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

Izv. Saratov Univ. Math. Mech. Inform., 2016 Volume 16, Issue 3, Pages 310–321 (Mi isu650)

This article is cited in 14 papers

Mathematics

Sobolev orthogonal polynomials generated by Meixner polynomials

I. I. Sharapudinovabc, Z. D. Gadzhievaab

a Dagestan Scientific Center RAS
b Dagestan State Pedagogical University, 45, M.Gadzhieva st., 367032, Makhachkala, Russia
c Vladikavkaz Scientific Center RAS

Abstract: The problem of constructing Sobolev orthogonal polynomials $m _{r,n}^{\alpha}(x,q)$ $(n=0,1,\ldots)$, generated by classical Meixner's polynomials is considered. They can by defined using the following equalities $m_{r,k}^{\alpha}(x,q)={x^{[k]}\over k!}$, $x^{[k]}=x(x-1)\cdots(x-k+1)$, $k=0,1,\ldots,r-1$, $m_{r,k+r}^{\alpha}(x,q)=\frac{1}{(r-1)!}\sum\limits_{t=0}^{x-r}(x-1-t)^{[r-1]}m_{k}^{\alpha}(t,q)$, where $m_{k}^{\alpha}(t,q)$ denote Meixner's polynomial of degree $k$, orthonormal on $\Omega=\{0,1,\ldots\}$ with weight $\rho(x)=q^x\frac{\Gamma(x+\alpha+1)}{\Gamma(x+1)}(1-q)^{\alpha+1}$. Polynomials $m _{r,n}^{\alpha}(x,q)$, $(n=0,1,\ldots)$ are orthonormal on $\Omega=\{0,1,\ldots\}$ with respect to the inner product
$$ \langle m_{r,n}^{\alpha},m_{r,m}^{\alpha}\rangle= \sum\limits_{k=0}^{r-1}\Delta^km_{r,n}^{\alpha}(0,q)\Delta^km_{r,m}^{\alpha}(0,q)+ \sum\limits_{j=0}^{\infty}\Delta^rm_{r,n}^{\alpha}(j,q)\Delta^r m_{r,m}^{\alpha}(j,q)\rho(j). $$
For $m_{r,n}^{\alpha}(x,q)$ we obtain the explicit formula that contains the Ìeixner polynomial $M_{n}^{\alpha-r}(x,q)$:
$$ m_{r,k+r}^{\alpha}(x,q)=\big(\frac{q}{q-1}\big)^r\left\{h_{k}^{\alpha}(q)\right\}^{-1/2} \left[M_{k+r}^{\alpha-r}(x,q)-\sum\limits_{\nu=0}^{r-1}\frac{A_{r,k,\nu}x^{[\nu]}}{\nu!}\right], k=0,1,\ldots, $$
where $A_{r,k,\nu}=\Big({q-1\over q}\Big)^\nu \frac{\Gamma(k+\alpha+1)}{(k+r-\nu)!\Gamma(\nu-r+\alpha+1)}$, $M_n^\alpha(x,q)=\frac{\Gamma (n+\alpha+1)}{n!} \sum_{k=0}^n{n^{[k]}x^{[k]}\over \Gamma (k+\alpha+1)k!}\left(1-{1\over q}\right)^k$, $h_n^\alpha(q)= {n+\alpha\choose n}q^{-n}\Gamma(\alpha+1)$.

Key words: orthogonal Sobolev polynomial, Meixner polynomials orthogonal on the grid, approximation of discrete functions, mixed series in Meixner polinomials orthogonal on a uniform grid.

UDC: 517.587

DOI: 10.18500/1816-9791-2016-16-3-310-321



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