[petsc-users] any good references on matrix scaling
Jed Brown
jedbrown at mcs.anl.gov
Thu Sep 12 14:00:10 CDT 2013
Umut Tabak <u.tabak at tudelft.nl> writes:
> Dear all,
>
> I am looking for some references for matrix scaling where I would like
> to improve the conditioning of a block representation such as
>
> A C
> C^T B
>
> where the terms in A and B blocks are of very different orders, such as
> A is of 1e+8 and B for instance is of order 1e-4 . The ratios can get
> even worse but not better on the problems I tried.
I recommend non-dimensionalizing (i.e., choosing units) so the system is
better scaled.
> I am trying have an overview for some cheap conditioning approaches for
> this problem.
Most preconditioners use the diagonal enough to fix the disparate
scales. If you are using full-space iteration with PCFIELDSPLIT, you'll
likely have to scale the variables first. You can always use Schur
complement reduction.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 835 bytes
Desc: not available
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130912/545c862e/attachment.pgp>
More information about the petsc-users
mailing list