Canonical forms for Hamiltonian and symplectic matrices and pencils

We study canonical forms for Hamiltonian and symplectic matrices or pencils under equivalence transformations which keep the class invariant. In contr ast to other canonical forms our forms are as close as possible to a triang ular structure in the same class. We give necessary and sufficient conditio ns for the existence of Hamiltonian and symplectic triangular Jordan, Krone cker and Schur forms. The presented results generalize results of Lin and H o (On Schur type decompositions for Hamiltonian and symplectic pencils, Tec hnical Report, Institute of Applied Mathematics, National Tsing Hua Univers ity, Taiwan, 1990) and simplify the proofs presented there. (C) 1999 Elsevi er Science Inc. All rights reserved. AMS classification: 15A21; 65F15; 93B4 0.