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
