Dear Christophe, How can we implement Dirichelete boundary condition for wave equation in GetDP? In this case, the boundary condition is time dependent. Can we still put it as a constraint? Thanks a lot. Lin Ji Dept. of Math., Amos Eaton Rensselaer Polytechnic Institute 110 8th Street Troy, New York 12180-3590 Phone: 518-276,8377 (work)