[petsc-users] Preconditioners for a FEM model

[jifeng zhao]

Yes ex13 works for me. Could you let me know where can I download the
program and how can I add options at the runtime? Thank you so much.

Jifeng


On Thu, Jul 3, 2014 at 12:13 PM, murat keçeli <keceli at gmail.com> wrote:

> Hi Jifeng,
>
> You can start with ex13 in SLEPc to see how it works for your case. You
> would need MUMPS as a direct solver. Section 3.4.5 is the relevant section
> in SLEPc manual (Campos and Roman 2012 paper would be very helpful if you
> need more details). Let me know if it works for you and we can continue
> from there.
>
> Thanks,
> Murat
>
>
> On Thu, Jul 3, 2014 at 12:18 AM, jifeng zhao <
> jifengzhao2015 at u.northwestern.edu> wrote:
>
>> Hi Murat,
>>
>> Yes, that sounds great. I would like to have a try. Would you let me know
>> how to use it on top of SLEPC and PETSC in more details?
>>
>> Cheers,
>> Jifeng Zhao
>>
>>
>> On Wed, Jul 2, 2014 at 9:41 PM, murat keçeli <keceli at gmail.com> wrote:
>>
>>> Hi Jifeng,
>>>
>>> I think your application is suitable for the SIPs method, see attached
>>> paper.  We have improved it recently, so that it can handle very
>>> large (500k by 500k with more than 3.e7 nonzeros) sparse matrices.Current
>>> version of SIPs is basically adding a second layer of parallelism on top of
>>> SLEPc's shift and invert method. Let me or Hong Zhang (cc, the developer of
>>> SIPs) know, if you would like to give it a try.
>>>
>>> Murat Keceli
>>>
>>>
>>> On Wed, Jul 2, 2014 at 4:46 PM, jifeng zhao <
>>> jifengzhao2015 at u.northwestern.edu> wrote:
>>>
>>>> Hello all,
>>>>
>>>> I am working on solving a generalized eigenvalue problem with SLEPC and
>>>> PETSC.
>>>>
>>>> *K* x = lamda *M* x
>>>>
>>>> I attached the sparsity pattern of matrix *M* (*K* is the same). It is
>>>> a FEM model. It is so sparse is because of constraints.
>>>>
>>>> I have tried two things:
>>>>
>>>> 1. Krylov-Schur and exact shift-and-invert (I will try MUMPS in
>>>> future). It works. But I am worrying that it is less parrallelable, when
>>>> the problem contains millions of degree of freedom.
>>>>
>>>> 2. JD with Jacobi preconditioner. It could work, but a lot of tuning
>>>> needs to be done in terms of RTOL, max_iteration_number. And sometimes I
>>>> suffer from a stagnated solution, and can't obtain accurate result.
>>>>
>>>> Does anybody know that for my specific case of matrix sparsity, is
>>>> there any thing I can do to speed up my direct solver (Krylov-Schur)?
>>>>
>>>> Is there any recommended preconditioners I could try on, for the case
>>>> of JD? There are a lot of preconditioners in HYPRE library.
>>>>
>>>> Thank you in advance!
>>>> [image: Inline image 1]
>>>>  --
>>>> Jifeng Zhao
>>>> PhD candidate at Northwestern University, US
>>>> Theoretical and Applied Mechanics Program
>>>>
>>>
>>>
>>
>>
>> --
>> Jifeng Zhao
>> PhD candidate at Northwestern University, US
>> Theoretical and Applied Mechanics Program
>>
>
>


-- 
Jifeng Zhao
PhD candidate at Northwestern University, US
Theoretical and Applied Mechanics Program
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