[petsc-users] MatSetValues() for MATMPICUSP

[Jed Brown]

On Sat, Feb 11, 2012 at 10:58, recrusader <recrusader at gmail.com> wrote:

>     "    ierr = MatCreateMPIAIJ (libMesh::COMM_WORLD,
>
>   m_local, n_local,
>                                 m_global, n_global,
>                                 PETSC_NULL, (int*) &n_nz[0],
>                                 PETSC_NULL, (int*) &n_oz[0], &_mat);
>              CHKERRABORT(libMesh::COMM_WORLD,ierr);
>
>       MatSetOption(_mat,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE); //by
> Yujie
>       std::cout<<"MatSetOption"<<std::endl;"
>
> I run the same codes in CPU and GPU modes (the same parameters except that
> GPU uses '-vec_type mpicusp -mat_type mpiaijcusp'). I can find
> "MatSetOption" output from both the modes. Does that mean that the codes
> set the options for both the modes?
>

Libmesh is calling MatSetFromOptions() after MatCreateMPIAIJ() which means
the preallocation information will be lost if the type is changed. The code
should be written differently

  ierr = MatCreate(comm,A);CHKERRQ(ierr);
  ierr = MatSetSizes(*A,m,n,M,N);CHKERRQ(ierr);
  ierr = MPI_Comm_size(comm,&size);CHKERRQ(ierr);
  ierr = MatSetType(*A,MATAIJ);CHKERRQ(ierr);
  ierr = MatSetOptionsPrefix(*A,optional_prefix);CHKERRQ(ierr);
  ierr = MatSetFromOptions(*A);CHKERRQ(ierr);
  ierr = MatMPIAIJSetPreallocation(*A,d_nz,d_nnz,o_nz,o_nnz);CHKERRQ(ierr);
  ierr = MatSeqAIJSetPreallocation(*A,d_nz,d_nnz);CHKERRQ(ierr);

I can talk to the libmesh developers about making this change.
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