static char help[] = "Tests various DM routines.\n\n";

#include <petscdm.h>
#include <petscdmda.h>

int main(int argc, char **argv)
{
  PetscMPIInt rank;
  PetscInt    M = 10, N = 8, m = PETSC_DECIDE, n = PETSC_DECIDE;
  DM          da;
  PetscViewer viewer;
  Vec         local, global;
  PetscScalar value;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));
  PetscCall(PetscViewerDrawOpen(PETSC_COMM_WORLD, 0, "", 300, 0, 300, 300, &viewer));

  /* Read options */
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-M", &M, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-N", &N, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL));

  /* Create distributed array and get vectors */
  PetscCall(DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_BOX, M, N, m, n, 1, 1, NULL, NULL, &da));
  PetscCall(DMSetFromOptions(da));
  PetscCall(DMSetUp(da));
  PetscCall(DMCreateGlobalVector(da, &global));
  PetscCall(DMCreateLocalVector(da, &local));

  value = -3.0;
  PetscCall(VecSet(global, value));
  PetscCall(DMGlobalToLocalBegin(da, global, INSERT_VALUES, local));
  PetscCall(DMGlobalToLocalEnd(da, global, INSERT_VALUES, local));

  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  value = rank + 1;
  PetscCall(VecScale(local, value));
  PetscCall(DMLocalToGlobalBegin(da, local, ADD_VALUES, global));
  PetscCall(DMLocalToGlobalEnd(da, local, ADD_VALUES, global));

  PetscCall(VecView(global, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(DMView(da, viewer));

  /* Free memory */
  PetscCall(PetscViewerDestroy(&viewer));
  PetscCall(VecDestroy(&local));
  PetscCall(VecDestroy(&global));
  PetscCall(DMDestroy(&da));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:
      nsize: 2
      args: -nox
      filter: grep -v -i Object

   test:
      suffix: cuda1
      requires: cuda
      args: -dm_vec_type cuda -nox
      filter: grep -v -i Object

   test:
      suffix: cuda2
      nsize: 2
      requires: cuda
      args: -dm_vec_type cuda -nox
      filter: grep -v -i Object

TEST*/