说明：  1.连续时间信号和离散时间信号的MATLAB 描述。 2.掌握连续信号和离散信号描述方法上的异同。 3.掌握信号的运算与变换。
(1 continuous time and discrete-time signals MATLAB signal description. 2 master similarities and differences between continuous signals and discrete signals described methods. 3 master computing and transform the signal.)