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 $M\leq n$, 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.