I developed finite element program (MFEM) in java for BVP &IVP to compute partial differential equation. I am facing one problem and description is as follows my problem is on generalized eigenvalue problem generated in wave propagation through rectangular wave guide in TE mode. (Differential equation is scalar Helmholtz equation). I am getting correct answer but without specifying Dirichlet boundary condition! (Tangential component of electric field should be zero on boundary element). and if i applied boundary condition, getting same answer but field plot is different . one thing i used nodal based rectangular element and mesh generated in my own flash program Mmesh. please help me to solve above problem.