In Episode 207, "Convergence," an old college rival comes to CalSci (Marshall Penfield, played by Colin Hanks,) to present new research on a gap he has found in Charlie's proof. Although Charlie does find a way to resolve the error term, it isn't clear to many people watching still what type of math Charlie really does do! What he studies falls into the area of probability and statistics involving what are called "random matrices." While the first activity has no prerequisites, the latter activities all assume some basic knowledge of linear algebra, matrices, and determinants.