t=0:0.01:2*pi;
x=sin(3.0*pi*t);
x1=sin(3.3*pi*t);
x2=sin(3.5*pi*t);
axis([min(t) max(t) -2 2])
subplot(511);plot(t,x)
subplot(512);plot(t,x1)
subplot(513);plot(t,x1+x2)
subplot(514);plot(t,x2)
subplot(515);plot(t,x1-x2)