Are there some Matlab codes of FEM for discretizing the three-dimensional Helmholtz equation with first order Sommerfeld boundary conditions? Certainly, the FEniCS package (or other C++ -based codes) for Helmholtz equations have been available online. However, I am not very be good at the these codes? In addition, if I want to write myself the Matlab codes of FEM for Helmholtz equations, what needs to be considered ? Especially, how to deal with the boundary nodes, when I evaluate the entries of stiff matrices. If who are interested into this topic, please send email ([email protected]) to me. Recently, I have a interesting ideas about a physics simulations problem, in which the 3D Helmholtz (even Maxwell ) equations are need to discretized by FEM, or weak FEM, Hybrid Discontinuous Galerkin method.