The Python wrapper for PETSc may be missing some functionality; there is a manual process involved in creating new ones. You could poke around the petsc4py source and see how easy it would be to add more functionality that you need.
> On Sep 30, 2019, at 10:13 AM, Jan Grießer <[email protected]> wrote: > > I configured PETSc with MUMPS and tested it already for the spectrum slicing > method in Slepc4py but i have problems in setting up the LU factorization in > the PETSc4py. Since i do not find the corresponding methods and commands in > the source code. Thats why is was wondering if this is even possible in the > python version. > > Am Mo., 30. Sept. 2019 um 16:57 Uhr schrieb Smith, Barry F. > <[email protected]>: > > If you want a parallal LU (and hence the ability to build the inverse in > parallel) you need to configure PETSc with --download-mumps > --download-scalapack > > Barry > > > > On Sep 30, 2019, at 9:44 AM, Jan Grießer <[email protected]> > > wrote: > > > > Is the MatMumpsGetInverse also wrapped to the python version in PETSc4py ? > > If yes is there any example for using it ? > > My other question is related to the LU factoriation > > (https://www.mcs.anl.gov/petsc/documentation/faq.html#invertmatrix). > > Is the LU factorization only possible for sequential Aij matrices ? I read > > in the docs that this is the case for ordering. > > After setting up my matrix A, B and x i tried: > > r, c = dynamical_matrix_nn.getOrdering("nd") > > fac_dyn_matrix = dynamical_matrix_nn.factorLU(r,c) > > > > resulting in an error: > > [0] No support for this operation for this object type > > [0] Mat type mpiaij > > > > Am Fr., 27. Sept. 2019 um 16:26 Uhr schrieb Zhang, Hong > > <[email protected]>: > > See ~petsc/src/mat/examples/tests/ex214.c on how to compute selected > > entries of inv(A) using mumps. > > Hong > > > > On Fri, Sep 27, 2019 at 8:04 AM Smith, Barry F. via petsc-users > > <[email protected]> wrote: > > > > MatMumpsGetInverse() maybe useful. Also simply using MatMatSolve() with the > > first 1000 columns of the identity and "throwing away" the part you don't > > need may be most effective. > > > > Barry > > > > > > > > > On Sep 27, 2019, at 3:34 AM, Jan Grießer via petsc-users > > > <[email protected]> wrote: > > > > > > Hi all, > > > i am using petsc4py. I am dealing with rather large sparse matrices up to > > > 600kx600k and i am interested in calculating a part of the inverse of the > > > matrix(I know it will be a dense matrix). Due to the nature of my > > > problem, I am only interested in approximately the first 1000 rows and > > > 1000 columns (i.e. a large block in the upper left ofthe matrix). Before > > > I start to play around now, I wanted to ask if there is a clever way to > > > tackle this kind of problem in PETSc in principle. For any input I would > > > be very grateful! > > > Greetings Jan > > >
