From: Shengli Xu <shengli.xu@gm...>  20060114 07:07:19

In Example 11: // Reposition the submatrices... The idea is this: // //     //  Kuu Kuv Kup   Fu  // Ke =3D  Kvu Kvv Kvp ; Fe =3D  Fv  //  Kpu Kpv Kpp   Fv  //     // // The \p DenseSubMatrix.repostition () member takes the // (row_offset, column_offset, row_size, column_size). // // Similarly, the \p DenseSubVector.reposition () member // takes the (row_offset, row_size) Kuu.reposition (u_var*n_u_dofs, u_var*n_u_dofs, n_u_dofs, n_u_dofs); Kuv.reposition (u_var*n_u_dofs, v_var*n_u_dofs, n_u_dofs, n_v_dofs); Kup.reposition (u_var*n_u_dofs, p_var*n_u_dofs, n_u_dofs, n_p_dofs); Kvu.reposition (v_var*n_v_dofs, u_var*n_v_dofs, n_v_dofs, n_u_dofs); Kvv.reposition (v_var*n_v_dofs, v_var*n_v_dofs, n_v_dofs, n_v_dofs); Kvp.reposition (v_var*n_v_dofs, p_var*n_v_dofs, n_v_dofs, n_p_dofs); Kpu.reposition (p_var*n_u_dofs, u_var*n_u_dofs, n_p_dofs, n_u_dofs); Kpv.reposition (p_var*n_u_dofs, v_var*n_u_dofs, n_p_dofs, n_v_dofs); Kpp.reposition (p_var*n_u_dofs, p_var*n_u_dofs, n_p_dofs, n_p_dofs); Fu.reposition (u_var*n_u_dofs, n_u_dofs); Fv.reposition (v_var*n_u_dofs, n_v_dofs); Fp.reposition (p_var*n_u_dofs, n_p_dofs); I don't understand these code. What are the structures of Total Dof Vector and Element Dof Vector? For example in 2D, the freedom of node is u , v. The total Dof Vector is like [u_1,u_2,...u_N, v_1, v_2,..., v_N], or like [u_1, v_1, u_2, v_2, ..., u_N, v_N], ( N is the node number). Suggestions: The examples are very usefully to help you understand libMesh. It was more better that the govering equation, the discrete finite element formulation are given. ShengliXu 