Salut,

Voila un exemple:

x=randint(1,5);
y=rectpulse(x,50);
s=sin(2*pi*(0:249)/25);
subplot(311);stem(upsample(x,50));axis([0 250 0 1.5]);grid
subplot(312);plot(y);axis([0 250 0 1.5]);grid...