Klaus,
You would really benefit by upgrading to PETSc 3.5.3, we added much faster
symbolic MatAXPY() for the DIFFERENT_NONZERO_STRUCTURE flag. Plus it is much
easier for us to support the newest version.
Barry
> On Mar 27, 2015, at 9:48 AM, Klaus Kaiser <[email protected]> wrote:
>
> Hallo,
>
> I have a strange behavior in my code concerning the function MatAXPY. I
> create 3 different Matrices
>
> ierr = MatCreateBAIJ(PETSC_COMM_WORLD, block_size, local_size, local_size,
> system_size, system_size, 0, d_nnz, 0, o_nnz,&A);
> ierr = MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_TRUE);
> ierr = MatSetOption(A,MAT_KEEP_NONZERO_PATTERN,PETSC_TRUE);
> ierr = MatSetOption(A,MAT_IGNORE_OFF_PROC_ENTRIES,PETSC_TRUE);
>
> ierr = MatCreateBAIJ(PETSC_COMM_WORLD, block_size, local_size, local_size,
> system_size, system_size, 0, d_nnz, 0, o_nnz,&At);
> ierr = MatSetOption(At,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_TRUE);
> ierr = MatSetOption(At,MAT_KEEP_NONZERO_PATTERN,PETSC_TRUE);
> ierr = MatSetOption(At,MAT_IGNORE_OFF_PROC_ENTRIES,PETSC_TRUE);
>
> ierr = MatCreateBAIJ(PETSC_COMM_WORLD, block_size, local_size, local_size,
> system_size, system_size, 0, d_nnz, 0, o_nnz,&Ah);
> ierr = MatSetOption(Ah,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_TRUE);
> ierr = MatSetOption(Ah,MAT_KEEP_NONZERO_PATTERN,PETSC_TRUE);
> ierr = MatSetOption(Ah,MAT_IGNORE_OFF_PROC_ENTRIES,PETSC_TRUE);
>
> and want to sum these three matrixes with different factors. First I fill the
> Matrix A with some values, and duplicate the structure of A to the other two
> matrices:
>
> MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
> MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
> MatDuplicate(A,MAT_DO_NOT_COPY_VALUES,&Ah);
> MatDuplicate(A,MAT_DO_NOT_COPY_VALUES,&At);
> MatAssemblyBegin(Ah,MAT_FINAL_ASSEMBLY);
> MatAssemblyEnd(Ah,MAT_FINAL_ASSEMBLY);
> MatAssemblyBegin(At,MAT_FINAL_ASSEMBLY);
> MatAssemblyEnd(At,MAT_FINAL_ASSEMBLY);
>
> After this I fill the matrices At and Ah with some other values, which are
> not beside the non zero structure (I also tried with just copying the Matrix
> A). Now after another MatAssembly I want to add these Matrices in the form
> A+c*(Ah+d*At):
>
> MatAXPY(Ah,c,At,SAME_NONZERO_PATTERN);
> MatAXPY(A,d,Ah,SAME_NONZERO_PATTERN);
>
> When I run the method with mpi and one core everything works fine. Starting
> the same method with more cores, the sum of the matrices fails. It seems like
> some values are added correctly and many values are missed. Using
> DIFFERENT_NONZERO_STRUCTURE leads to the right behavior in the multi-core
> case, but is very slow. I checked with a viewer if all matrices have the same
> nonzero structure and this is the case.
>
> Does anyone know why this fails, or do I have made any wrong thoughts?
>
> I'm corrently working with a petsc version (Petsc Release Version 3.3.0,
> Patch 5, Sat Dec 1 15:10:41 CST 2012), I looked into the changelogs up to
> the current version and did not find any note about MatAXPY or MatAYPX.
>
>
> Best and Thanks a lot for your help
>
> Klaus
>
