Generalized Hurwitz matrices, generalized Euclidean algorithm, and forbidden sectors of the complex plane

Abstract

Given a polynomial \[ f(x)=a_0x^n+a_1x^{n-1}+\cdots +a_n \] with positive coefficients $a_k$, and a positive integer $M\le n$, we define a(n infinite) generalized Hurwitz matrix $H_M(f):=(a_{Mj-i}{)}_{i,j}$. We prove that the polynomial $f(z)$ does not vanish in the sector $$\left\{z\in \mathbb{C}:|\arg (z)|<\frac{\pi }{M}\right\}$$ whenever the matrix $H_M$ is totally nonnegative. This result generalizes the classical Hurwitz' Theorem on stable polynomials ($M=2$), the Aissen-Edrei-Schoenberg-Whitney theorem on polynomials with negative real roots ($M=1$), and the Cowling-Thron theorem ($M=n$). In this connection, we also develop a generalization of the classical Euclidean algorithm, of independent interest per se.

26 pages, 1 figure

References in corpus (1)

• Polynomials, roots, and interlacing

Cited by in corpus (2)

• Total nonnegativity of finite Hurwitz matrices and root location of polynomials
• Hurwitz matrices of doubly infinite series