可逆系统

sunyuanxin

书上的题
show that invertibility for a discrete-time linear system is equivalent to the following statement
the only input that produces y[n]=0 for all n is x[n]=0 for all n.
the analogous statement is also true for continuous-time linear system.
我就有点奇怪，如果一个系统是y[n]=x[n]+3,这也是一个线性可逆的系统，但是y[n]=0 for all n的对应输入时x[n]=-3 for all n,这就不成立了嘛。