On the weighted trigonometric Bojanov-Chebyshev extremal problem
Abstract
We investigate the weighted Bojanov-Chebyshev extremal problem for trigonometric polynomials, that is, the minimax problem of minimizing , where is a sufficiently nonvanishing, upper bounded, nonnegative weight function, the norm is the corresponding weighted maximum norm on the torus , and is a trigonometric polynomial with prescribed multiplicities of root factors . If the are natural numbers and their sum is even, then is indeed a trigonometric polynomial and the case when all the are 1 covers the Chebyshev extremal problem. Our result will be more general, allowing, in particular, so-called generalized trigonometric polynomials. To reach our goal, we invoke Fenton's sum of translates method. However, altering from the earlier described cases without weight or on the interval, here we find different situations, and can state less about the solutions.
Cite
@article{arxiv.2309.06083,
title = {On the weighted trigonometric Bojanov-Chebyshev extremal problem},
author = {Béla Nagy and Szilárd Gy. Révész},
journal= {arXiv preprint arXiv:2309.06083},
year = {2023}
}