Existence and numerical approximations of periodic solutions of semilinear fourth-order differential equations

A multiplicity result of existence of periodic solutions with prescribed wavelength for a class of fourth-order nonautonomous differential equations related either to the extended Fisher–Kolmogorov or to the Swift–Hohenberg equation is proved. Variational approach is used. Some numerical solutions are calculated via the finite element method.  2002 Elsevier Science (USA). All rights reserved