[petsc-users] Convert MatNest to MatAIJ

[Jed Brown]

How did you get the MatNest?

What you describe is the right approach, but proper preallocation is messy
in the general case. There is a partial implementation in petsc-dev, but it
needs to be finished/debugged.
On Oct 10, 2012 8:45 AM, "Thomas Witkowski" <thomas.witkowski at tu-dresden.de>
wrote:

>  You are right. But what if a have a MATNEST and i must convert it to
> MATAIJ. Any better way than what I wrote in my first mail?
>
> Thomas
>
> Am 10.10.2012 15:33, schrieb Jed Brown:
>
> The best way, by far, is to assemble the matrix as AIJ if that is what you
> want to use. See MatGetLocalSubMatrix and SNES ex28. Using MATNEST should
> he a run-time choice.
> On Oct 10, 2012 8:30 AM, "Thomas Witkowski" <
> thomas.witkowski at tu-dresden.de> wrote:
>
>> Is there a fast way to convert a MatNest to a MatAIJ? I tried to use
>> MatConvert, but it seems that this convert is not yet implemented. As I
>> need this functionality to factorize the nested matrix with MUMPS, is there
>> any better way than to extract the nested matrices, iterate over all rows
>> of these matrices and use MatSetValues to add them again to the final
>> MatAIJ?
>>
>> Thomas
>>
>
>
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