ex3
clear variables;

n = 0:100;
Fs = 10^3;
Fa = 100;
x = 2*cos(2*pi*Fa/Fs*n + pi/4);
x_bialternata = abs(x)
x_ma = (x+x_bialternata) / 2;

figure,
subplot(3,1,1); stem(n,x);
subplot(3,1,2); stem(n,x_bialternata);
subplot(3,1,3); stem(n,x_ma);