Results 11 to 20 of about 264 (60)
On the approximation by trigonometric polynomials in weighted Lorentz spaces
Journal of Function Spaces, Volume 8, Issue 1, Page 67-86, 2010., 2010 We obtain estimates of structural characteristics of 2π‐periodic functions by the best trigonometric approximations in weighted Lorentz spaces, and show that the order of generalized modulus of smoothness depends not only on the rate of the best approximation, but also on the metric of the spaces.
Vakhtang Kokilashvili +2 more
wiley +1 more source
Stečkin inequalities for summability methods
International Journal of Mathematics and Mathematical Sciences, Volume 20, Issue 1, Page 93-100, 1997., 1995 Stečkin proved an inequality on Fejér means of Fourier series He said, “Proving similar inequality for other summability method is an interesting problem.” We generalize Stečkin′s inequality and give various applications to summability methods.
Jia-Ding Cao
wiley +1 more source
On approximations by trigonometric polynomials of classes of functions defined by moduli of smoothness [PDF]
, 2017 In this paper, we give a characterization of Nikol'ski\u{\i}-Besov type classes of functions, given by integral representations of moduli of smoothness, in terms of series over the moduli of smoothness.
Berisha, Faton M. +3 more
core +3 more sources
Rigorous numerics for nonlinear operators with tridiagonal dominant linear part [PDF]
, 2015 We present a method designed for computing solutions of infinite dimensional non linear operators $f(x) = 0$ with a tridiagonal dominant linear part. We recast the operator equation into an equivalent Newton-like equation $x = T(x) = x - Af(x)$, where $A$
Breden, Maxime +2 more
core +2 more sources
On approximation in generalized Zygmund class
Demonstratio Mathematica, 2019 Here, we estimate the degree of approximation of a conjugate function g˜{\tilde g} and a derived conjugate function g˜′{\tilde g'} , of a 2π-periodic function g∈Zrλg \in Z_r^\lambda , r ≥ 1, using Hausdorff means of CFS (conjugate Fourier series) and
Nigam Hare Krishna
doaj +1 more source
On the Lebesgue constant of the trigonometric Floater-Hormann rational interpolant at equally spaced nodes [PDF]
, 2019 It is well known that the classical polynomial interpolation gives bad approximation if the nodes are equispaced. A valid alternative is the family of barycentric rational interpolants introduced by Berrut in [4], analyzed in terms of stability by Berrut
Bandiziol, Cinzia, DE MARCHI, STEFANO
core +1 more source
, 2014 In this paper, we discuss various properties of the new modulus of smoothness \[ \omega^\varphi_{k,r}(f^{(r)},t)_p := \sup_{0 < h\leq t}\|\mathcal W^r_{kh}(\cdot) \Delta_{h\varphi(\cdot)}^k (f^{(r)},\cdot)\|_{L_p[-1,1]}, \] where $\mathcal W_\delta(x) = \
Kopotun, K. A. +2 more
core +1 more source
Determinate multidimensional measures, the extended Carleman theorem and quasi-analytic weights [PDF]
, 2002 We prove in a direct fashion that a multidimensional probability measure is determinate if the higher dimensional analogue of Carleman's condition is satisfied.
de Jeu, Marcel
core +4 more sources
An extension of a theorem of Schoenberg to products of spheres
, 2015 We present a characterization for the continuous, isotropic and positive definite kernels on a product of spheres along the lines of a classical result of I. J. Schoenberg on positive definiteness on a single sphere.
Guella, J. C. +2 more
core +1 more source
A mathematical theory of super-resolution and two-point resolution
Forum of Mathematics, SigmaThis paper focuses on the fundamental aspects of super-resolution, particularly addressing the stability of super-resolution and the estimation of two-point resolution. Our first major contribution is the introduction of two location-amplitude identities
Ping Liu, Habib Ammari
doaj +1 more source