Statistics of entries of matrices from the general linear group over a finite field

Abstract

Let ${\mathrm{GL}}_n({\mathbb{F}}_q)$ be the group of $n\times n$ invertible matrices over a finite field ${\mathbb{F}}_q$. How many matrices in ${\mathrm{GL}}_n({\mathbb{F}}_q)$ are there with a subset of their entries prescribed? Motivated by the random matrix theory of classical compact groups, we address this question and various variants, with a focus on asymptotic results that are valid as $n$ tends to infinity. Our methods are Fourier-analytic, with the main input being an exponential sum over ${\mathrm{GL}}_n({\mathbb{F}}_q)$, evaluated in 1955 by Hodges via elementary methods. Our results turn out to be related to investigations carried out in other fields, including coding theory, universality for $p$-adic matrices and algebraic combinatorics.

arXiv comment23 pages. Proposition 1.10 from v1 removed, will appear elsewhere