Generalized co-polynomials of $R_{II}$ type and associated quadrature rules (2304.11869v2)

Abstract: When the co-recursion and co-dilation in the recurrence relation of certain sequences of orthogonal polynomials are not at the same level, the behaviour of the modified orthogonal polynomials is expected to have different properties compared to the situation of the same level of perturbation. This manuscript attempts to derive structural relations between the perturbed and original $R_{II}$ type orthogonal polynomials. The classical result is improved using a transfer matrix approach. It turns out that the $R_{II}$ fraction with perturbation is the rational spectral transformation of the unperturbed one. The derived notions are used to deduce some consequences for the polynomials orthogonal on the real line. A natural question that arises while dealing with perturbations at different levels, i.e., which perturbation, co-recursion or co-dilation, needs to be performed first, is answered.