Abstract
We prove an analog of the Jackson inequality for a coconvex approximation of continuous periodic functions with the second modulus of continuity and a constant that depends on the location of the points at which a function changes its convexity.
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Popov, P.A. An Analog of the Jackson Inequality for Coconvex Approximation of Periodic Functions. Ukrainian Mathematical Journal 53, 1093–1105 (2001). https://doi.org/10.1023/A:1013325131321
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DOI: https://doi.org/10.1023/A:1013325131321