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