% Example 2.11%% x(n) = u(n)-u(n-10)% h(n) = (0.9)^n * u(n)% diff eqn: y(n) - 0.9y(n-1) = x(n)%b = [1]; a = [1,-0.9];n = -5:50; x = stepseq(0,-5,50) - stepseq(10,-5,50);y = filter(b,a,x);subplot(1,1,1);subplot(2,1,2); stem(n,y); title('Output sequence')xlabel('n'); ylabel('y(n)'); axis([-5,50,-0.5,8])