RiemannZeta3_rapid.py

# Calculates Riemann's Zeta(3)
# which is also Apery's constant
# using rapid algorith
# Juhani Kaukoranta 24.6.2018

from decimal import *
import math
import time


def binomial(n,k):
    a = math.factorial(n)//(math.factorial(n-k)*math.factorial(k))
    return(a)

def Zeta3(precision):
    getcontext().prec=precision
    r = Decimal(0)
    sgn = 1
    for n in range(1,2*precision):
        r = r+sgn*Decimal(1)/(n*n*n*binomial(2*n,n))
        sgn = -1*sgn
    return(5*r/2)
precision = int(input("How many numbers precision, f.eq 100 "))
time0 = time.clock()
print("Apery constant , Zeta(3) = ",Zeta3(precision))
time1 = time.clock()
print("calculation time ",time1-time0," seconds")