[petsc-users] SNESFAS for an unstructured mesh

[Khai Pham]

Hi Lawrence and Vijay,

Thanks for the suggestion. I will look at the ex65 and start from there.



On Wed, Jun 29, 2016 at 3:41 PM, Vijay S. Mahadevan <vijay.m at gmail.com>
wrote:

> >> Thanks for your response. Is DMMoad is other special kind of data
> structure in Petsc?
>
> DMMoab is a concrete implementation of the DM object, which uses MOAB
> mesh database underneath.
>
> > Would it be possible to use FAS without using petsc DM/DMPlex by adding
> extra code?
>
> If you have your own mesh handling code, as Lawrence suggests, use a
> DMShell object and create appropriate wrapper routines that utilizes
> your home grown API underneath. There is a linear solver example with
> DMShell, which should help you get started. Instead of the DA object
> reference used in the shell implementation, you can replace it with
> your own structures and context.
>
>
> http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex65.c.html
>
> Vijay
>
> On Wed, Jun 29, 2016 at 1:58 PM, Lawrence Mitchell
> <lawrence.mitchell at imperial.ac.uk> wrote:
> >
> >
> >> On 29 Jun 2016, at 19:47, Khai Pham <khaipham at utexas.edu> wrote:
> >>
> >> Thanks for your response. Is DMMoad is other special kind of data
> structure in Petsc? I'd like to use the petsc FAS for the finite element
> code in our group and all the data structure for mesh topology is all set.
> Thus I try to avoid all petsc data structure. As far as I know the FAS will
> construct the coarse solution based on DM for structured grid and DMPlex
> for unstructured grid as in ex12. Would it be possible to use FAS without
> using petsc DM/DMPlex by adding extra code? How much effort would you
> estimate? Thanks !
> >
> > You can use a DMShell and just implement the needed grid transfer
> operations using your own data structures and then use the DMShellSetXXX
> interfaces to hook them up.
> >
> > Lawrence
>
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