[petsc-users] Error: DM global to natural SF was not created when DMSetUseNatural has already been called

[Matthew Knepley]

On Wed, Nov 28, 2018 at 8:58 PM Danyang Su via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Dear All,
>
> I got the following error when using DMPlexGlobalToNatural function
> using 1 processor.
>

We do not create that mapping on 1 proc because the orderings are the same.
Reordering happens
when we redistribute.

  Thanks,

     Matt


> [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> [0]PETSC ERROR: Object is in wrong state
> [0]PETSC ERROR: DM global to natural SF was not created.
> You must call DMSetUseNatural() before DMPlexDistribute().
>
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> for trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.10.2, Oct, 09, 2018
>
> The same code does not return error when using more than 2 processors,
> however, the vec_natural is always zero after calling
> DMPlexGlobalToNaturalEnd.
>
>
> DMSetUseNatural() has already been used before calling DMPlexDistribute.
> The code section looks like below
>
>       if (rank == 0) then
>
>          call DMPlexCreateFromCellList(Petsc_Comm_World,ndim,0,0,       &
> num_nodes_per_cell,                                        &
> Petsc_False,dmplex_cells,ndim,                        &  !use Petsc_True
> to create intermediate mesh entities (faces, edges),
> dmplex_verts,dmda_flow%da,ierr)
>          CHKERRQ(ierr)
>
>       end if
>
>        !c Set the flag for creating a mapping to the natural order on
> distribution
>        call DMSetUseNatural(dmda_flow%da,PETSC_TRUE,ierr)
>        CHKERRQ(ierr)
>
>        !c distribute mesh over processes
>        call DMPlexDistribute(dmda_flow%da,stencil_width,                &
>                              PETSC_NULL_SF, distributedMesh,ierr)
>
>        CHKERRQ(ierr)
>
>        !c destroy original global mesh after distribution
>        if (distributedMesh /= PETSC_NULL_DM) then
>          call DMDestroy(dmda_flow%da,ierr)
>          CHKERRQ(ierr)
>          !c set the global mesh as distributed mesh
>          dmda_flow%da = distributedMesh
>        end if
>
>        ...
>
>          call DMPlexCreateSection(dmda_flow%da,dmda_flow%dim,           &
> numFields,pNumComp,pNumDof,           &
> numBC,pBcField,                       &
> pBcCompIS,pBcPointIS,                 &
> PETSC_NULL_IS,                        &
>                                   section,ierr)
>          CHKERRQ(ierr)
>
>          call PetscSectionSetFieldName(section,0,'flow',ierr)
>          CHKERRQ(ierr)
>
>
>          call DMSetSection(dmda_flow%da,section,ierr)
>          CHKERRQ(ierr)
>
>          call PetscSectionDestroy(section,ierr)
>          CHKERRQ(ierr)
>
>          call DMSetUp(dmda_flow%da,ierr)
>          CHKERRQ(ierr)
>
>       ...
>
>
>        !c global - natural order
>
>        call DMCreateLocalVector(dmda_flow%da,vec_loc,ierr)
>        CHKERRQ(ierr)
>
>        call DMCreateGlobalVector(dmda_flow%da,vec_global,ierr)
>        CHKERRQ(ierr)
>
>        call DMCreateGlobalVector(dmda_flow%da,vec_natural,ierr)
>        CHKERRQ(ierr)
>
>        !c zero entries
>        call VecZeroEntries(vec_loc,ierr)
>        CHKERRQ(ierr)
>
>        !Get a pointer to vector data when you need access to the array
>        call VecGetArrayF90(vec_loc,vecpointer,ierr)
>        CHKERRQ(ierr)
>
>        do inode = 1, num_nodes
>          vecpointer(inode) = node_idx_lg2pg(inode) !vector value using
> PETSc global order, negative ghost index has been reversed
>        end do
>
>        !Restore the vector when you no longer need access to the array
>        call VecRestoreArrayF90(vec_loc,vecpointer,ierr)
>        CHKERRQ(ierr)
>
>        !Insert values into global vector
>        call DMLocalToGlobalBegin(dmda_flow%da,vec_loc,INSERT_VALUES,    &
>                                  vec_global,ierr)
>        CHKERRQ(ierr)
>
>        call DMLocalToGlobalEnd(dmda_flow%da,vec_loc,INSERT_VALUES,      &
>                                  vec_global,ierr)
>        CHKERRQ(ierr)
>
>
>        !c global to natural ordering
>        call DMPlexGlobalToNaturalBegin(dmda_flow%da,vec_global,         &
>                                        vec_natural,ierr)
>        CHKERRQ(ierr)
>
>        call DMPlexGlobalToNaturalEnd(dmda_flow%da,vec_global,           &
>                                      vec_natural,ierr)
>        CHKERRQ(ierr)
>
>
> Is there anything missing in the code that DMPlexGlobalToNatural... does
> not work properly?
>
> 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.cse.buffalo.edu/~knepley/>
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