% Figure 2.9
a = [-1.5 1]; b = [0 0 2];
y0 = [2 1]; x0 = [0 0];
n = 0:20;
x = ones(1,length(n));
y = recur(a,b,n,x,x0,y0);
stem(n,y,'filled')
xlabel('n')
ylabel('y[n]')