Or just replace
while d == d1:
with
while d == d1 and n > 0:
Gary Litvin
www.skylit.com
At 11:54 PM 12/23/2012, [email protected] wrote:
Here's an easier, pythonic way to limit the number of digits, given
the original, non-terminating pi generator:
>>> import itertools
>>> print(list( itertools.islice(pi_digits(), 10) ))
[3, 1, 4, 1, 5, 9, 2, 6, 5, 3]
David H
-----Original Message-----
From: "michel paul" <[email protected]>
Sent: Sunday, December 23, 2012 6:49pm
To: "Kirby Urner" <[email protected]>
Cc: [email protected], "[email protected]"
<[email protected]>, "michel paul" <[email protected]>
Subject: Re: [Edu-sig] generate digits of pi
I realized something. This was the original version:
def pi_digits():
k, a, b, a1, b1 = 2, 4, 1, 12, 4
while True:
p, q, k = k*k, 2*k+1, k+1
a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
d, d1 = a/b, a1/b1
while d == d1:
yield int(d)
a, a1 = 10*(a%b), 10*(a1%b1)
d, d1 = a/b, a1/b1
I forget where it came from. Like I had mentioned, I had a really
bright student awhile back who was really intrigued by this, and he
at one point edited it to produce the digits in binary. In the
original form the generator never terminates. Somewhere along the
line an edit was made to try to get it to terminate at n digits.
Probably to make calling it easy to call as in list(pi_digits(n)).
- Michel
On Sat, Dec 22, 2012 at 5:34 PM, Kirby Urner
<<mailto:[email protected]>[email protected]> wrote:
Got it, no wrong digits just not always exactly the number you asked for.
This happens often in 3.2 as well:
>>> exp = ((n,len(list(pi_digits(n)))) for n in range(10000)) #
(number asked, number got)
>>> exp2 = ((a,b) for a,b in exp if a != b) # filter on "not same"
>>> for i in range(10): print(next(exp2), end=", ")
(2, 3), (4, 5), (10, 11), (16, 17), (18, 19), (22, 23), (28, 31),
(29, 31), (30, 31), (34, 36),
Kirby
On Sat, Dec 22, 2012 at 4:40 PM,
<<mailto:[email protected]>[email protected]> wrote:
In each case I asked for only 79 digits, but got 79, 82, and 83
digits depending on whether I was using python 3.2, python 2.6, or
python 2.6 with -Qnew, respectively. The digits all seem to be
correct, but the algorithm for stopping at digit n seems to be very sensitive.
David H
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==================================
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- Richard Feynman
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"Computer science is the new mathematics."
- Dr. Christos Papadimitriou
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