[petsc-users] MatGetLocalSubMatrix Trouble

[Jared Crean]

     Hello Barry,
         Thanks makes sense now.

     Thanks,
         Jared Crean

On 02/15/2016 11:43 PM, Barry Smith wrote:
>    Jared,
>
>     Though it is not properly documented the matrix must have had a call to MatSetLocalToGlobalMapping() before you can call MatCreateLocalRef().
>
>     I'll add a little more error checking and docs.
>
>    Barry
>
> Note that matrices obtained with DMCreateMat() generally have had the local to global mapping already provided to the matrix so you don't need to call it yourself.
>
>
>> On Feb 15, 2016, at 10:31 PM, Jared Crean <jcrean01 at gmail.com> wrote:
>>
>> Hello,
>>     When I try to use MatGetLocalSubMatrix (line 55 of the attached code), I get the following error:
>>
>> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
>> [0]PETSC ERROR: Null argument, when expecting valid pointer
>> [0]PETSC ERROR: Null Object: Parameter # 2
>> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
>> [0]PETSC ERROR: Petsc Release Version 3.6.0, Jun, 09, 2015
>> [0]PETSC ERROR: ./jc3 on a arch-linux2-cxx-debug named k475 by jared Mon Feb 15 23:19:29 2016
>> [0]PETSC ERROR: Configure options --with-clanguage=C++
>> [0]PETSC ERROR: #1 ISL2GCompose() line 117 in /home/jared/build/petsc-3.6.0/src/mat/impls/localref/mlocalref.c
>> [0]PETSC ERROR: #2 MatCreateLocalRef() line 259 in /home/jared/build/petsc-3.6.0/src/mat/impls/localref/mlocalref.c
>> [0]PETSC ERROR: #3 MatGetLocalSubMatrix() line 9686 in /home/jared/build/petsc-3.6.0/src/mat/interface/matrix.c
>> [0]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
>> [0]PETSC ERROR: Null argument, when expecting valid pointer
>> [0]PETSC ERROR: Null Object: Parameter # 2
>> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
>> [0]PETSC ERROR: Petsc Release Version 3.6.0, Jun, 09, 2015
>> [0]PETSC ERROR: ./jc3 on a arch-linux2-cxx-debug named k475 by jared Mon Feb 15 23:19:29 2016
>> [0]PETSC ERROR: Configure options --with-clanguage=C++
>> [0]PETSC ERROR: #4 ISL2GCompose() line 117 in /home/jared/build/petsc-3.6.0/src/mat/impls/localref/mlocalref.c
>> [0]PETSC ERROR: #5 MatCreateLocalRef() line 259 in /home/jared/build/petsc-3.6.0/src/mat/impls/localref/mlocalref.c
>> [0]PETSC ERROR: #6 MatGetLocalSubMatrix() line 9686 in /home/jared/build/petsc-3.6.0/src/mat/interface/matrix.c
>> [0]PETSC ERROR: #7 main() line 55 in /home/jared/build/petsc-3.6.0/src/ksp/ksp/examples/tutorials/jc3.c
>> [0]PETSC ERROR: No PETSc Option Table entries
>> [0]PETSC ERROR: ----------------End of Error Message -------send entire error message to petsc-maint at mcs.anl.gov----------
>> application called MPI_Abort(MPI_COMM_WORLD, 85) - process 0
>>
>>
>>     A did a little digging and found:
>>
>>     Line 117-118 of mlocalref.c are:
>>   PetscValidHeaderSpecific(ltog,IS_LTOGM_CLASSID,2);
>>   PetscValidPointer(cltog,3);
>>
>>     where ltog is the ISLocalToGlobalMapping from (line 259):
>>         A->rmap->mapping
>>
>>     where A is the original matrix, cltog is a reference to the local to global mapping to be created .
>>     The code prints out A, so it appears to be a valid matrix.  Is there something wrong with the way I am using MatGetLocalSubMatrix?
>>
>>     Jared Crean
>>
>>
>> <jc3.c>