Evolution of the orbital parameters for three different fits, stable for at least 10⁸ years. The best 2:1 MMR fit (left panels), the best stable fit from the low-eccentricity region (middle panels), and the fit with the most circular orbits (right panels). In the 2:1 MMR fit the gravitational perturbation between the planets is much larger than in the other two cases. It is easy to see that eccentricities for given epochs can be much larger than their values at the initial epoch of the integration. For convenience the evolution of the semi-major axes, eccentricities, the resonant angles (third row) and the Δω_b,c are given for 500 and 10⁵ years, respectively. The bottom row gives the orbital precession region, the sum of orbits for each integration output.