Just one more dimension

Two weeks ago I decided to set of a full week for a little article. I had everything all worked out in my notes from way back, and all I needed to do was to add one more dimension to a numerical simulation that was working fine in 2D. It’s now two weeks later – but at least I get to stare angrily at plots like this one showing the joint probability density of the velocity of two independent harmonic oscillators. All I have to do is find the marginal distribution along one of the axes…