#include "petsc.h"

int
main(int argc, char * argv[])
{
    MPI_Comm comm;
    PetscReal lower[2] = { 0, 0 };
    PetscReal upper[2] = { 1, 1 };
    PetscInt faces[2] = { 1, 1 };
    DMBoundaryType periodicity[2] = { DM_BOUNDARY_GHOSTED, DM_BOUNDARY_GHOSTED };
    DM dm;
    PetscInt nc[1] = { 1 };
    PetscInt n_dofs[3] = { 1, 0, 0 };
    PetscSection s;
    Vec x;
    PetscViewer viewer;

    PetscInitialize(&argc, &argv, NULL, NULL);
    comm = PETSC_COMM_WORLD;

    DMPlexCreateBoxMesh(comm, 2, PETSC_FALSE, faces, lower, upper, periodicity, PETSC_TRUE, &dm);
    DMSetUp(dm);

    DMSetNumFields(dm, 1);
    DMPlexCreateSection(dm, NULL, nc, n_dofs, 0, NULL, NULL, NULL, NULL, &s);
    DMSetLocalSection(dm, s);

    DMCreateGlobalVector(dm, &x);
    VecSetValue(x, 0, 2, INSERT_VALUES);
    VecSetValue(x, 1, 3, INSERT_VALUES);
    VecSetValue(x, 2, 5, INSERT_VALUES);
    VecSetValue(x, 3, 8, INSERT_VALUES);

    PetscViewerCreate(comm, &viewer);
    PetscViewerSetType(viewer, PETSCVIEWEREXODUSII);
    PetscViewerFileSetMode(viewer, FILE_MODE_WRITE);
    PetscViewerFileSetName(viewer, "out.exo");

    DMView(dm, viewer);
    VecView(x, viewer);

    PetscViewerDestroy(&viewer);

    PetscFinalize();
}