[petsc-users] Arbitrary ownership IS for a matrix

[Nicolás Barnafi]

Thank you both very much, it is exactly what I needed.

Best regards

On Wed, Mar 9, 2022, 21:19 Matthew Knepley <knepley at gmail.com> wrote:

> On Wed, Mar 9, 2022 at 5:13 PM Barry Smith <bsmith at petsc.dev> wrote:
>
>>
>>   You need to do a mapping of your global numbering to the standard PETSc
>> numbering and use the PETSc numbering for all access to vectors and
>> matrices.
>>
>>    https://petsc.org/release/docs/manualpages/AO/AOCreate.html provides
>> one approach to managing the renumbering.
>>
>
> You can think of this as the mapping to offsets that you would need in any
> event to store your values (they could not be directly addressed with your
> random indices).
>
>   Thanks,
>
>      Matt
>
>
>>   Barry
>>
>>
>> On Mar 9, 2022, at 3:42 PM, Nicolás Barnafi <nabw91 at gmail.com> wrote:
>>
>> Hi community,
>>
>> I have an application with polytopal meshes (elements of arbitrary shape)
>> where the distribution of dofs is not PETSc friendly, meaning that it is
>> not true that cpu0 owns dofs [0,a), then cpu1 owns [a,b) and so on, but
>> instead the distribution is in fact random. Another important detail is
>> that boundary dofs are shared, meaning that if dof 150 is on the boundary,
>> each subdomain vector has dof 150.
>>
>> Under this considerations:
>>
>> i) Is it possible to give an arbitrary mapping to the matrix structure or
>> is the blocked distribution hard coded?
>> ii) Are the repeated boundary dofs an issue when computing a Fieldsplit
>> preconditioner in parallel?
>>
>> Best regards,
>> Nicolas
>>
>>
>>
>
> --
> 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
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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