x=-7:1e-2:7;
y=cos(-pi*x/10).^2;
z=y.*sin(5*x);
f=y.*cos(5*x);

plot(x,y,'k','linewidth',2)
hold on
plot(x,-y,'k--','linewidth',2)
plot(x,z,'r')
plot(x,f,'b')
hold off
