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arXiv · 2607.23375

What is Jackson's constant?

Rikhav Shah·John Urschel·Nicholas West
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Abstract

We prove a refinement of Jackson's theorem on the approximation of Lipschitz functions by trigonometric polynomials. Our result precisely characterizes the leading error term associated with Jackson's construction. We do the same for a related construction commonly used in the kernel polynomial method for spectral density estimation, which is slightly better than Jackson's construction in this respect.

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Rikhav Shah, John Urschel, Nicholas West. 2026-07-25. What is Jackson's constant?. https://arxiv.org/abs/2607.23375

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