In this paper we present a complete perturbation
analysis for the Hamiltonian Schur form of a Hamiltonian
matrix under similarity transformations widht unitary
symplectic matrices. Both local linear and non-linear
, non-linear perturbation bounds are presented. The same
analysis is also carried out for a less condensed,
block-triangular form, and it is shown that this form is less sensitive to perturbations.
The analysis is based on the technique of splitting operators and
on a representation of the symplectic unitary group which is convenient
for perturbation analysis of condensed forms. Given
a perturbation in the initial Hamilttonian matrix, the perturbation in the Hamiltonian
Schur form and the unitary symplectic basis is constructed in the form
of power series expansions. As a corollary a perturbation
bound for the stable invariant subspace is obtained.