[petsc-users] RCM for ILU?

Matthew Knepley knepley at gmail.com
Tue Feb 18 11:04:55 CST 2014

On Feb 18, 2014 10:12 AM, "Jed Brown" <jed at jedbrown.org> wrote:
> Qin Lu <lu_qin_2000 at yahoo.com> writes:
> > RCM did not help much for my case. This case represents some strong
> > connectivities in channels. I am wondering if PETSc has some
> > reordering algorithm or solver that is not based on connectivity
> > graph, but is based on connectivity strength (such as percolation type
> > of reordering). Any information is appreciated.    Thanks, Qin
> There isn't such an ordering, but it would be a welcome contribution.

Not exactly. You can try 'wbm' in next.


> One challenge is that features like anisotropy are not necessarily
> apparent in the matrix entries.  In that case, and for vector-valued
> problems, you would ideally use a better strength-of-connection measure.
> If you computed a strength-of-connection, then thresholded (or used edge
> weights as a "priority"), followed by something like an RCM ordering,
> you could find something good for low-fill incomplete factorization in
> problems with hidden anisotropy.
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