function[x,n]=xlpy(x1,n1,n0) n=n1+n0;x=x1; xlabel('n') axis([min(n)-1,max(n)+1,min(x)-0.5,max(x)+0.5])x=[3,3,3,3,2,0,1]; n=-3:3; [x1,n1]=xlpy(x,n,4) [x2,n2]=xlpy(x,n,-2) n=min([n1,n2]):max([n1,n2]) N=max([n1,n2])-min([n1,n2]) y1=zeros(1,N) y2=zeros(1,N) y1(find(n>=min(n1)&n<max(n1)))=x1 y2(find(n>=min(n2)&n<max(n2)))=x2 y=y1.*y2 stem(n,y,'filled'); title('x(n-4)x(n+2)')请问一下大家这个程序哪里有问题呢显示是一张空白图表