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We derive the non-asymptotical non-uniform sharp error estimation for Bernstein's approximation of continuous function based on the modern probabilistic apparatus. We investigate also the convergence of derivative of these polynomials and…

Functional Analysis · Mathematics 2015-08-31 Eugene Ostrovsky , Leonid Sirota

In this note we study a quantitative version of Bernstein's approximation problem when the polynomials are dense in weighted spaces on the real line completing a result of S.~N.~Mergelyan (1960). We estimate in the logarithmic scale the…

Classical Analysis and ODEs · Mathematics 2022-11-28 Anna Kononova

We discuss approximation of extremal functions by polynomials in the weighted Bergman spaces $A^p_\alpha$ where $-1 < \alpha < 0$ and $-1 < \alpha < p-2$. We obtain bounds on how close the approximation is to the true extremal function in…

Complex Variables · Mathematics 2017-05-19 Timothy Ferguson

The purpose of this note is to compare various approximation methods as applied to the inverse of the Bessel function of the first kind, in a given domain of the complex plane.

Numerical Analysis · Mathematics 2018-01-11 D. S. Karachalios , I. V. Gosea , Q. Zhang , A. C. Antoulas

We establish sharp inequalities involving the incomplete Beta and Gamma functions. These inequalities arise in the approximation of generalized Bernstein functions by higher order Thorin-Bernstein functions. Furthermore, new properties of a…

Classical Analysis and ODEs · Mathematics 2024-09-05 Stamatis Koumandos , Henrik Laurberg Pedersen

The inversion problem for rational B\'ezier curves is addressed by using resultant matrices for polynomials expressed in the Bernstein basis. The aim of the work is not to construct an inversion formula but finding the corresponding value…

Numerical Analysis · Mathematics 2010-07-19 Ana Marco , José-Javier Martinez

In this paper, we give direct theorems on point wise and global approximation by new variants of Bernstein-Durrmeyer operator, introduced by A.-M. et al.[1].

Classical Analysis and ODEs · Mathematics 2020-05-11 Asha Ram Gairola , Karunesh Kumar Singh

We establish inverse and direct theorems on best approximations in quasi-normed Abelian groups through bilateral Bernstein-Jackson inequalities with exact constants. Using integral representations for quasi-norms of functions $f$ in…

Functional Analysis · Mathematics 2024-10-22 Oleh Lopushansky

We discuss the notion of optimal polynomial approximants in multivariable reproducing kernel Hilbert spaces. In particular, we analyze difficulties that arise in the multivariable case which are not present in one variable, for example, a…

Complex Variables · Mathematics 2022-05-03 Meredith Sargent , Alan Sola

We study the q-analogue of Euler-Maclaurin formula and by introducing a new q-operator we drive to this form. Moreover, approximation properties of q-Bernoulli polynomials is discussed. We estimate the suitable functions as a combination of…

Classical Analysis and ODEs · Mathematics 2017-11-06 Mohammad Momenzadeh , Ibrahim Yusuf Kakangi

We derive inversion formulas involving orthogonal polynomials which can be used to find coefficients of differential equations satisfied by certain generalizations of the classical orthogonal polynomials. As an example we consider special…

Classical Analysis and ODEs · Mathematics 2007-05-23 Roelof Koekoek

We present a theoretical analysis of the approximation properties of convolutional architectures when applied to the modeling of temporal sequences. Specifically, we prove an approximation rate estimate (Jackson-type result) and an inverse…

Machine Learning · Computer Science 2023-05-31 Haotian Jiang , Qianxiao Li

We give the theorem of coincidence of a class of functions defined by a generalised modulus of smoothness with a class of functions defined by the order of the best approximation by algebraic polynomials. We also prove the appropriate…

Functional Analysis · Mathematics 2012-08-28 Faton M. Berisha

In this paper we obtain several extensions to the quaternionic setting of some results concerning the approximation by polynomials of functions continuous on a compact set and holomorphic in its interior. The results include approximation…

Complex Variables · Mathematics 2023-07-19 Sorin G. Gal , Irene Sabadini

We introduce an asymmetric operator of generalised translation, define the generalised modulus of smoothness by its means, and obtain the direct and inverse theorems in approximation theory for it.

Functional Analysis · Mathematics 2012-08-31 Mikhail K. Potapov , Faton M. Berisha

We obtain strong converse inequalities for the Bernstein polynomials with explicit asymptotic constants. We give different estimation procedures in the central and non-central regions of [0,1]. The main ingredients in our approach are the…

Classical Analysis and ODEs · Mathematics 2024-09-06 José A. Adell , Daniel Cárdenas-Morales

We prove a strong simultaneous Diophantine approximation theorem for values of additive and multiplicative functions provided that the functions have certain regularity on the primes.

Number Theory · Mathematics 2009-06-18 Emre Alkan , Kevin Ford , Alexandru Zaharescu

We continue the study of the construction of analytical coefficients of the epsilon-expansion of hypergeometric functions and their connection with Feynman diagrams. In this paper, we show the following results: Theorem A: The multiple…

High Energy Physics - Theory · Physics 2009-11-18 M. Yu. Kalmykov , B. F. L. Ward , S. A. Yost

Complex signed measures of finite total variation are a powerful signal model in many applications. Restricting to the $d$-dimensional torus, finitely supported measures allow for exact recovery if the trigonometric moments up to some order…

Numerical Analysis · Mathematics 2022-03-23 Paul Catala , Mathias Hockmann , Stefan Kunis , Markus Wageringel

In this paper we introduce a new family of Bernstein-type exponential polynomials on the hypercube $[0, 1]^d$ and study their approximation properties. Such operators fix a multidimensional version of the exponential function and its…

Classical Analysis and ODEs · Mathematics 2024-05-28 Laura Angeloni , Danilo Costarelli , Chiara Darielli