Ordinary Differential Equations: Introduction and Qualitative Theory

Exploring the qualitative aspects of periodic solutions of ODEs, this edition extends the treatment of two-dimensional systems as well as periodic solutions in small parameter problems. It illustrates existence theorems with various examples, provides a detailed account of the Bendixson theory of solutions of two-dimensional autonomous systems, and presents a unified treatment of the perturbation problem for periodic solutions. The text also shows how topological degree is used to obtain significant extensions of perturbation theory and describes how the averaging method is used to study periodic solutions. It contains numerous exercises.