说明：  系统辨识课程实验所写的程序。使用递推最小二乘估计辨识系统参数。输出系统参数辨识结果以及辨识精度。程序可以直接运行。
(I wrote this program in my system identification course experiment. Using the recursive least squares estimation identification of system parameters. Output system parameter identification result and precision. The program can be run directly. )