On Feb 25, 2013, at 6:47 PM, Jelena Slivka <slivkaje at gmail.com> wrote:
> Thank you very much, but I need to access this value in my program and not > just print it, is there a way to do this? You need to look at the code that prints out the determinant and call the same routine from your code directly. > Also, I need to use Cholesky factorization, is there a way to avoid MUMPS so > I could access the diagonal? If the problem is small enough to run sequentially then you can just the MPIBAIJ format Cholesky and access the diagonal directly. Barry > > > On Mon, Feb 25, 2013 at 7:13 PM, Barry Smith <bsmith at mcs.anl.gov> wrote: > > Jelena, > > MUMPS has its own (complicated) data structure for storing the factored > matrix, you cannot easily look inside it. > > However, fortunately MUMPS has a way of accessing the determinate of > the matrix directly. Look at src/mat/impls/aij/mpi/mumps.c and search for the > word determinant, you will find the command line argument to have it computed > and where it will be printed out if you call MatView() on the factored > matrix. You mush pass the PetscViewerFormat PETSC_VIEWER_ASCII_INFO to > PetscViewerSetFormat() before viewing the matrix. > > Good luck, > > Barry > > On Feb 25, 2013, at 6:02 PM, Jelena Slivka <slivkaje at gmail.com> wrote: > > > Hello, > > I am trying to find the determinant of the matrix. I have found this thread: > > > > http://lists.mcs.anl.gov/pipermail/petsc-users/2010-July/006716.html > > > > But, could you please explain how to access the data structure directly? > > So far I have tried the following: > > > > #include <petsc-private/matimpl.h> > > #include <../src/mat/impls/aij/seq/aij.h> > > ... > > // (Solving the system A*x = rhs > > MatSetOption(A, MAT_SPD, PETSC_TRUE); > > Mat F; > > MatGetFactor(A, MATSOLVERMUMPS, MAT_FACTOR_CHOLESKY, &F); > > MatFactorInfo factinfo; > > MatFactorInfoInitialize(&factinfo); > > IS perm, iscol; > > MatGetOrdering(A, MATORDERINGNATURAL, &perm, &iscol); > > MatCholeskyFactorSymbolic(F, A, perm, &factinfo); > > MatCholeskyFactorNumeric(F, A, &factinfo); > > ISDestroy(&iscol); > > ISDestroy(&perm); > > > > MatSolve(F, rhs, x); > > > > // Now I would like to access the diagonal part of the matrix F, can I do > > something like: > > > > Mat_SeqAIJ *aa = (Mat_SeqAIJ*)F->data; > > > > Do you maybe have an example I could look at? > > > > Grateful in advance, > > Jelena > >
