xref: /petsc/src/dm/tests/ex38.c (revision 732aec7a18f2199fb53bb9a2f3aef439a834ce31)

static char help[] = "Tests DMGlobalToLocal() for 3d DA with stencil width of 2.\n\n";

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

int main(int argc, char **argv)
{
  PetscInt        N = 3, M = 2, P = 4, dof = 1, rstart, rend, i;
  PetscInt        stencil_width = 2;
  PetscMPIInt     rank;
  DMBoundaryType  bx = DM_BOUNDARY_NONE, by = DM_BOUNDARY_NONE, bz = DM_BOUNDARY_NONE;
  DMDAStencilType stencil_type = DMDA_STENCIL_STAR;
  DM              da;
  Vec             global, local;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-M", &M, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-N", &N, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-P", &P, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-dof", &dof, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-stencil_width", &stencil_width, NULL));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-stencil_type", (PetscInt *)&stencil_type, NULL));

  PetscCall(DMDACreate3d(PETSC_COMM_WORLD, bx, by, bz, stencil_type, M, N, P, PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE, dof, stencil_width, 0, 0, 0, &da));
  PetscCall(DMSetFromOptions(da));
  PetscCall(DMSetUp(da));
  PetscCall(DMCreateGlobalVector(da, &global));
  PetscCall(VecGetOwnershipRange(global, &rstart, &rend));
  for (i = rstart; i < rend; i++) PetscCall(VecSetValue(global, i, (PetscReal)(i + 100 * rank), INSERT_VALUES));
  PetscCall(VecAssemblyBegin(global));
  PetscCall(VecAssemblyEnd(global));
  PetscCall(DMCreateLocalVector(da, &local));
  PetscCall(VecSet(local, -1));
  PetscCall(DMGlobalToLocalBegin(da, global, INSERT_VALUES, local));
  PetscCall(DMGlobalToLocalEnd(da, global, INSERT_VALUES, local));
  if (rank == 0) PetscCall(VecView(local, 0));
  PetscCall(DMDestroy(&da));
  PetscCall(VecDestroy(&local));
  PetscCall(VecDestroy(&global));
  PetscCall(PetscFinalize());
  return 0;
}