If you're using PETSc as your underlying solver, try the options
`-pc_factor_shift_type NONZERO -pc_factor_shift_amount 1e-15`
On Thu, Aug 23, 2018 at 2:58 PM, Renato Poli <rebp...@gmail.com> wrote:
> Hi
>
> I am getting trouble here again ... really need some help.
>
> I have part of the domain without flow (and thus without the pressure
> variable defined).
> As I could not export that (could not get write_discontinuous_exodusII to
> work) I just left the matrix empty, without major impact so far.
> However, now I am using LU preconditioning, which does not accept empty
> entries in the diagonal.
>
> How can I get through?
> Any suggestion?
>
> Thanks upfront.
> Renato
>
>
>
>
>
> On Thu, Aug 16, 2018 at 6:47 PM Renato Poli <rebp...@gmail.com> wrote:
>
> > Hi
> >
> > I see the stack trace below when writing a discontinuous timestep
> > (exo.write_discontinuous_timestep).
> > It happens when my variable is set only in part of the domain.
> > No problem arises if I use, instead: exo.write_equation_systems(fname,
> es)
> >
> > Any hint/workaround/idea?
> >
> > Thanks,
> > Renato
> >
> > This is how the variable is set.
> > | std::set<subdomain_id_type> active_subdomains;
> > | active_subdomains.clear();
> > | active_subdomains.insert(SUBDOMAIN_A);
> > | press_sys.add_variable ("p", SECOND, LAGRANGE, & active_subdomains);
> >
> > 0: libMesh::print_trace(std::ostream&)
> > 1: libMesh::MacroFunctions::report_error(char const*, int, char const*,
> > char const*)
> > 2:
> > libMesh::EquationSystems::build_discontinuous_solution_
> vector(std::__debug::vector<double,
> > std::allocator<double> >&,
> > std::__debug::set<std::__cxx11::basic_string<char,
> std::char_traits<char>,
> > std::allocator<char> >, std::less<std::__cxx11::basic_string<char,
> > std::char_traits<char>, std::allocator<char> > >,
> > std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>,
> > std::allocator<char> > > > const*) const
> > 3:
> > libMesh::ExodusII_IO::write_discontinuous_exodusII(std::__
> cxx11::basic_string<char,
> > std::char_traits<char>, std::allocator<char> > const&,
> > libMesh::EquationSystems const&,
> > std::__debug::set<std::__cxx11::basic_string<char,
> std::char_traits<char>,
> > std::allocator<char> >, std::less<std::__cxx11::basic_string<char,
> > std::char_traits<char>, std::allocator<char> > >,
> > std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>,
> > std::allocator<char> > > > const*)
> > 4:
> > libMesh::ExodusII_IO::write_timestep_discontinuous(std::__
> cxx11::basic_string<char,
> > std::char_traits<char>, std::allocator<char> > const&,
> > libMesh::EquationSystems const&, int, double,
> > std::__debug::set<std::__cxx11::basic_string<char,
> std::char_traits<char>,
> > std::allocator<char> >, std::less<std::__cxx11::basic_string<char,
> > std::char_traits<char>, std::allocator<char> > >,
> > std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>,
> > std::allocator<char> > > > const*)
> >
> >
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