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# -*- Mode: Python -*-
# [reworking of the version in Python-1.5.1/Demo/scripts/pi.py]
# 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 string
StopException = "Stop!"
def go (file):
try:
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:
if file.write (str(int(d))):
raise StopException
a, a1 = 10L*(a%b), 10L*(a1%b1)
d, d1 = a/b, a1/b1
except StopException:
return
class line_writer:
"partition the endless line into 80-character ones"
def __init__ (self, file, digit_limit=10000):
self.file = file
self.buffer = ''
self.count = 0
self.digit_limit = digit_limit
def write (self, data):
self.buffer = self.buffer + data
if len(self.buffer) > 80:
line, self.buffer = self.buffer[:80], self.buffer[80:]
self.file.write (line+'\r\n')
self.count = self.count + 80
if self.count > self.digit_limit:
return 1
else:
return 0
def main (env, stdin, stdout):
parts = string.split (env['REQUEST_URI'], '/')
if len(parts) >= 3:
ndigits = string.atoi (parts[2])
else:
ndigits = 5000
stdout.write ('Content-Type: text/plain\r\n\r\n')
go (line_writer (stdout, ndigits))
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