Journal of Inequalities and Applications 
Volume 4 (1999), Issue 1, Pages 83-89
doi:10.1155/S1025583499000302

On the paths to the zeros of a polynomial

Bernard Beauzamy

Société de Calcul Mathématique, S. A. 111, Faubourg Saint Honoré, Paris 75008, France

Received 5 September 1998; Revised 7 October 1998

Abstract

Let P(z) be a polynomial in one complex variable, with complex coefficients, and let z1,,zn be its zeros. Assume, by normalization, that P(0)=1. The direct path from 0 to the root zj is the set {P(tzj),0t1}. We are interested in the altitude of this path, which is |P(tzj)| . We show that there is always a zero towards which the direct path declines near 0, which means |P(tzj)|<|P(0)| if t is small enough. However, starting with degree 5, there are polynomials for which no direct path constantly remains below the altitude 1.