Using set_local with mpi

General
1

Any insights on this script not working with mpich are appreciated.

from dolfin import *
from mpi4py import MPI as pyMPI

nx = 4; ny = 4; nz=4
mesh_m = BoxMesh(Point(0, 0, 0), Point(1, 1, 1), nx, ny, nz)

#comm_me = mesh_m.mpi_comm()

V_n = VectorFunctionSpace(mesh_m, "CG", 2)
a_n = Function(V_n)

dim = mesh_m.geometry().dim()
u_coord = V_n.tabulate_dof_coordinates().reshape(-1, dim)

b_n = u_coord[::3]
b_n = b_n.ravel()

a_n.vector().set_local(b_n)

pvd_real = File("box_coord.pvd")
pvd_real << a_n