Hi again Feilpe, Regarding the lack of documentation, I’ve opened an issue on Github to track this. You can find that here: https://github.com/dealii/dealii/issues/12466 <https://github.com/dealii/dealii/issues/12466>
Best, Jean-Paul > On 15. Jun 2021, at 12:57, Jean-Paul Pelteret <jppelte...@gmail.com> wrote: > > Hi Feilpe, > > Firstly, I agree that the documentation is very light on details on how to > use the linear operators with Trilinos linear algebra types. We can > definitely improve this, and any contributions to that effect would be > greatly appreciated! > > Right now, I can direct you to a few of the tests that use Trilinos LA in > conjunction with the inverse operator, so that you can compare what you have > and figure out what the problematic differences are. There is this one, for > instance > https://github.com/dealii/dealii/blob/master/tests/lac/linear_operator_12a.cc#L323-L341 > > <https://github.com/dealii/dealii/blob/master/tests/lac/linear_operator_12a.cc#L323-L341> > that looks like a similar setup to yours, and > https://github.com/dealii/dealii/blob/master/tests/lac/schur_complement_04.cc#L126-L137 > > <https://github.com/dealii/dealii/blob/master/tests/lac/schur_complement_04.cc#L126-L137> > that uses a Trilinos::SolverCG (as opposed to deal.II’s solver). > > Comparing to both of these, I think that the important point might be that > the preconditioner must be declared (out-of-line) before the > inverse_operation() function is called. The linear operators typically expect > the lifetime of the LA objects to exceed that of the operators, and so you > have to first create the matrix or preconditioner and then pass it to the > linear operators. This is similar to what you’d done when setting up op_M, > for example. The case of passing in a deal::PreconditionerIdentity() for > serial operations is a special case, and I don’t think that we’ve duplicated > that for TrilinosWrappers:: PreconditionerIdentity(). Maybe that could be > improved too. > > I hope that with this single change you’d be able to get your program > running. If not, then please do let us know so that we can try to help > further. > > Best, > Jean-Paul > > >> On 14. Jun 2021, at 19:18, Juan Felipe Giraldo <jfgiral...@gmail.com >> <mailto:jfgiral...@gmail.com>> wrote: >> >> Hello everyone, >> >> I have implemented a residual-minimization framework that somehow is similar >> to DPG. I want to extend my results by using parallelization using MPI with >> PETSc or Trilinos. >> So far, I have solved the saddle point problem using the Schur complement >> exactly how it is described in step 20. Now, I am trying to replicate >> exactly the same solver but using the MPI wrappers and the linear operators. >> >> The problem is that when I am trying to implement the inverse_operator to >> compute the Preconditioner of the Schur complement, I get an error saying >> that the functions are not matching "inverse_operator(op_aS, solver_aS, >> TrilinosWrappers::PreconditionIdentity())." >> >> There is no much documentation about linear operators in parallel solvers, >> so if anyone has any suggestion on how to fix this problem, it would be well >> appreciated. >> >> I have pasted the complete function in below: >> >> >> template <int dim> >> void FEMwDG<dim>:: >> solve() >> { >> TimerOutput::Scope t(computing_timer, "solve"); >> >> LA::MPI::PreconditionJacobi prec_M; >> LA::MPI::PreconditionJacobi::AdditionalData data; >> prec_M.initialize(system_matrix.block(0, 0), data); >> } >> >> auto &E = solution.block(0); >> auto &U = solution.block(1); >> const auto &L = system_rhs.block(0); >> const auto M = linear_operator<LA::MPI::Vector>(system_matrix.block(0, >> 0)); >> >> const auto op_M = linear_operator(M, prec_M); >> const auto op_B = >> linear_operator<LA::MPI::Vector>(system_matrix.block(0, 1)); >> const auto op_BT = >> linear_operator<LA::MPI::Vector>(system_matrix.block(1, 0)); >> >> ReductionControl inner_solver_control2(5000, >> 1e-18 * >> system_rhs.l2_norm(), >> 1.e-2); >> >> SolverCG<LA::MPI::Vector> cg(inner_solver_control2); >> const auto op_M_inv = inverse_operator(M, cg, prec_M); >> >> const auto op_S = op_BT * op_M_inv * op_B; >> const auto op_aS = op_BT * linear_operator<LA::MPI::Vector>(prec_M) * >> op_B; >> >> IterationNumberControl iteration_number_control_aS(30, 1.e-18); >> SolverCG<LA::MPI::Vector> solver_aS(iteration_number_control_aS); >> >> const auto preconditioner_S = >> inverse_operator(op_aS, solver_aS, >> TrilinosWrappers::PreconditionIdentity()); >> const auto schur_rhs = op_BT * op_M_inv * L ; >> >> SolverControl solver_control_S(2000, 1.e-12); >> SolverCG<LA::MPI::Vector> solver_S(solver_control_S); >> >> const auto op_S_inv = inverse_operator(op_S, solver_S, preconditioner_S >> ); >> >> U = op_S_inv * schur_rhs; >> std::cout << solver_control_S.last_step() >> << " CG Schur complement iterations to obtain convergence." >> << std::endl; >> E = op_M_inv * (L - op_B * U); >> } >> >> Thank you so much, >> >> Regards, >> Felipe >> >> >> >> >> >> -- >> The deal.II project is located at http://www.dealii.org/ >> <http://www.dealii.org/> >> For mailing list/forum options, see >> https://groups.google.com/d/forum/dealii?hl=en >> <https://groups.google.com/d/forum/dealii?hl=en> >> --- >> You received this message because you are subscribed to the Google Groups >> "deal.II User Group" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to dealii+unsubscr...@googlegroups.com >> <mailto:dealii+unsubscr...@googlegroups.com>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/dealii/40b8db07-5243-4603-825b-9e7850580206n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/dealii/40b8db07-5243-4603-825b-9e7850580206n%40googlegroups.com?utm_medium=email&utm_source=footer>. > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. 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