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1801
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1 #! /usr/local/bin/python
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2 # Print digits of pi forever.
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3 #
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4 # The algorithm, using Python's 'long' integers ("bignums"), works
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5 # with continued fractions, and was conceived by Lambert Meertens.
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6 #
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7 # See also the ABC Programmer's Handbook, by Geurts, Meertens & Pemberton,
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8 # published by Prentice-Hall (UK) Ltd., 1990.
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9
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10 import sys
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11 from mpz import mpz
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12
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13 def main():
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14 mpzone, mpztwo, mpzten = mpz(1), mpz(2), mpz(10)
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15 k, a, b, a1, b1 = mpz(2), mpz(4), mpz(1), mpz(12), mpz(4)
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16 while 1:
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17 # Next approximation
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18 p, q, k = k*k, mpztwo*k+mpzone, k+mpzone
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19 a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
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20 # Print common digits
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21 d, d1 = a/b, a1/b1
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22 while d == d1:
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23 output(d)
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24 a, a1 = mpzten*(a%b), mpzten*(a1%b1)
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25 d, d1 = a/b, a1/b1
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26
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27 def output(d):
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28 # Use write() to avoid spaces between the digits
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29 # Use int(d) to avoid a trailing L after each digit
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30 sys.stdout.write(`int(d)`)
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31 # Flush so the output is seen immediately
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32 sys.stdout.flush()
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33
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34 main()
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