RUS  ENG
Full version
JOURNALS // Izvestiya Vysshikh Uchebnykh Zavedenii. Matematika // Archive

Izv. Vyssh. Uchebn. Zaved. Mat., 2022 Number 3, Pages 44–60 (Mi ivm9759)

This article is cited in 6 papers

Conjugate rational Foutier–Chebyshev operator and its approximation properties

P. G. Potseiko, Ye. A. Rovba

Yanka Kupala State University of Grodno, 22 Ozheshko str., Grodno, 230023 Republic of Belarus

Abstract: In this paper, a conjugate rational integral Fourier–Chebyshev operator associated with the system of Chebyshev–Markov algebraic fractions is constructed. Pointwise estimates of approximations on the segment $[-1,~1]$ of the conjugate function with density $(1-x)^{\gamma}, \gamma>1/2,$ and uniform estimates of approximations expressed in terms of a certain majorant are obtained. Asymptotic expression for majorants of approximations and optimal values of parameters that provide the highest speed decreasing majorants are found. At the corollary the corresponding estimates of approximations on the segment $[-1,~1]$ of the conjugate function under study by partial sums of conjugate polynomial Fourier–Chebyshev series are given.

Keywords: conjugate function, integral operator, rational approximation, pointwise estimate, asymptotic estimate, best approximation.

UDC: 517.5

Received: 24.06.2021
Revised: 20.07.2021
Accepted: 29.09.2021

DOI: 10.26907/0021-3446-2022-3-44-60


 English version:
Russian Mathematics (Izvestiya VUZ. Matematika), 2022, 66:3, 35–49


© Steklov Math. Inst. of RAS, 2024