%lab2 
%#1c
b=[1.2,2.4,1.2];
a=[1,0,0.9];
n=[0:60]';
x=ones(size(n));
y=filter(b,a,x);
subplot(2,1,1)
stem(n,x)
grid on
xlabel('n')
ylabel('Amplitude')
title('input signal,x')
subplot(2,1,2)
stem(n,y,'r')
grid on
xlabel('n')
ylabel('Amplitude')
title('Output signal, y')
