Consider Birkhoff sums where is a billiard with a flat cusp
and stability index , and is an observable given by
. Here is the post-collisional angle between particle's velocity and
the normal to the boundary.
We choose a random initial condition
and plot the process , , given by
We send and animate the graph.
We also plot in light grey the graphs of with a few different values of .
Refresh the page to restart with a new initial contition.