This picture is supposed to be illustrating a phenomenon?!?! (ODE related)

[LivinLaVivaPollo]

I've been working on this oscillator problem on matlab, and arrived at this graph... It's supposed to represent a phenomenon of some sort, but I can't quite figure out what it is. It's amplitude is 2... it's not periodic... any math mavens out there willing to give me a hand?

sigh

 

[Anubis]

they look like wave packets. but thats physics