[Trilinos-Users] Inverse of a sparse matrix

[Martin Vymazal]

Hello Mike,

  since it's a little testing code for the moment, I typically have  
1000 DOF (i.e. the full dense matrix would have 1000x1000 entries). I  
don't think I'll play with meshes bigger than 5000 DOF. For the  
moment, I'm just testing the concept.

  Martin Vymazal

Quoting "Heroux, Michael A" <maherou at sandia.gov>:

> Martin,
>
> How big is your system, typically and at its largest?
>
> Mike
>
>
> On 8/31/10 1:03 PM, "Martin Vymazal" <martin.vymazal at vki.ac.be> wrote:
>
>> Hello Mark,
>>
>>   no, I'm not a physicist. My matrix is a discrete representation of
>> an operator acting between two finite element grids. Wherever I could,
>> I avoided the inversion by solving Ax=b. Unfortunately, now I really
>> need the complete inverse.
>>
>>    Best regards,
>>
>>   Martin Vymazal
>>
>> Quoting Mark Hoemmen <mhoemme at sandia.gov>:
>>
>>> On Aug 31, 2010, at 10:47 AM,
>>> trilinos-users-request at software.sandia.gov wrote:
>>>> Message: 1
>>>> Date: Tue, 31 Aug 2010 00:29:43 +0200
>>>> From: "Martin Vymazal" <martin.vymazal at vki.ac.be>
>>>> Subject: [Trilinos-Users] Inverse of a sparse matrix?
>>>> To: trilinos-users at software.sandia.gov
>>>> Message-ID: <20100831002943.122974kkn7rtlwif at horde.vki.ac.be>
>>>> Content-Type: text/plain; charset=iso-8859-1; DelSp=Yes; format=flowed
>>>>
>>>> Hello,
>>>>
>>>>  I'm sorry if this question was already answered somewhere, but I
>>>> searched and didn't find the answer. I'd like to ask what is the best
>>>> way to compute an inverse of a Epetra__FECrsMatrix. Thank you.
>>>
>>> Are you a physicist, and if so, do you wish to compute specific
>>> elements of the inverse?  If you are just solving linear systems
>>> Ax=b, you never want the inverse.  However, some physics
>>> applications do call for certain elements of the inverse.  If you
>>> only need, say, the diagonal entries of the inverse, there are less
>>> computationally expensive ways to do this than to compute the full
>>> inverse.
>>>
>>> mfh
>>> _______________________________________________
>>> Trilinos-Users mailing list
>>> Trilinos-Users at software.sandia.gov
>>> http://software.sandia.gov/mailman/listinfo/trilinos-users
>>>
>>>
>>
>>
>>
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>
>
>



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