"Jose E. Roman" <[email protected]> writes:

> Hi Jed,
>
> I saw you added spectral partitioning
> https://bitbucket.org/petsc/petsc/commits/fc1bef75356

This was entirely based on Matt's code, which included some HSL code
that we don't have a license to include.  I refactored to avoid that.

> One thing I do not understand is why is it in MatOrdering. Shouldn't
> it be in MatPartitioning? My understanding was that MatOrdering was
> intended for fill-reducing orderings for PCFactor.
>
> I always wanted to do spectral partitioning with SLEPc. I started years ago 
> with a Matlab script that makes spectral bisection recursively for log2(np) 
> levels, using a generic eigensolver (eigs) in each level. It works well, but 
> it is necessary to add a refinement step between each level 
> (Fiduccia-Mattheyses). That is one of the reasons why I did not even start 
> the implementation in SLEPc.
>
> On the other hand, this recent paper formulates the problem differently and 
> uses LOBPCG to solve a generalized eigenproblem:
>
> [1] E. Vecharynski, Y. Saad, and M. Sosonkina. Graph partitioning using 
> matrix values for preconditioning symmetric positive definite systems. SIAM 
> Journal on Scientific Computing, 36(1):A63–A87, 2014.
> http://epubs.siam.org/doi/abs/10.1137/120898760

Interesting.

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