OK, well if I get something working before you all do, I will send along 
the code.

Thanks,

-- Boyce

On 9/27/10 12:34 PM, Barry Smith wrote:
>
>     Boyce,
>
>     Don't mess with this bad advice. It is just making your live complicated. 
>  Use a fast MatAXPY() either write it yourself or wait for use.
>
>     Barry
>
> On Sep 27, 2010, at 11:30 AM, Boyce Griffith wrote:
>
>>
>>
>> On 9/27/10 10:47 AM, Hong Zhang wrote:
>>> Boyce,
>>>
>>>> The easiest way I can think of to handle this is to make P^T C P, then
>>>> extract the nonzero
>>>> structure with Mat with GetIJ() and create B. You would have to explicitly
>>>> put zeros in B
>>>> too or else AssemblyEnd() will shrink it. Maybe someone else can think of 
>>>> an
>>>> easier way.
>>>
>>> This is what I would suggest as well.
>>
>> It looks like MatGetRowIJ will do the trick for SeqAIJ matrices, but it 
>> appears that similar functionality does not exist for MPIAIJ matrices. Is 
>> there an approach that you would recommend for the parallel case?
>>
>> Thanks!
>>
>> -- Boyce
>
>
>

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