[Libmesh-users] About JFNK method! From: luyi - 2008-08-06 07:42:29 ```Hello, Derek, Roy told me that you are using JFNK now and keep the sparse matrix to fill with an inexact Jacobian for preconditioning, I am interesting about this too, so I want to know how to implement JFNK with nonlinearImplicitSystem? Just running with the line command "_ksp_matrix_free" or "_ksp_mf_operator"? I also want to use a matrix_free preconditioner and I need to store all diagonal dense matrix of each elem for speed up the user-provided "Kx=y" process, can you give me some suggestions? Do I need to write a matrix_free system inherited from ExplicitSystem or NonlinearImplicitSystem? Or just modify the solve() of petsc_nonlinear_solver.C? For my discontinuous galerkin code, because the elem_based FE family, I need to compute the sparse pattern with command "--implicit_neighbor_dofs", if I just need the diagonal dense matrix, how to implement? Just without this command? Best regards! Luyi -- Gas Turbine Research Center email: luyi06@... ```
 [Libmesh-users] About JFNK method! From: luyi - 2008-08-06 07:42:29 ```Hello, Derek, Roy told me that you are using JFNK now and keep the sparse matrix to fill with an inexact Jacobian for preconditioning, I am interesting about this too, so I want to know how to implement JFNK with nonlinearImplicitSystem? Just running with the line command "_ksp_matrix_free" or "_ksp_mf_operator"? I also want to use a matrix_free preconditioner and I need to store all diagonal dense matrix of each elem for speed up the user-provided "Kx=y" process, can you give me some suggestions? Do I need to write a matrix_free system inherited from ExplicitSystem or NonlinearImplicitSystem? Or just modify the solve() of petsc_nonlinear_solver.C? For my discontinuous galerkin code, because the elem_based FE family, I need to compute the sparse pattern with command "--implicit_neighbor_dofs", if I just need the diagonal dense matrix, how to implement? Just without this command? Best regards! Luyi -- Gas Turbine Research Center email: luyi06@... ```