[Trilinos-Users] Large Generalized Symmetric Complex Eigenvalue Problem: From ARPACK to Anasazi?

[Klaus Zimmermann]

Heidi, Mike,

thanks your response time is incredible!
You are exactly right with the spectral transformation. Should have 
mentioned.
We are doing shift-and-invert. I guess this is still applicable?

Thanks again,
Klaus

On 07.08.10 00:23, Thornquist, Heidi K wrote:
> Hi Klaus,
>
> For now we'd suggest Anasazi (BKS), Tpetra, Belos (GMRES), Tifpack 
> (for preconditioning).  Since Tifpack is a
> domain decomposition incomplete LU, it won't take nearly as much 
> memory as Pardiso.  This is because it
> is not performing an full factorization of the matrix, just an 
> incomplete LU factorization of the parts of the domain that
> are on each processor.  When you are using ARPACK, I'm assuming that 
> you are using a spectral transformation,
> which is why you need the linear solver.  If so, which linear solver 
> did you use with ARPACK?
>
> Thanks,
> Heidi
>
>
> On 8/6/10 4:13 PM, "Klaus Zimmermann" 
> <klaus.zimmermann at physik.uni-freiburg.de> wrote:
>
>     Mike,
>
>     thanks for your quick reply!
>     I am glad to hear of these improvements. If I understand you correctly
>     for now you'd suggest
>     Anasazi, Tpetra, Belos, right?
>     Then there is the question of the preconditioner: In our legacy
>     code we
>     did a LU factorization
>     (via pardiso) which quickly led to storage requirements on the
>     order of
>     50 gb. This is unfortunately
>     prohibitive for the 16 gb of ram/node on the grid. We used to use
>     out of
>     core functionality for the
>     solver.
>     Is such out of core stuff available for Belos as well, or will Tifpack
>     reduce the amount of memory
>     needed so much I don't have to worry?
>     For reference  the matrices we deal with right now are on the order of
>     n=1e8, complex symmetric
>     with about 0.5% non zero elements.
>
>     Klaus
>
>     On 06.08.10 23:53, Heroux, Michael A wrote:
>     > Klaus,
>     >
>     > The software stack that supports complex is growing quickly.
>      Belos already
>     > supports complex for Krylov methods for linear systems.  There is
>     a new
>     > package called Tifpack that supports complex to do domain
>     decomposition with
>     > ILU and related preconditioners.  So, using Trilinos 10.4 (the
>     current
>     > release), there is a better answer than Komplex for iterative linear
>     > solvers.
>     >
>     > In the next version of Trilinos (Oct 2010), we plan to have
>     Amesos2 and KLU
>     > 2, which support complex.  How much of the linking support to complex
>     > versions of MUMPS, UMFPACK, etc. will be done by October is not
>     clear right
>     > now, but we are moving in the right direction.
>     >
>     > BTW, all of the support for complex comes from using templated
>     scalar types
>     >
>     > Mike
>     >
>     > On 8/6/10 4:41 PM, "Klaus Zimmermann"
>     > <klaus.zimmermann at physik.uni-freiburg.de>  wrote:
>     >
>     >
>     >> Hi All,
>     >>
>     >> for my ab initio quantum calculations I have to find some
>     eigenvalues
>     >> for large, sparse complex symmetric generalized eigenvalue problems.
>     >> I would really like to move from our legacy ARPACK fortran code to a
>     >> more modern code base
>     >> in order to make use of our local MPI based grid. I am a bit
>     overwhelmed
>     >> by the choices. But I now think
>     >> I boiled my possibilities down to Anasazi or SLEPc. I'd prefer
>     to go the
>     >> C++ way.
>     >> However I understand the support for complex systems in the linear
>     >> solver part is limited.
>     >>
>     >> What would be the best way to go about tackling this kind of
>     problem?
>     >> Right now I am thinking: Anasazi<Tpetra, BlockKrylovSchur>  +
>     >> (Komplex+Amesos+MUMPS).
>     >> Is this reasonable?
>     >>
>     >> Thanks for any hints in advance!
>     >>
>     >> Regards,
>     >> Klaus Zimmermann
>     >>
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>     >>
>     >
>     >
>
>
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