[petsc-users] Newbie question : iterative solver - algorithm and performance

[Patrick Sanan]

On Wed, Feb 15, 2017 at 8:26 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
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>> On Feb 15, 2017, at 7:03 AM, lixin chu <lixin_chu at yahoo.com> wrote:
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>> I think the chapter 4 of the user manual more or less answers my first question already ...
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>> rgds
>> lixin
>>
>>
>> On Wednesday, 15 February 2017, 14:40, lixin chu <lixin_chu at yahoo.com> wrote:
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>>
>> Hello,
>> New to PETSc, appreciate any help -
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>> I have done some experiment with MUMPS (the direct solver for sparse matrix), and very interested to try out PETSc now. I have a large sparse symmetric matrix (3 millions x 3 millions, complex data type).
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>> Some questions I have:
>> - I am assuming that I should select one algorithm of "Krylov methods", which algorithm is a good option, GMRES, CG, or others ? (I am not a domain expert, but helping developing a program to test the matrix).
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>    GMRES is a "safe" choice. You can try -ksp_type cg   -ksp_cg_type symmetric  (or if the matrix is hermitian; i.e. transpose A = complex conjugate of A  then type hermitian instead of symmetric).
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>> - do all the algorithms support distributed architecture (multiple machines, multiple cores)
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>     Yes
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>> - are there any performance test data ? (total run time for example)
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>    Run your code with -view_summary and it will print information at the end about where it has spent the time doing the computation.
Barry probably meant -log_view here.
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>> thank you very much,
>> LX
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>>
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