Title of article
A Cohen type inequality for Laguerre--Sobolev expansions with a mass point outside their oscillatory regime
Author/Authors
CEJUDO, EDMUNDO JOSÉ HUERTAS University of Coimbra - Center for Mathematics - Department of Mathematics, Portugal , MARCELLÁN ESPANOL, FRANCISCO Charles III University of Madrid - Institute of Mathematical Sciences - Department of Mathematics, Spain , VALERO, MARÍA FRANCISCA PÉREZ Carlos III University of Madrid - Department of Mathematisc, Spain , QUINTANA, YAMILET Simon Bolivar University - Department of Pure and Applied Mathematics, Venezuela
From page
994
To page
1006
Abstract
Let consider the Sobolev type inner product langle f, grangle_S = int_0^{infty} f(x)g(x)d mu (x) + Mf(c)g(c) + Nf^{prime}(c) g^{prime}(c), where dmu (x) = x^{alpha} e^{-x}dx, alpha -1, is the Laguerre measure, c 0, and M, N geq 0. In this paper we get a Cohen-type inequality for Fourier expansions in terms of the orthonormal polynomials associated with the above Sobolev inner product. Then, as an immediate consequence, we deduce the divergence of Fourier expansions and Cesàro means of order delta in terms of this kind of Laguerre--Sobolev polynomials.
Keywords
Sobolev , type orthogonal polynomials , Cohen , type inequality , Fourier , , Sobolev expansions
Journal title
Turkish Journal of Mathematics
Journal title
Turkish Journal of Mathematics
Record number
2531521
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