From: LengWei <lengweee@gm...>  20081224 08:38:10

Hi, I'm trying to implement the pressure convectiondiffusion preconditioner for steadystate Navierstokes equaions. I am not sure if I am doing it in an approperate way... Here is the outline: In general, use the pestc precondition shell matrix, specificly, * build subblock Matrix manually * extract subvector form vector, namely (u,v,w) and p from x, using variable_first_local_dof * create some solver to perform the inverse operation of matrix, or mat vec multiplication Is there a more decent way to do this? BTW, there is a bug in dof_map.C, which I check out from svn, around line 915, >> if (var == n_vars1) _var_first_local_df.push_back(next_free_dof); _var_first_local_df[nvar+1] record the offset of vars, like [u_begin, v_begin, w_begin, p_begin, p_end], but without "if (var == n_vars1)", it becomes [u_begin, u_end, v_begin, v_end, w_begin, w_end, p_begin, p_end] Regards, Lengwei 