| Guido van Rossum | f06ee5f | 1996-11-27 19:52:01 +0000 | [diff] [blame] | 1 | #! /usr/bin/env python |
| Guido van Rossum | 4040ed0 | 1994-08-19 15:09:02 +0000 | [diff] [blame] | 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() |