clc; close all;

freqz([1 0 0 0 1],[1 0 0 0 -0.8145]);
n = 0:200;

x = sin(pi*n/2)+5*cos(pi*n);
y = filter([1 0 0 0 1],[1 0 0 0 -0.8145],x);

figure;
stem(n,x);
hold on
stem(n,y); 
hold off;
xlabel('n');
legend('x[n]','y[n]');