x=[-1:0.01:1]; x1=[1:0.01:2]; 

y=cos(5*pi*x).*(cos(pi*x/2)).^2;

yy=[y x1*0];
xx=[x x1];

clf;
plot(xx,yy);

hold on;
plot(x,(cos(pi*x/2)).^2,'-.');
plot(x,-(cos(pi*x/2)).^2,'-.');


