English

From asymptotic distribution and vague convergence to uniform convergence, with numerical applications

Numerical Analysis 2023-09-08 v1 Numerical Analysis Probability

Abstract

Let {Λn={λ1,n,,λdn,n}}n\{\Lambda_n=\{\lambda_{1,n},\ldots,\lambda_{d_n,n}\}\}_n be a sequence of finite multisets of real numbers such that dnd_n\to\infty as nn\to\infty, and let f:ΩRdRf:\Omega\subset\mathbb R^d\to\mathbb R be a Lebesgue measurable function defined on a domain Ω\Omega with 0<μd(Ω)<0<\mu_d(\Omega)<\infty, where μd\mu_d is the Lebesgue measure in Rd\mathbb R^d. We say that {Λn}n\{\Lambda_n\}_n has an asymptotic distribution described by ff, and we write {Λn}nf\{\Lambda_n\}_n\sim f, if limn1dni=1dnF(λi,n)=1μd(Ω)ΩF(f(x))dx() \lim_{n\to\infty}\frac1{d_n}\sum_{i=1}^{d_n}F(\lambda_{i,n})=\frac1{\mu_d(\Omega)}\int_\Omega F(f({\boldsymbol x})){\rm d}{\boldsymbol x}\qquad\qquad(*) for every continuous function FF with bounded support. If Λn\Lambda_n is the spectrum of a matrix AnA_n, we say that {An}n\{A_n\}_n has an asymptotic spectral distribution described by ff and we write {An}nλf\{A_n\}_n\sim_\lambda f. In the case where d=1d=1, Ω\Omega~is a bounded interval, Λnf(Ω)\Lambda_n\subseteq f(\Omega) for all nn, and ff satisfies suitable conditions, Bogoya, B\"ottcher, Grudsky, and Maximenko proved that the asymptotic distribution (*) implies the uniform convergence to 00 of the difference between the properly sorted vector [λ1,n,,λdn,n][\lambda_{1,n},\ldots,\lambda_{d_n,n}] and the vector of samples [f(x1,n),,f(xdn,n)][f(x_{1,n}),\ldots,f(x_{d_n,n})], i.e., limnmaxi=1,,dnf(xi,n)λτn(i),n=0,() \lim_{n\to\infty}\,\max_{i=1,\ldots,d_n}|f(x_{i,n})-\lambda_{\tau_n(i),n}|=0, \qquad\qquad(**) where x1,n,,xdn,nx_{1,n},\ldots,x_{d_n,n} is a uniform grid in Ω\Omega and τn\tau_n is the sorting permutation. We extend this result to the case where d1d\ge1 and Ω\Omega is a Peano--Jordan measurable set (i.e., a bounded set with μd(Ω)=0\mu_d(\partial\Omega)=0). See the rest of the abstract in the manuscript.

Keywords

Cite

@article{arxiv.2309.03662,
  title  = {From asymptotic distribution and vague convergence to uniform convergence, with numerical applications},
  author = {Giovanni Barbarino and Sven-Erik Ekström and Carlo Garoni and David Meadon and Stefano Serra-Capizzano and Paris Vassalos},
  journal= {arXiv preprint arXiv:2309.03662},
  year   = {2023}
}