Proposal: Create a penrose-tiling tag, to be used in conjunction with tiling. Most questions with the tiling tag ask whether some tiling is possible, or ways of finding solutions to a particular problem, while questions about Penrose tilings are usually much less about problem-solving and instead...

I have the given problem to solve: Solve the eigenvalue problem for $-\Delta$ on the quarter-circle $x^2+y^2\leq R^2, x\geq 0,\ y\geq 0$ with homogeneous Dirichlet conditions. This is what I did. Since we have a Dirichlet homogeneous condition, we can prepare the Ansatz : $$u(r,\theta)=u(r)\si...