passion方程的第一类边界条件的数值解，边界条件过于复杂而无法求得解析解。这就需要借助于数值法来求电磁场的数值解。有限差分法便是一种比较容易的数值解法。-Numerical Solution of the first boundary condition passion equations and boundary conditions are too complex to be obtained by analytical solution. This requires the help