[petsc-dev] MatXXXSetPreallocation and -mat_new_nonzero_allocation_error

Barry Smith bsmith at mcs.anl.gov
Thu Apr 22 15:05:47 CDT 2010

On Apr 22, 2010, at 2:27 PM, Jed Brown wrote:

> On Thu, 22 Apr 2010 14:07:06 -0500, Barry Smith <bsmith at mcs.anl.gov>  
> wrote:
>>   I don't understand how knowing the preallocation for SBAIJ give you
>> an efficient way to know the preallocation for BAIJ?  Say you have
>> 20,000 processors can you efficiently get the information where it is
>> needed? Are you willing to write the code to do that?
> Ah, you're right, there's no way to preallocate BAIJ from SBAIJ  
> without
> indices (it's not just hard, there isn't enough information).  That
> seems to have been a bad example.  But there is a clear way to
> preallocate AIJ from BAIJ and that code is written (in
> SlicedGetMatrix(), if not elsewhere).  So what about having AIJ
> implement BAIJ preallocation,

     That should be ok.


> consistent with the theme of BAIJ
> interfaces merely providing more structured information?
> Jed

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