static char help[] = "Testing MatCreateMPIAIJSumSeqAIJ().\n\n";

#include <petscmat.h>

int main(int argc, char **argv)
{
  Mat         A, B;
  MatScalar   a[1], alpha;
  PetscMPIInt size, rank;
  PetscInt    m, n, i, col, prid;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));
  PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  prid = size;
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-prid", &prid, NULL));

  m = n = 10 * size;
  PetscCall(MatCreate(PETSC_COMM_SELF, &A));
  PetscCall(MatSetSizes(A, PETSC_DETERMINE, PETSC_DETERMINE, m, n));
  PetscCall(MatSetType(A, MATSEQAIJ));
  PetscCall(MatSetUp(A));

  a[0] = rank + 1;
  for (i = 0; i < m - rank; i++) {
    col = i + rank;
    PetscCall(MatSetValues(A, 1, &i, 1, &col, a, INSERT_VALUES));
  }
  PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
  PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));

  if (rank == prid) {
    PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] A: \n", rank));
    PetscCall(MatView(A, PETSC_VIEWER_STDOUT_SELF));
  }

  /* Test MatCreateMPIAIJSumSeqAIJ */
  PetscCall(MatCreateMPIAIJSumSeqAIJ(PETSC_COMM_WORLD, A, PETSC_DECIDE, PETSC_DECIDE, MAT_INITIAL_MATRIX, &B));

  /* Test MAT_REUSE_MATRIX */
  alpha = 0.1;
  for (i = 0; i < 3; i++) {
    PetscCall(MatScale(A, alpha));
    PetscCall(MatCreateMPIAIJSumSeqAIJ(PETSC_COMM_WORLD, A, PETSC_DECIDE, PETSC_DECIDE, MAT_REUSE_MATRIX, &B));
  }
  PetscCall(MatView(B, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(MatDestroy(&B));
  PetscCall(MatDestroy(&A));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:
      nsize: 3
      filter: grep -v " MPI process"

   test:
      suffix: 2
      filter: grep -v " MPI process"

TEST*/