[petsc-users] MatAXPY Segmentation violation

[Jelena Slivka]

Thank you very much! Using MatDuplicate solved the problem.




On Sun, Dec 30, 2012 at 4:52 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> You might rather use MatDuplicate(similarity,MAT_DO_NOT_COPY_VALUES,&aux).
>
> Can you try these?
>
> 1. using the debugger to get a stack trace
> 2. run in valgrind to check for memory errors
> 3. set up a test case so we can reproduce
>
>
>
> On Sat, Dec 29, 2012 at 9:41 PM, Jelena Slivka <slivkaje at gmail.com> wrote:
>
>> Hello,
>>
>> I am experiencing the strange behavior when calling the MatAXPY function.
>> Here is my code:
>> matrix similarity is a square matrix (n=m)
>> I create the matrix aux that has all zero elements, except for the
>> diagonal. The elements of the diagonal in matrix aux are sums of rows in
>> matrix similarity.
>>
>>     MatSetFromOptions(similarity);
>>     int n, m;
>>     MatGetSize(similarity, &n, &m);
>>
>>     Vec tmp;
>>     VecCreate(PETSC_COMM_WORLD, &tmp);
>>     VecSetSizes(tmp, PETSC_DECIDE, n);
>>     VecSetFromOptions(tmp);
>>     MatGetRowSum(similarity, tmp);
>>
>>     Mat aux;
>>     MatCreate(PETSC_COMM_WORLD, &aux);
>>     MatSetSizes(aux, PETSC_DECIDE, PETSC_DECIDE, n, m);
>>     MatSetFromOptions(aux);
>>     MatSetUp(aux);
>>     MatZeroEntries(aux);
>>     MatDiagonalSet(aux, tmp, INSERT_VALUES);
>>     VecDestroy(&tmp);
>>
>>     MatAXPY(aux, -1, similarity, DIFFERENT_NONZERO_PATTERN);
>>
>> If I execute this code using only one process I get the segmentation
>> violation error:
>>
>> [0]PETSC ERROR:
>> ------------------------------------------------------------------------
>> [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]PETSCERROR: 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] MatAXPYGetPreallocation_SeqAIJ line 2562
>> src/mat/impls/aij/seq/aij.c
>> [0]PETSC ERROR: [0] MatAXPY_SeqAIJ line 2587 src/mat/impls/aij/seq/aij.c
>> [0]PETSC ERROR: [0] MatAXPY line 29 src/mat/utils/axpy.c
>> [0]PETSC ERROR: --------------------- Error Message
>> ------------------------------------
>> [0]PETSC ERROR: Signal received!
>>
>> However, if I run the same code using two processes it runs ok and gives
>> the good result.
>> Could you please tell me what am I doing wrong?
>> Grateful in advance
>>
>>
>>
>>
>
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