  We derived a condition under which a coupled system consisting of two
finite-dimensional Hamiltonian systems becomes a Hamiltonian system. In many
cases, an industrial system can be modeled as a coupled system of some
subsystems. Although it is known that symplectic integrators are suitable for
discretizing Hamiltonian systems,the composition of Hamiltonian systems may not
be Hamiltonian. In this paper, focusing on a property of Hamiltonian systems,
that is, the conservation of the symplectic form, we provide a condition under
which two Hamiltonian systems coupled with interactions compose a Hamiltonian
system.
