说明：  判断微分方程是否为病态方程，分别用定步长、变步长和适合病态系统的数值积分方法对系统求解，并与解析解进行对比，分析每种方法的求解精度和速度。
(To determine whether the pathological differential equations, were used to set step, variable step size and suitable for pathological system numerical method for solving the system, and compared with the analytic solution, analysis of each method to solve the accuracy and speed.)