Update of cpi-cco.py from mpi4py to allow parameterisation of the iteration count at the command line, and to remove looping.
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#!/usr/bin/env python | |
""" | |
Parallel PI computation using Collective Communication Operations (CCO) | |
within Python objects exposing memory buffers (requires NumPy). | |
usage:: | |
$ mpiexec -n <nprocs> python cpi-buf.py | |
""" | |
from mpi4py import MPI | |
from math import pi as PI | |
from numpy import array | |
import argparse | |
parser = argparse.ArgumentParser() | |
parser.add_argument('iterations', metavar='N', type=int, nargs='?') | |
args = parser.parse_args() | |
def get_n(): | |
if args.iterations: | |
return args.iterations | |
prompt = "Enter the number of intervals: (0 quits) " | |
try: | |
n = int(input(prompt)) | |
if n < 0: n = 0 | |
except: | |
n = 0 | |
return n | |
def comp_pi(n, myrank=0, nprocs=1): | |
h = 1.0 / n | |
s = 0.0 | |
for i in range(myrank + 1, n + 1, nprocs): | |
x = h * (i - 0.5) | |
s += 4.0 / (1.0 + x**2) | |
return s * h | |
def prn_pi(pi, PI): | |
message = "pi is approximately %.16f, error is %.16f" | |
print (message % (pi, abs(pi - PI))) | |
comm = MPI.COMM_WORLD | |
nprocs = comm.Get_size() | |
myrank = comm.Get_rank() | |
n = array(0, dtype=int) | |
pi = array(0, dtype=float) | |
mypi = array(0, dtype=float) | |
if myrank == 0: | |
_n = get_n() | |
n.fill(_n) | |
comm.Bcast([n, MPI.INT], root=0) | |
_mypi = comp_pi(n, myrank, nprocs) | |
mypi.fill(_mypi) | |
comm.Reduce([mypi, MPI.DOUBLE], [pi, MPI.DOUBLE], | |
op=MPI.SUM, root=0) | |
if myrank == 0: | |
prn_pi(pi, PI) | |
# ======================= | |
# LICENSE: MPI for Python | |
# ======================= | |
# | |
# :Author: Lisandro Dalcin | |
# :Contact: dalcinl@gmail.com | |
# | |
# | |
# Copyright (c) 2014, Lisandro Dalcin. | |
# All rights reserved. | |
# | |
# Redistribution and use in source and binary forms, with or without | |
# modification, are permitted provided that the following conditions | |
# are met: | |
# | |
# * Redistributions of source code must retain the above copyright | |
# notice, this list of conditions and the following disclaimer. | |
# | |
# * Redistributions in binary form must reproduce the above copyright | |
# notice, this list of conditions and the following disclaimer in the | |
# documentation and/or other materials provided with the distribution. | |
# | |
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS | |
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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