Demo/scripts/mpzpi.py

   1 #! /usr/local/bin/python
   2 # Print digits of pi forever.
   3 #
   4 # The algorithm, using Python's 'long' integers ("bignums"), works
   5 # with continued fractions, and was conceived by Lambert Meertens.
   6 #
   7 # See also the ABC Programmer's Handbook, by Geurts, Meertens & Pemberton,
   8 # published by Prentice-Hall (UK) Ltd., 1990.
   9
  10 import sys
  11 from mpz import mpz
  12
  13 def main():
  14         mpzone, mpztwo, mpzten = mpz(1), mpz(2), mpz(10)
  15         k, a, b, a1, b1 = mpz(2), mpz(4), mpz(1), mpz(12), mpz(4)
  16         while 1:
  17                 # Next approximation
  18                 p, q, k = k*k, mpztwo*k+mpzone, k+mpzone
  19                 a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
  20                 # Print common digits
  21                 d, d1 = a/b, a1/b1
  22                 while d == d1:
  23                         output(d)
  24                         a, a1 = mpzten*(a%b), mpzten*(a1%b1)
  25                         d, d1 = a/b, a1/b1
  26
  27 def output(d):
  28         # Use write() to avoid spaces between the digits
  29         # Use int(d) to avoid a trailing L after each digit
  30         sys.stdout.write(`int(d)`)
  31         # Flush so the output is seen immediately
  32         sys.stdout.flush()
  33
  34 main()