[petsc-dev] More on FV overlap cells and Fortran

[Matthew Knepley]

On Wed, Apr 8, 2015 at 11:02 PM, Adrian Croucher <a.croucher at auckland.ac.nz>
wrote:

>
>  I apologize for taking so long. I got caught up in the SIAM Meeting. I
>> have
>> pushed
>>
>>    PetscErrorCode DMPlexGetPointGlobalField(DM dm, PetscInt point,
>> PetscInt
>> field, PetscInt *start, PetscInt *end)
>>
>> to next. This corresponds with the public interface naming scheme Jed
>> started.
>>
>
> Thanks Matt.
>
> I'm not sure if I understand how to use this correctly, because so far I
> have just got segfaults.
>
> To test it out I tried using the C version in a copy of
> src/dm/impls/plex/examples/tutorials/ex1.c. After the call to
> DMSetDefaultSection(dm, section), I inserted the lines:
>
>   ierr = DMPlexGetPointGlobalField(dm, 0, 1, &istart, &iend);
> CHKERRQ(ierr);
>   printf("start: %d end: %d", istart, iend);
>
> I figured this would give me the start and end locations of the field 1
> ("v") at point 0 (the first cell?), which should be ok because v is defined
> on cells. So for dim = 2 I'd expect istart = 0 and iend = 2- is that right?
>
> Instead I get:
>

Is it possible that you have not created the global section yet? I do not
use the normal interface here, which creates it
automatically, to speed things up. You can just call
DMPlexGetDefaultGlobalSection() before the call.

  Thanks,

     Matt


> [0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation,
> probably memory access out of range
> [0]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger
> [0]PETSC ERROR: or see http://www.mcs.anl.gov/petsc/
> documentation/faq.html#valgrind
> [0]PETSC ERROR: or try http://valgrind.org on GNU/linux and Apple Mac OS
> X to find memory corruption errors
> [0]PETSC ERROR: likely location of problem given in stack below
> [0]PETSC ERROR: ---------------------  Stack Frames
> ------------------------------------
> [0]PETSC ERROR: Note: The EXACT line numbers in the stack are not
> available,
> [0]PETSC ERROR:       INSTEAD the line number of the start of the function
> [0]PETSC ERROR:       is given.
> [0]PETSC ERROR: [0] PetscSectionGetOffset line 1205
> /home/acro018/software/PETSc/code/src/vec/is/utils/vsectionis.c
> [0]PETSC ERROR: [0] DMPlexGetGlobalFieldOffset_Private line 408
> /home/acro018/software/PETSc/code/include/petsc-private/dmplexi
> mpl.h
> [0]PETSC ERROR: [0] DMPlexGetPointGlobalField line 367
> /home/acro018/software/PETSc/code/src/dm/impls/plex/plexpoint.c
>
> Cheers, Adrian
>
> --
> Dr Adrian Croucher
> Senior Research Fellow
> Department of Engineering Science
> University of Auckland, New Zealand
> email: a.croucher at auckland.ac.nz
> tel: +64 (0)9 923 84611
>
>


-- 
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
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