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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 = 2, 4, 1, 12, 4
while True:
# Next approximation
p, q, k = k*k, 2*k+1, k+1
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 = 10*(a%b), 10*(a1%b1)
d, d1 = a//b, a1//b1
def output(d):
# Use write() to avoid spaces between the digits
sys.stdout.write(str(d))
# Flush so the output is seen immediately
sys.stdout.flush()
if __name__ == "__main__":
main()
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