How to calculate the eigenvalues and eigenvectors of the normal flux matrix and the upwind flux for such a system？
The second problem is to compute the mass matrix over D^k as J * M. We can’t do this in general for quads
Why?
3) DG discretization of the Laplacian on for the periodic uniform mesh，How do we calculate the first D1 and last element D, using the BR1 formulation
