用于描绘与计算不同角度入射进光纤的光在传输过程中的变化过程，通过修改参数数值得到不同长度下均衡模分布与稳态模分布-Used to portray different angles and calculation of income into the optical fiber during transmission of the change process, by modifying the parameter values to be of different lengths under the balanced-mode distribution and steady-state mode distribution