SeqSBAIJ with cholesky

Julian julvar at
Tue Oct 24 13:07:15 CDT 2006


I am trying to use -pc_type cholesky with a SBAIJ (MatCreateSeqSBAIJ)
Unless I specifically ask for it, its not going to reorder the matrix,
right? I've been used to calling it 'renumbering' the matrix but I'm
guessing its the same thing - rearranging the rows and columns so the
bandwidth of the matrix is reduced, am I correct?

>From this earlier email, I'm understanding that the sbaij format does not
support reordering? Btw, I tried it anyway.. And it gave some segmentation
violation error...maybe it can catch the incompatibility earlier on, so that
the real problem is more obvious.
Do you plan on providing the reordering feature for sbaij in the future?
Almost all structural fem codes deal with symmetric positive semi definite
matrices. So, that would be a very useful feature... 
Also why do you say that the aij format is more efficient than the sbaij
format? I would have thought utilizing the symmetry would make the sbaij
format more efficient.
is the sbaij format not supported in parallel?

With how it stands right now, is there any other solver supported by petsc
(external or otherwise) that lets me use reordering with the symmetric
matrix ?


> -----Original Message-----
> From: owner-petsc-users at 
> [mailto:owner-petsc-users at] On Behalf Of Hong Zhang
> Sent: Wednesday, October 11, 2006 2:14 PM
> To: petsc-users at
> Subject: RE: General matrix interative solver
> Julian,
> If you do not perform matrix reordering, you can use petsc 
> sbaij format, which only stores the upper triangular entries. 
> aij format has more algorithmic options and is more efficient 
> and supports matrix reordering.
> Hong

More information about the petsc-users mailing list