view Demo/scripts/pi.py @ 58925:eecf1bef052d 2.6

Merged revisions 78207 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r78207 | ezio.melotti | 2010-02-17 01:26:09 +0200 (Wed, 17 Feb 2010) | 1 line #7930: fix stripid ........
author Ezio Melotti <ezio.melotti@gmail.com>
date Tue, 16 Feb 2010 23:29:44 +0000
parents 41524f9e2a2f
children 33b041350034
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#! /usr/bin/env python

# Print digits of pi forever.
#
# The algorithm, using Python's 'long' integers ("bignums"), works
# with continued fractions, and was conceived by Lambert Meertens.
#
# See also the ABC Programmer's Handbook, by Geurts, Meertens & Pemberton,
# published by Prentice-Hall (UK) Ltd., 1990.

import sys

def main():
    k, a, b, a1, b1 = 2L, 4L, 1L, 12L, 4L
    while 1:
        # Next approximation
        p, q, k = k*k, 2L*k+1L, k+1L
        a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
        # Print common digits
        d, d1 = a//b, a1//b1
        while d == d1:
            output(d)
            a, a1 = 10L*(a%b), 10L*(a1%b1)
            d, d1 = a//b, a1//b1

def output(d):
    # Use write() to avoid spaces between the digits
    # Use str() to avoid the 'L'
    sys.stdout.write(str(d))
    # Flush so the output is seen immediately
    sys.stdout.flush()

if __name__ == "__main__":
    main()