自行设计产生两个离散序列信号，对其进行相加、乘及卷积运算。 利用filter命令求下面LTI系统的冲激响应，画出系统的零极点图，判断系统的稳定性、因果性。 绘出系统的频响曲线 -To design of two discrete sequence of signals , their sum , multiplication and convolution . Seeking the following LTI system impulse response filter com