Chudnovsky_Pi_me.py

# Chudnovsky algorithm for Pi
# https://en.wikipedia.org/wiki/Chudnovsky_algorithm
# Muutettu rivi 10 alkuperäisestä itse ymmärrettyyn muotoon (12*k+2)...
# lisätty aika
# Juhani Kaukoranta 23.7.2019 wikipedian avulla
from decimal import Decimal as Dec, getcontext as gc
import time
def PI(maxK, prec, disp):
    gc().prec = prec
    M, L, X, S = 1, 13591409, 1, 13591409
    for k in range(0, maxK+1):
        M = (12*k+2)*(12*k+6)*(12*k+10) * M // (k+1)**3
        L += 545140134
        X *= -262537412640768000
        S += Dec(M * L) / X
    pi = 426880 * Dec(10005).sqrt() / S
    pi = Dec(str(pi)[:disp]) # drop few digits of precision for accuracy
    print("PI(maxK={} iterations, gc().prec={}, disp={} digits) =\n{}".format(maxK, prec, disp, pi))
    return pi
digits = int(input("How many digits in Pi "))
maxK = int(digits*70/1006)+1
prec =digits+8
disp = digits+1
# defaults maxK=70,prec=1008,disp=1006 chosen to gain 1000+ digits within a few seconds
time0 = time.perf_counter()
Pi = PI(maxK,prec,digits)
time1 = time.perf_counter()
print("Aikaa kului laskentaan ja tulostukseen  ",time1-time0," sekuntia")