Author:
Bergweiler Walter,Eremenko Alexandre,Rempe Lasse
Abstract
AbstractLet A be a transcendental entire function of finite order. We show that, if the differential equation w″ + Aw = 0 has two linearly independent solutions with only real zeros, then the order of A must be an odd integer or one half of an odd integer. Moreover, A has completely regular growth in the sense of Levin and Pfluger. These results follow from a more general geometric theorem, which classifies symmetric local homeomorphisms from the plane to the sphere for which all zeros and poles lie on the real axis, and which have only finitely many singularities over finite non-zero values.
Publisher
Springer Science and Business Media LLC
Subject
General Mathematics,Analysis
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