[Trilinos-Users] Symmetric matrices

[Baker, Christopher G.]

Hi Daniel,

This was addressed by Mike some time ago on the mailing list by Mike Heroux:

"Epetra doesn't have support for reduced storage of a symmetric matrix.  We have talked about it from the very beginning, but never had quite enough time and priority to make it happen.  It's actually fairly straight-forward to support it, but working through the details would take time."

The current solution is to forgo optimal storage by storing all of A; or store only half of A and multiply twice (U*x + trans(U)*x, keeping in mind that the diagonal must be stored halved.) Both approaches have their drawbacks; I expect that most people choose the former, for simplicity, improved interoperability with other Epetra-based classes, and reduced communication costs.

Chris



On 11/10/10 12:55 PM, "Daniel Langr" <daniel.langr at gmail.com> wrote:

 Hi all,

how Epetra works with symmetric matrices? Is it possible to store only
lower or upper triangular part? I found nothing about this topic in
documentation.

Thanks,
Daniel