Some examples of orthogonal matrix polynomials satisfying odd order differential equations

It is well known that if a finite order linear differential operator with polynomial coefficients has as eigenfunctions a sequence of orthogonal polynomials with respect to a positive measure (with support in the real line), then its order has to be even. This property no longer holds in the case of...

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Bibliographic Details
Authors: Durán Guardeño, Antonio José, Iglesia, Manuel D. de la
Format: article
Status:Published version
Publication Date:2007
Country:España
Institution:Universidad de Sevilla (US)
Repository:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/182613
Online Access:https://hdl.handle.net/11441/182613
https://doi.org/10.1016/j.jat.2007.08.001
Access Level:Open access
Keyword:Orthogonal matrix polynomials
Differential equations
Algebra of differential operators
Description
Summary:It is well known that if a finite order linear differential operator with polynomial coefficients has as eigenfunctions a sequence of orthogonal polynomials with respect to a positive measure (with support in the real line), then its order has to be even. This property no longer holds in the case of orthogonal matrix polynomials. The aim of this paper is to present examples of weight matrices such that the corresponding sequences of matrix orthogonal polynomials are eigenfunctions of certain linear differential operators of odd order. The weight matrices are of the form W(t) = tae-teAttBtB*eA*t, where A and B are certain (nilpotent and diagonal, respectively) N X N matrices. These weight matrices are the first examples illustrating this new phenomenon which are not reducible to scalar weights.