Limit cycles

Limit cycles, or isolated periodic solutions, are the most common form of solution observed when modeling physical systems in the plane. Early investigations were concerned with mechanical and electronic systems, but periodic behavior is evident in all branches of science. Two limit cycles were plotted in Chap. 10 when considering the modeling of interacting species. The chapter begins with a historical introduction, and then the theory of planar limit cycles is introduced. Textbooks providing a more general introduction to the theory of limit cycles include [16, 17].