[petsc-users] Segmentation Violation in getting DMPlex coordinates

[Matthew Knepley]

On Sat, Apr 28, 2018 at 2:08 AM, Danyang Su <danyang.su at gmail.com> wrote:

> Hi All,
>
> I use DMPlex and need to get coordinates back after distribution. However,
> I always get segmentation violation in getting coords values in the
> following codes if using multiple processors. If only one processor is
> used, it works fine.
>
> For each processors, the off value starts from 0 which looks good. I also
> tried 0-based index, which gives the same error. Would any one help to
> check what is wrong here?
>
>  idof           1 off           0
>  idof           2 off           0
>  idof           1 off           2
>  idof           2 off           2
>  idof           1 off           4
>  idof           2 off           4
>  idof           1 off           6
>  idof           2 off           6
>  idof           1 off           8
>  idof           2 off           8
>
>
>       DM :: distributedMesh, cda
>       Vec :: gc
>       PetscScalar, pointer :: coords(:)
>       PetscSection ::  cs
>
>       ...
>
>       call DMGetCoordinatesLocal(dmda_flow%da,gc,ierr)
>       CHKERRQ(ierr)
>
>       call DMGetCoordinateDM(dmda_flow%da,cda,ierr)
>       CHKERRQ(ierr)
>
>       call DMGetDefaultSection(cda,cs,ierr)
>       CHKERRQ(ierr)
>
>       call PetscSectionGetChart(cs,istart,iend,ierr)
>       CHKERRQ(ierr)
>
>       !c get coordinates array
>       call DMDAVecGetArrayF90(cda,gc,coords,ierr)
>

You cannot call DMDA function if you have a DMPlex. You jsut call
VecGetArrayF90()

   Matt


>       CHKERRQ(ierr)
>
>       do ipoint = istart, iend-1
>
>         call PetscSectionGetDof(cs,ipoint,dof,ierr)
>         CHKERRQ(ierr)
>
>         call PetscSectionGetOffset(cs,ipoint,off,ierr)
>         CHKERRQ(ierr)
>
>         inode = ipoint-istart+1
>
>         if (cell_coords == coords_xyz) then
>           nodes(inode)%x = coords(off+1)
>           nodes(inode)%y = coords(off+2)
>           nodes(inode)%z = coords(off+3)
>         else if (cell_coords == coords_xy) then
>           nodes(inode)%x = coords(off+1)
>           nodes(inode)%y = coords(off+2)
>           nodes(inode)%z = 0.0d0
>         else if (cell_coords == coords_yz) then
>           nodes(inode)%x = 0.0d0
>           nodes(inode)%y = coords(off+1)
>           nodes(inode)%z = coords(off+2)
>         else if (cell_coords ==coords_xz) then
>           nodes(inode)%x = coords(off+1)
>           nodes(inode)%y = 0.0d0
>           nodes(inode)%z = coords(off+2)
>         end if
>       end do
>
>       call DMDAVecRestoreArrayF90(cda,gc,coords,ierr)
>       CHKERRQ(ierr)
>
> Thanks,
>
> Danyang
>
>
>


-- 
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.caam.rice.edu/~mk51/>
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