Connecting Exceptional Orthogonal Polynomials of Different Kind

Abstract

The known asymptotic relations interconnecting Jacobi, Laguerre, and Hermite classical orthogonal polynomials are generalized to the corresponding exceptional orthogonal polynomials of codimension $m$. It is proved that $X_m$-Laguerre exceptional orthogonal polynomials of type I, II, or III can be obtained as limits of $X_m$-Jacobi exceptional orthogonal polynomials of the same type. Similarly, $X_m$-Hermite exceptional orthogonal polynomials of type III can be derived from $X_m$-Jacobi or $X_m$-Laguerre ones. The quadratic transformations expressing Hermite classical orthogonal polynomials in terms of Laguerre ones is also extended to even $X_{2m}$-Hermite exceptional orthogonal polynomials.