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On the Constant and Step in Jackson's Inequality for Best Approximations by Trigonometric Polynomials and by Haar Polynomials
P. A. Andrianov, O. L. Vinogradov Saint Petersburg State University
Abstract:
Two sharp results for best approximations of periodic functions are established in this paper. We prove the sharpness of the step of the modulus of continuity in Jackson's inequality with least possible constant for approximations by trigonometric polynomials. We also prove the sharpness of the constants in a Jackson-type inequality for approximations by Haar polynomials in several variables.
Keywords:
sharp constant, Jackson's inequality, Haar system.
Received: 09.11.2015 Revised: 30.01.2016
Citation:
P. A. Andrianov, O. L. Vinogradov, “On the Constant and Step in Jackson's Inequality for Best Approximations by Trigonometric Polynomials and by Haar Polynomials”, Mat. Zametki, 100:3 (2016), 323–330; Math. Notes, 100:3 (2016), 345–351
Linking options:
https://www.mathnet.ru/eng/mzm11014https://doi.org/10.4213/mzm11014 https://www.mathnet.ru/eng/mzm/v100/i3/p323
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