x=1:20;
y1=x;
y2=sin(x/3);
y3=x.^2;

subplot(3,1,1)
plot(x, y1)
xlabel('x'), ylabel('y1'), title('x vs y1')

subplot(3,1,2)
plot(x, y2)
xlabel('x'), ylabel('y2'), title('x vs y2')

subplot(3,1,3)
plot(x, y3)
xlabel('x'), ylabel('y3'), title('x vs y3')