#!/usr/bin/python
import numpy
from mpi4py import MPI
import time
comm = MPI.COMM_WORLD
rank = comm.Get_rank()
size = comm.Get_size()
a = 1
b = 1000000
perrank = b//size
summ = numpy.zeros(1)
comm.Barrier()
start_time = time.time()
temp = 0
for i in range(a + rank*perrank, a + (rank+1)*perrank):
temp = temp + i
summ[0] = temp
if rank == 0:
total = numpy.zeros(1)
else:
total = None
comm.Barrier()
#collect the partial results and add to the total sum
comm.Reduce(summ, total, op=MPI.SUM, root=0)
stop_time = time.time()
if rank == 0:
#add the rest numbers to 1 000 000
for i in range(a + (size)*perrank, b+1):
total[0] = total[0] + i
print ("The sum of numbers from 1 to 1 000 000: ", int(total[0]))
print ("time spent with ", size, " threads in milliseconds")
print ("-----", int((time.time()-start_time)*1000), "-----")
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