I want to find the frequencies of vibration of a circular and square drum. To do this, I need to solve a 2-dimensional wave equation (PDE) with boundary conditions. Every method that I have researched to solve this uses separation of variables to generate two ODE's, and this is referred to as the "eigenvalue problem". My question is, is there any other way to do this that does not use separation of variables? I want to find approximate eigenvalues using a numerical method (like power method) but not sure if it is possible.
Any information would be appreciated