I am not sure what you mean by solving for diagonal blocks. The solver is general; it is the preconditioner that is block diagonal. If you want to use MPI, I assume that you have a large system. In this case, direct solvers are not very effective and you need to use an iterative solver. deal.II's iterative solvers work with any BlockSparseMatrix. The tutorials show you how to take advantage of the blocks to build a good preconditioner. If you don't want to use a preconditioner, that's fine. The code will be similar to what you have now but it will be slow.
Le mar. 23 août 2022 à 09:19, Masoud Ahmadi <[email protected]> a écrit : > Thanks for the reply. > I had seen that, they solve it for the "diagonal" blocks; I want a general > method. My system of equations is not like any special cases in the > Tutorials. > As I said, I solve the one without Trilinos/PETSc by: > > SparseDirectUMFPACK A_direct; > A_direct.initialize(K); > A_direct.vmult(Q_stp, R); > > I am looking for something similar. > > On Tuesday, 23 August 2022 at 13:57:18 UTC+1 [email protected] wrote: > >> They do. Take for example step-70, the matrix is a >> LA::MPI::BlockSparseMatrix >> <https://www.dealii.org/9.3.3/doxygen/deal.II/namespaceLinearAlgebraDealII.html#a34f060e2c5e047fdc12c76d047c7c098> >> which is a PETSc or a Trilinos BlockSpaceMatrix depending on how deal.II >> was configured. >> >> Bruno >> >> Le mar. 23 août 2022 à 06:43, Masoud Ahmadi <[email protected]> a >> écrit : >> >>> Dear Bruno, >>> >>> Thanks for your reply. >>> I had seen those before, but, unfortunately none of those solve a >>> general PETSc/Trilinos BlockSparseMatrix problem. >>> >>> >>> On Monday, 22 August 2022 at 15:51:03 UTC+1 [email protected] wrote: >>> >>>> Hi, >>>> >>>> If you search for "block solver" here >>>> https://dealii.org/developer/doxygen/deal.II/Tutorial.html, you will >>>> see all the tutorials that use block solvers. I think that only deal.II's >>>> own solvers support BlockSparseMatrix directly. >>>> >>>> Best, >>>> >>>> Bruno >>>> >>>> On Monday, August 22, 2022 at 9:02:28 AM UTC-4 [email protected] >>>> wrote: >>>> >>>>> Dear All, >>>>> >>>>> The following system of equations: >>>>> KQ=R >>>>> where, >>>>> [image: Screenshot from 2022-08-22 13-45-45.png] >>>>> were solved using BlockSparseMatrix to form tangent matrix K. It was >>>>> solved by: >>>>> >>>>> SparseDirectUMFPACK A_direct; >>>>> A_direct.initialize(K); >>>>> A_direct.vmult(Q_stp, R); >>>>> >>>>> Now, I'm trying to run my code with MPI using PETSc/Trilinos, but the >>>>> solver does not except PETSc/Trilinos BlockSparseMatrix. How do we solve >>>>> such a general system of equations? >>>>> >>>> -- >>> 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 a topic in the >>> Google Groups "deal.II User Group" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/dealii/vRkKqpMC21E/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/dealii/96e7565f-4e69-4bb9-8de8-ddcf4f3d4067n%40googlegroups.com >>> <https://groups.google.com/d/msgid/dealii/96e7565f-4e69-4bb9-8de8-ddcf4f3d4067n%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 a topic in the > Google Groups "deal.II User Group" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/dealii/vRkKqpMC21E/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/4cb3ddef-efc4-4921-8fe7-b9e969a64d98n%40googlegroups.com > <https://groups.google.com/d/msgid/dealii/4cb3ddef-efc4-4921-8fe7-b9e969a64d98n%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. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CAGVt9eOwrLzzGwRkvi-cFQy5YB9RRfXOfiGVcxVq0d0Lr7DF-w%40mail.gmail.com.
