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Re: (-1)**1000

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Date Wed, 22 Oct 2014 05:43:02 -0500
From Tim Chase <python.list@tim.thechases.com>
To Peter Otten <__peter__@web.de>
Subject Re: (-1)**1000
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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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Thread

(-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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