[petsc-users] Using BDDC preconditioner for assembled matrices

[Jed Brown]

Did you assemble "Neumann" problems that are compatible with your
definition of interior/interface degrees of freedom?

Abdullah Ali Sivas <abdullahasivas at gmail.com> writes:

> Dear all,
>
> I have a series of linear systems coming from a PDE for which BDDC is an
> optimal preconditioner. These linear systems are assembled and I read them
> from a file, then convert into MATIS as required (as in
> https://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex72.c.html
> ). I expect each of the systems converge to the solution in almost same
> number of iterations but I don't observe it. I think it is because I do not
> provide enough information to the preconditioner. I can get a list of inner
> dofs and interface dofs. However, I do not know how to use them. Has anyone
> have any insights about it or done something similar?
>
> Best wishes,
> Abdullah Ali Sivas