说明：  常微分方程初值问题的数值解法 本程序主要采用经典四阶的R-K方法和四阶Adams预测-校正方法来求解常微分方程的数值解。
(Numerical Solution of Ordinary Differential Problems of this procedure using the classical fourth-order RK method and fourth-order Adams prediction- correction method to solve the numerical solution of ordinary differential equations.)