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Groups > comp.lang.python > #79430
| Date | 2014-10-22 05:43 -0500 |
|---|---|
| From | Tim Chase <python.list@tim.thechases.com> |
| Subject | Re: (-1)**1000 |
| References | <54476a77$0$21664$426a74cc@news.free.fr> <mailman.15058.1413968065.18130.python-list@python.org> <5447786d$0$12750$426a74cc@news.free.fr> <m280ur$aho$1@ger.gmane.org> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.15066.1413975559.18130.python-list@python.org> (permalink) |
On 2014-10-22 12:29, Peter Otten wrote: > That looks like log(a) while a parity check takes constant time: > > $ python3 -m timeit -s 'a = 10**10' 'a & 1' > 10000000 loops, best of 3: 0.124 usec per loop > $ python3 -m timeit -s 'a = 10**100' 'a & 1' > 10000000 loops, best of 3: 0.124 usec per loop > $ python3 -m timeit -s 'a = 10**1000' 'a & 1' > 10000000 loops, best of 3: 0.122 usec per loop Just for the record, this is a one-bit even/odd check (which is useful & fast in this sign-of-large-exponent case), not a parity check (which typically counts the number of "1" bits, adds the parity bit, and asserts the result is even) -tkc
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(-1)**1000 "ast" <nomail@invalid.com> - 2014-10-22 10:27 +0200
Re: (-1)**1000 Chris Angelico <rosuav@gmail.com> - 2014-10-22 19:54 +1100
Re: (-1)**1000 "ast" <nomail@invalid.com> - 2014-10-22 11:27 +0200
Re: (-1)**1000 Peter Otten <__peter__@web.de> - 2014-10-22 12:29 +0200
Re: (-1)**1000 Michiel Overtoom <motoom@xs4all.nl> - 2014-10-22 12:38 +0200
Re: (-1)**1000 Tim Chase <python.list@tim.thechases.com> - 2014-10-22 05:43 -0500
Re: (-1)**1000 Peter Otten <__peter__@web.de> - 2014-10-22 13:02 +0200
Re: (-1)**1000 Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-22 08:23 -0600
Re: (-1)**1000 Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-22 08:29 -0600
Re: (-1)**1000 Ned Batchelder <ned@nedbatchelder.com> - 2014-10-22 11:01 -0400
Re: (-1)**1000 wxjmfauth@gmail.com - 2014-10-22 04:35 -0700
Re: (-1)**1000 Peter Otten <__peter__@web.de> - 2014-10-22 11:13 +0200
Re: (-1)**1000 Terry Reedy <tjreedy@udel.edu> - 2014-10-22 13:15 -0400
Re: (-1)**1000 Dave Angel <davea@davea.name> - 2014-10-24 13:57 -0400
Re: (-1)**1000 Tony the Tiger <tony@tiger.invalid> - 2014-10-26 20:07 +0000
Re: (-1)**1000 Ned Batchelder <ned@nedbatchelder.com> - 2014-10-26 16:45 -0400
Re: (-1)**1000 Stefan Behnel <stefan_ml@behnel.de> - 2014-10-29 20:31 +0100
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