Versal deformations and normal forms for reversible and Hamiltonian linear systems

The problem of this article is the characterization of equivalence classes and their versal deformations for reversible and reversible Hamiltonian matrices. in both cases the admissible transformations form a subgroup G of Gl(m). Therefore the Gl(m)-orbits of a given matrix may split into several G-orbits. These orbits are characterized by signs. For each sign we have a normal form and a corresponding versal deformation. The main tool in the characterization is reduction to the semi Simple case. (C) 1996 Academic Press, Inc.