Addendum to "On the stability properties of polynomials with perturbed coefficients"

This note serves to point out that the method presented by Soh et aL [1] can be used to obtain the largest hypersphere which contains the coefficients of polynomials which have zeros only on or within any simply connected region
D
in the complex plane which is symmetric with respect to the real-axis. It is then extended to obtain the largest right circular hypercone which contains the coefficients of polynomials which have zeros only on or within any simply connected region
D
.