[petsc-users] RCM for ILU?

[Matthew Knepley]

You need --download-superlu  due to licensing restrictions. And you need
the development version.

   Matt
On Feb 18, 2014 11:25 AM, "Qin Lu" <lu_qin_2000 at yahoo.com> wrote:

> Do you mean using "-pc_factor_mat_ordering_type  wbm"? It does not seem
> to be in the manual. What exactly is it? I will try it anyway.
>
> Many thanks,
> Qin
>
>
>   On Tuesday, February 18, 2014 10:11 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.
> 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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