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
