static char help[] = "Tests DMDAGlobalToNaturalAllCreate() using contour plotting for 2d DMDAs.\n\n";

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

int main(int argc, char **argv)
{
  PetscInt        i, j, M = 10, N = 8, m = PETSC_DECIDE, n = PETSC_DECIDE;
  PetscMPIInt     rank;
  PetscBool       flg = PETSC_FALSE;
  DM              da;
  PetscViewer     viewer;
  Vec             localall, global;
  PetscScalar     value, *vlocal;
  DMBoundaryType  bx = DM_BOUNDARY_NONE, by = DM_BOUNDARY_NONE;
  DMDAStencilType stype = DMDA_STENCIL_BOX;
  VecScatter      tolocalall, fromlocalall;
  PetscInt        start, end;

  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));
  PetscCall(PetscOptionsGetBool(NULL, NULL, "-star_stencil", &flg, NULL));
  if (flg) stype = DMDA_STENCIL_STAR;

  /* Create distributed array and get vectors */
  PetscCall(DMDACreate2d(PETSC_COMM_WORLD, bx, by, stype, M, N, m, n, 1, 1, NULL, NULL, &da));
  PetscCall(DMSetFromOptions(da));
  PetscCall(DMSetUp(da));

  PetscCall(DMCreateGlobalVector(da, &global));
  PetscCall(VecCreateSeq(PETSC_COMM_SELF, M * N, &localall));

  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  PetscCall(VecGetOwnershipRange(global, &start, &end));
  for (i = start; i < end; i++) {
    value = 5.0 * rank;
    PetscCall(VecSetValues(global, 1, &i, &value, INSERT_VALUES));
  }
  PetscCall(VecAssemblyBegin(global));
  PetscCall(VecAssemblyEnd(global));
  PetscCall(VecView(global, viewer));

  /*
     Create Scatter from global DMDA parallel vector to local vector that
   contains all entries
  */
  PetscCall(DMDAGlobalToNaturalAllCreate(da, &tolocalall));
  PetscCall(DMDANaturalAllToGlobalCreate(da, &fromlocalall));

  PetscCall(VecScatterBegin(tolocalall, global, localall, INSERT_VALUES, SCATTER_FORWARD));
  PetscCall(VecScatterEnd(tolocalall, global, localall, INSERT_VALUES, SCATTER_FORWARD));

  PetscCall(VecGetArray(localall, &vlocal));
  for (j = 0; j < N; j++) {
    for (i = 0; i < M; i++) *vlocal++ += i + j * M;
  }
  PetscCall(VecRestoreArray(localall, &vlocal));

  /* scatter back to global vector */
  PetscCall(VecScatterBegin(fromlocalall, localall, global, INSERT_VALUES, SCATTER_FORWARD));
  PetscCall(VecScatterEnd(fromlocalall, localall, global, INSERT_VALUES, SCATTER_FORWARD));

  PetscCall(VecView(global, viewer));

  /* Free memory */
  PetscCall(VecScatterDestroy(&tolocalall));
  PetscCall(VecScatterDestroy(&fromlocalall));
  PetscCall(PetscViewerDestroy(&viewer));
  PetscCall(VecDestroy(&localall));
  PetscCall(VecDestroy(&global));
  PetscCall(DMDestroy(&da));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   build:
     requires: !complex

   test:
      nsize: 3
      output_file: output/empty.out

TEST*/