From: Dong Xu <dxu@my...>  20070331 07:26:36

Hi, I have a simple 2D equation with the following form: Uxx+Uyy+Uxy=3D0 Uxx, Uyy are the 2nd partial derivative and Uxy is the mixed 2nd artial der= ivative. Since I'm not a math major, I'm having trouble setting up the weak formulat= ion due to the mixed derivative term. Thus I don't know how to implement = it with libMesh. Any help will be greatly appreciated. DX 