get several submatrices from several matrices and combine submatrices into another matrix

[Matthew Knepley]

Yes.

   Matt

On Wed, Dec 31, 2008 at 11:25 AM, Yujie <recrusader at gmail.com> wrote:

> Dear Matthew:
>
> thank you very much. Regarding my problem about MatAXPY() for MPIDense, I
> have checked SEQDense has this function. To my knowledge, in each node,
> MPIDense's format is SEQDense, right? if it is, I should ba able to write a
> MPIDense-based function using SEQDense? thanks  a lot.
>
> Regards,
> Yujie
>
>
> On Wed, Dec 31, 2008 at 8:56 AM, Matthew Knepley <knepley at gmail.com>wrote:
>
>> Yes, you can have 0 length IS arguments.
>>
>>   Matt
>>
>>
>> On Wed, Dec 31, 2008 at 10:21 AM, Yujie <recrusader at gmail.com> wrote:
>>
>>> Hi, PETSc Developers
>>>
>>> In parallel mode, I have 3 MPIDense matrices, A1, A2, A3. Now, I need to
>>> exact submatrices B1, B2, B3 in parallel mode from A1, A2, A3 respectively.
>>> I know I should use MatGetSubMatrix(). My problem is in
>>>
>>> MatGetSubMatrix(Mat mat,IS isrow,IS iscol,PetscInt csize,MatReuse cll,Mat *newmat)
>>>
>>> , the parameter "isrow" means "rows this processor should obtain". if Bi
>>> in some nodes (cpus) of the cluster (Ai have rows in them) don't have rows,
>>> is it work?
>>>
>>> After getting Bi, I will create MPIDense-based C and combine them into C
>>> like
>>>
>>>      B1
>>> C= B2
>>>      B3
>>> MatGetRow();
>>> MatSetValues() should work, right?
>>>
>>> Could you give me some comments about these operations? thanks a lot.
>>> Happy new year!
>>>
>>> Regards,
>>> Yujie
>>>
>>
>>
>>
>> --
>> What most experimenters take for granted before they begin their
>> experiments is infinitely more interesting than any results to which their
>> experiments lead.
>> -- Norbert Wiener
>>
>
>


-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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