symplectic map as our main integration method (wisdom & holman 1991; kinoshita， yoshida & nakai 1991) with a special start-up procedure to reduce the uncation error of angle variables，‘warm start’(saha & tremaine 1992， 1994).
the stepsize for the numerical integrations is 8 d throughout all integrations of the nine planets (n±1，2，3)， which is about 1/11 of the orbital period of the innermost planet (mercury). as for the determination of stepsize， we partly follow the previous numerical integration of all nine planets in sussman & wisdom (1988， 7.2 d) and saha & tremaine (1994， 225/32 d
对火星轨道变化问题的最后解释(14/49)