We obtain a global version of the Hamiltonian KAM theorem for invariant Lagrangean tori by glueing together local KAM conjugacies with help of a partition of unity. In this way we find a global… (More)

In this article we thoroughly investigate the possibility of employing the exact computation of the free rigid body motion as a component of splitting methods for problems of rigid bodies subject to… (More)

We study the ellipticity and the “Nekhoroshev stability” (stability properties for finite, but very long, time scales) of the Riemann ellipsoids. We provide numerical evidence that the regions of… (More)

We revive the elementary idea of constructing symplectic integrators for Hamiltonian ows on manifolds by covering the manifold with the charts of an atlas, implementing the algorithm in each chart… (More)

Directional Quasi–Convexity (DQC) is a sufficient condition for Nekhoroshev stability, that is, stability for finite but very long times, of elliptic equilibria of Hamiltonian systems. The numerical… (More)

Energy is in general not conserved for mechanical nonholonomic systems with affine constraints. In this article we point out that, nevertheless, in certain cases, there is a modification of the… (More)

We return to the Keplerian or n-shell approximation to the hydrogen atom in the presence of weak static electric and magnetic fields. At the classical level, this is a Hamiltonian system with the… (More)

preprint numerics no. 6/2007 norwegian university of science and technology trondheim, norway We discuss techniques for the direct, exact computation of the solution of the equations of motion of a… (More)