Approximation Properties of the Vallée-Poussin Means of Partial Sums of a Special Series in Laguerre Polynomials

Mathematical Notes - We consider the problem of the approximation of functions, continuous on the semiaxis $$[0,\infty)$$ and for which the derivatives $$f^{(\nu)}(0)$$ , $$\nu=0,\dots,r-1$$ exist...     

Estimate of the Lebesgue Function of Fourier Sums in Terms of Modified Meixner Polynomials

Mathematical Notes - The paper is devoted to the study of the approximation properties of Fourier sums in terms of the modified Meixner polynomials m (x), n = 0,1,..., which generate, for α...     

On Approximation Properties of Fourier Series in Jacobi Polynomials $$P_n^{\alpha-r,-r}(x)$$ Orthogonal in the Sense of Sobolev

Mathematical Notes - The article deals with the problem of the deviation from a function $$f$$ belonging to the space $$W^r$$ of partial sums of Fourier series with respect to the system of...