Now we are ready to look at the entire script for our demo problem, the scalar product:
from mpi4py import MPI
import numpy as np
comm = MPI.COMM_WORLD
rank = comm.Get_rank()
nprocessors = comm.Get_size()
import splitarray as spa
if rank == 0:
# Here we generate data for the example
n = 150
u = 0.1*np.arange(n)
v = - u
u_split = spa.split_array(u, nprocessors)
v_split = spa.split_array(v, nprocessors)
else:
# On all processor we need variables with these names,
# otherwise we would get an Exception "Variable not defined" in
# the scatter command below
u_split = None
v_split = None
# These commands run now on all processors
u_split = comm.scatter(u_split, root=0) # the data is portion wise
# distributed from root
v_split = comm.scatter(v_split, root=0)
# Each processor computes its part of the scalar product
partial_dot = u_split@v_split
# Each processor reports its result...
