English

Average Nikolskii factors for random trigonometric polynomials

Classical Analysis and ODEs 2025-03-24 v1

Abstract

For 1p,q1\le p,q\le \infty, the Nikolskii factor for a trigonometric polynomial TaT_{\bf a} is defined by Np,q(Ta)=TaqTap,  Ta(x)=a1+k=1n(a2k2coskx+a2k+12sinkx).\mathcal N_{p,q}(T_{\bf a})=\frac{\|T_{\bf a}\|_{q}}{\|T_{\bf a}\|_{p}},\ \ T_{\bf a}(x)=a_{1}+\sum\limits^{n}_{k=1}(a_{2k}\sqrt{2}\cos kx+a_{2k+1}\sqrt{2}\sin kx). We study this average Nikolskii factor for random trigonometric polynomials with independent N(0,σ2)N(0,\sigma^{2}) coefficients and obtain that the exact order. For 1p<q<1\leq p<q<\infty, the average Nikolskii factor is order degree to the 0, as compared to the degree 1/p1/q1/p-1/q worst case bound. We also give the generalization to random multivariate trigonometric polynomials.

Keywords

Cite

@article{arxiv.2503.16786,
  title  = {Average Nikolskii factors for random trigonometric polynomials},
  author = {Yun Ling and Jiaxin Geng and Jiansong Li and Heping Wang},
  journal= {arXiv preprint arXiv:2503.16786},
  year   = {2025}
}

Comments

17 pages

R2 v1 2026-06-28T22:29:10.768Z