The asymptotic zero-counting measure of iterated derivaties of a class of meromorphic functions

Abstract

We give an explicit formula for the logarithmic potential of the asymptotic zero-counting measure of the sequence ${\lbrace (d^n/dz^n) (R(z) \mathrm{exp}T(z))\rbrace}^{\infty}_{n=1}$. Here, $R(z)$ is a rational function with at least two poles, all of which are distinct, and $T(z)$ is a polynomial. This is an extension of a recent measure-theoretic refinement of Pólya’s Shire theorem for rational functions.