[petsc-users] how to check if cell is local owned in DMPlex

[Danyang Su]

On 18-03-02 10:58 AM, Matthew Knepley wrote:
> On Fri, Mar 2, 2018 at 1:41 PM, Danyang Su <danyang.su at gmail.com 
> <mailto:danyang.su at gmail.com>> wrote:
>
>
>     On 18-02-19 03:30 PM, Matthew Knepley wrote:
>>     On Mon, Feb 19, 2018 at 3:11 PM, Danyang Su <danyang.su at gmail.com
>>     <mailto:danyang.su at gmail.com>> wrote:
>>
>>         Hi Matt,
>>
>>         Would you please let me know how to check if a cell is local
>>         owned? When overlap is 0 in DMPlexDistribute, all the cells
>>         are local owned. How about overlap > 0? It sounds like
>>         impossible to check by node because a cell can be local owned
>>         even if none of the nodes in this cell is local owned.
>>
>>
>>     If a cell is in the PetscSF, then it is not locally owned. The
>>     local nodes in the SF are sorted, so I use
>>     PetscFindInt
>>     (http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscFindInt.html
>>     <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscFindInt.html>).
>     Hi Matt,
>
>     Would you please give me a little more about how to mark the ghost
>     cells when overlap > 0? What do you mean a cell is in the PetscSF?
>     I use PetscSFView to export the graph (original mesh file
>     pile.vtk) and it exports all the cells, including the ghost cells
>     (PETScSFView.txt).
>
>
> Yes, I will send you some sample code when I get time. The first 
> problem is that you are looking at a different PetscSF. This looks 
> like the
> one returned by DMPlexDistribute(). This is mapping the serial mesh to 
> the parallel mesh. You want
>
> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DM/DMGetPointSF.html
>
> Then you can look at
>
> https://bitbucket.org/petsc/petsc/src/1788fc36644e622df8cb1a0de85676ccc5af0239/src/dm/impls/plex/plexsubmesh.c?at=master&fileviewer=file-view-default#plexsubmesh.c-683
>
> I get the pointSF, get out the list of leaves, and find points in it 
> using PetscFindInt()
Hi Matt,
By using the local dm, I can get the PetscSF I want, as shown below. Now 
I need to get the number of ghost cells or local cells (here 4944) or 
number of leaves (here 825) for each processor. I try to use 
PetscSFGetGraph to get number of leaves in Fortran. After including 
"petscsf.h", I got compilation error saying "You need a ISO C conforming 
compiler to use the glibc headers". Is there any alternative way to do 
this? I do not need the ghost-neighbor mapping, but just the number of 
local owned cells.

   [0] Number of roots=11449, leaves=825, remote ranks=1
   [0] 4944 <- (1,0)
   [0] 4945 <- (1,28)
   [0] 4946 <- (1,56)
...
   [1] Number of roots=11695, leaves=538, remote ranks=1
   [1] 5056 <- (0,21)
   [1] 5057 <- (0,43)
   [1] 5058 <- (0,65)
   [1] 5059 <- (0,87)

In file included from /usr/include/features.h:375:0,
                  from /usr/include/stdio.h:28,
                  from 
/home/dsu/Soft/PETSc/petsc-3.8.3/include/petscsys.h:175,
                  from /home/dsu/Soft/PETSc/petsc-3.8.3/include/petscsf.h:7,
                  from ../../solver/solver_ddmethod.F90:4837:
/usr/include/x86_64-linux-gnu/sys/cdefs.h:30:3: error: #error "You need 
a ISO C conforming compile\
r to use the glibc headers"
  # error "You need a ISO C conforming compiler to use the glibc headers"

Thanks,

Danyang
>
>   Thanks,
>
>     Matt
>
>     Thanks,
>
>     Danyang
>>
>>       Thanks,
>>
>>         Matt
>>
>>         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/%7Emk51/>
>
>
>
>
> -- 
> 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/%7Emk51/>

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