% Add text to a graphic 
k = linspace(-4,4,100);

omega = sqrt(1+k.^2);

hold on
plot(k,omega,'b');
plot(k,k,'r');
plot(k,-omega,'b');
plot(k,-k,'r');

plot(0,1,'b.')
h1=text(0,1,'inertia-waves');
set(h1,'HorizontalAlignment','center','color',[0 0 1])

h2=text(2.4,2.4,'gravity-waves');
set(h2,'color',[1 0 0])

hold off
