficient conditions on the scalar weights to ensure that the weight matrix $W$ is irreducible. Furthermore, we give sufficient conditions on the scalar weights to ensure the constructed sequence of matrix orthogonal polynomials is an eigenfunction of a differential operator. We also study the Darboux transformations and bispectrality of the orthogonal polynomials in the particular case where the scalar weights are the classical weights of Jacobi, Hermite, and Laguerre. With these results, we construct a wide variety of bispectral matrix-valued orthogonal polynomials of arbitrary size, which satisfy a second-order differential equation.
title Explicit construction of matrix-valued orthogonal polynomials of arbitrary size
topic Classical Analysis and ODEs
Spectral Theory
33C45, 42C05, 34L05, 34L10
url https://arxiv.org/abs/2503.12529