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

[Yujie]

thanks :)

On Wed, Dec 31, 2008 at 9:29 AM, Matthew Knepley <knepley at gmail.com> wrote:

> 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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