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Guido van Rossumf06ee5f1996-11-27 19:52:01 +00001#! /usr/bin/env python
Guido van Rossum4040ed01994-08-19 15:09:02 +00002# 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
10import sys
11from mpz import mpz
12
13def 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
27def 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
34main()