[petsc-users] Arbitrary ownership IS for a matrix

[Barry Smith]

  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 <https://petsc.org/release/docs/manualpages/AO/AOCreate.html> provides one approach to managing the renumbering.

  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

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