Arnold diffusion in symplectic lattice maps

In numerical experiments with Hamiltonian systems, round- off errors can be avoided by using symplectic lattice maps. This increases the accuracy of long-term studies of individual orbits. However, it is shown here that estimates of the mean local Arnold diffusion rate (in coupled standard maps) do not change when a lattice map is used. This is important because it reinforces the belief that statistical properties of ensembles of orbits are not significantly affected by roundoff error.