[petsc-users] How to get diagonal entries ...

[Hong Zhang]

Clemens:
>
> I did a Cholesky-decomposition using MUMPS and now I want to get the
> diagonal entries of the Cholesky-decomposition but MatGetDiagonal doesnt't
> seem to work.

MUMPS uses its internal data structure for matrix factorization and does not
provides user interface to access it, thus
Petsc has noway to do is as well.

Try option '-mat_mumps_icntl_4 4' (level of printing) to see if you can get
useful info from mumps. Other wise, send request to mumps developer.

Hong

>
> Thanks for your help - Clemens Domanig
>
> ...
> ierr=PCSetType( prec, PCCHOLESKY); CHKERRQ( ierr);
> ...
> ierr=PCFactorGetMatrix( prec, &M); CHKERRQ( ierr);
> ierr=MatGetDiagonal( M, z); CHKERRQ( ierr);
> printf("\nPivots:\n\n");
> ierr=VecView( z, PETSC_VIEWER_STDOUT_SELF); CHKERRQ( ierr);
>
> output
> Process [0]
> inf
> 0
> 0
>