mpi.py

from decimal import Decimal, getcontext
from time import clock
from math import pi

from multiprocessing import Pool, cpu_count

import sys

if len(sys.argv) < 2:
    n = 10000
else:
    try:
        n = int(sys.argv[1])
    except:
        print("Fehler: Argument ist keine gültige Zahl.", file=sys.stderr)
        sys.exit( -1)

f = lambda x: 7.5 * x **-.5

getcontext().prec=n

le = 0

#s = [Decimal(1)/Decimal(3) for i in range(n)]

e = Decimal(0)


def pi_p(q):
    v,b, pb = q
    s = [Decimal(1)/Decimal(3) for i in range(b-v)] 
    #n = b-v
    l = clock()
    for k in range(v, b):
        #print(k)
        s[v-k] = (1/Decimal(16)**k *
          (Decimal(4)/(8*k+1) -
           Decimal(2)/(8*k+4) -
           Decimal(1)/(8*k+5) -
           Decimal(1)/(8*k+6)))
        if pb:
            if (not (k % int(n/100/25+1))) or k == 99:
                p = round(k/n*100, 1)
                print(" ["+"#"*int(p//2)+" "*(50-int(p//2))+"] "+str(p)+"%", end=" ")
                if k < 99:
                    print(end="\r")
                    continue
                elif k == 99:
                    g = sum(f(i) for i in range(100,n+1)) / (n-100)
                    vk = (20/(clock()-l)) * g
                eta = int((n-k)/vk)
                m, se = divmod(eta, 60)
                if not m:
                    h = 0
                else:
                    h, m = divmod(m, 60)
                print("ETA: %d:%02d:%02d" % (h, m, se), end="\r")
    return sum(s)

#pi_p

if __name__ == "__main__":
    ls = clock()
    c = cpu_count()
    args = []
    p, r = divmod(n, c)
    for i in range(c):
        arg = [i*n, (i+1)*n ,i==0]
        args.append(arg)
    with Pool() as p:
        mpi = sum(p.map(pi_p, args))
    assert round(pi, 4) == float(round(mpi, 4))    

    print()
    print("GS:",clock()-ls)