Periodic Solution of High-Order FDE with General Delays

In this paper the periodic solution problem of high-order Functional Differential Equations (FDE) with "general" delays is studied. By changing the original equations into its equivalent FDEs and using the characteristic equation of the equivalent FDEs, the sufficient and necessary condition on which the periodic solutions of the original equations exist is presented, i.e., characteristic equation of the equivalent FDEs has nonzero imaginary solutions.