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

[Danyang Su]

Hi Matthew,

Thanks for pointing out. The problem is that vec_natural is always zero 
after calling DMPlexGlobalToNaturalEnd. I am afraid something is missing 
in my code.

Thanks,

Danyang

On 18-11-28 07:34 PM, Matthew Knepley wrote:
> On Wed, Nov 28, 2018 at 8:58 PM Danyang Su via petsc-users 
> <petsc-users at mcs.anl.gov <mailto: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/%7Eknepley/>

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