pi

ramanujan.py

# Ramanujan's PI algorithm, per Think Python
#
# >>> execfile("C:/[snip]/Desktop/ramanujan.py")
# >>> rpi()

import math

def rpi ():
   k = 0
   estimate = 0.0
   start = True

   while start == True or term >= 1e-15:
      start = False
      term = innerTerm(k) * 2 * math.sqrt(2) / 9801
      estimate += term
      k += 1
   
   return 1/estimate

def innerTerm(k):
   a = math.factorial(4*k) * (1103+26390*k) 
   b = (math.factorial(k)**4) * (396**(4*k))
   return a / b