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JOURNALS // Izvestiya of Saratov University. Mathematics. Mechanics. Informatics // Archive

Izv. Saratov Univ. Math. Mech. Inform., 2018 Volume 18, Issue 1, Pages 17–24 (Mi isu741)

This article is cited in 2 papers

Scientific Part
Mathematics

Recurrence relations for polynomials orthonormal on Sobolev, generated by Laguerre polynomials

R. M. Gadzhimirzaev

Dagestan Scientific Center, Russian Academy of Sciences, 45, Gadjieva Str., Makhachkala, Russia, 367025

Abstract: In this paper we consider the system of polynomials $l_{r,n}^{\alpha}(x)$ ($r$ — natural number, $n=0, 1, \ldots$), orthonormal with respect to the Sobolev inner product (Sobolev orthonormal polynomials) of the following type $\langle f,g\rangle=\sum_{\nu=0}^{r-1}f^{(\nu)}(0)g^{(\nu)}(0)+\int_{0}^{\infty} f^{(r)}(t)g^{(r)}(t)\rho(t)\,dt$ and generated by the classical orthonormal Laguerre polynomials. Recurrence relations are obtained for the system of Sobolev orthonormal polynomials, which can be used for studying various properties of these polynomials and calculate their values for any $x$ and $n$. Moreover, we consider the system of the Laguerre functions $\mu_{n}^{\alpha}(x) = \sqrt{\rho(x)}l_{n}^{\alpha}(x)$, which generates a system of functions $\mu_{r, n}^{\alpha}(x)$ orthonormal with respect to the inner product of the following form $\langle \mu_{r,n}^\alpha,\mu_{r,k}^\alpha\rangle= \sum_{\nu=0}^{r-1}(\mu_{r,n}^\alpha(x))^{(\nu)}|_{x=0} (\mu_{r,k}^\alpha(x))^{(\nu)}|_{x=0}+ \int_{0}^{\infty} (\mu_{r,n}^\alpha(x))^{(r)}(\mu_{r,k}^\alpha(x))^{(r)}\,dx.$ For the generated system of functions $\mu_{r,n}^{\alpha}(x)$, recurrence relations for $\alpha=0$ are also obtained.

Key words: Laguerre polynomials, Sobolev-type inner product, Sobolev orthonormal polynomials, Laguerre functions.

UDC: 517.15

DOI: 10.18500/1816-9791-2018-18-1-17-24



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