We use a recent result by Cabezas et al. [1] to build up an approximate solution to the gravitational field created by a rigidly rotating polytrope. We solve the linearized Einstein equations inside and outside the surface of zero pressure including second-order corrections due to rotational motion to get an asymptotically flat metric in a global harmonic coordinate system. We prove that if the...

Objectives . A finite-difference computational algorithm is proposed for solving a mixed boundary-value problem the Poisson equation given in two-dimensional irregular domains. Methods To solve problem, generalized curvilinear coordinates are used. The physical domain mapped to (unit square) space of coordinates. original written and approximated on uniform grid domain.The obtained results non-...

Phase fitting has been extensively used during the last years to improve the behaviour of numerical integrators on oscillatory problems. In this work, the benefits of the phase fitting technique are embedded in discrete Lagrangian integrators. The results show improved accuracy and total energy behaviour in Hamiltonian systems. Numerical tests on the long term integration (10 periods) of the 2-...