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Re: Challenge: optimizing isqrt

From Christian Gollwitzer <auriocus@gmx.de>
Newsgroups comp.lang.python
Subject Re: Challenge: optimizing isqrt
Date 2014-11-01 09:38 +0100
Organization A noiseless patient Spider
Message-ID <m3265d$o6q$1@dont-email.me> (permalink)
References <54543787$0$13005$c3e8da3$5496439d@news.astraweb.com> <m3241t$ihv$1@dont-email.me> <mailman.15379.1414830070.18130.python-list@python.org> <m325dt$lsl$1@dont-email.me> <mailman.15380.1414830791.18130.python-list@python.org>

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Am 01.11.14 09:33, schrieb Chris Angelico:
> On Sat, Nov 1, 2014 at 7:25 PM, Christian Gollwitzer <auriocus@gmx.de> wrote:
>>> Part of the point of that algorithm is that it never uses FP, and is
>>> therefore not limited by FP restrictions.
>>
>>
>> which are???
>
> Most notably, the inability to represent every integer beyond 2**53,
> and the inability to represent any integer beyond 2**1024. This
> algorithm should work fine with any positive integer.
>
  OK so you did not bother to look at my proposed alternative 
implementation. If I understood Steven correctly, he wanted to speed up 
the original isqrt algorithm by using FP when this is possible. I have 
shown how to do it for n<2**1022 (maybe 2**1024, I'm to lean to check 
it). I admit that there is some microoptimizatio left, e.g. the first 
division is done twice, the comparison should be bits>1022, not n>2*1022 
etc.

	Christian

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Thread

Challenge: optimizing isqrt Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-01 12:29 +1100
  Re: Challenge: optimizing isqrt Chris Angelico <rosuav@gmail.com> - 2014-11-01 13:12 +1100
  Re: Challenge: optimizing isqrt Christian Gollwitzer <auriocus@gmx.de> - 2014-11-01 09:02 +0100
    Re: Challenge: optimizing isqrt Christian Gollwitzer <auriocus@gmx.de> - 2014-11-01 09:09 +0100
    Re: Challenge: optimizing isqrt Chris Angelico <rosuav@gmail.com> - 2014-11-01 19:13 +1100
      Re: Challenge: optimizing isqrt Christian Gollwitzer <auriocus@gmx.de> - 2014-11-01 09:25 +0100
        Re: Challenge: optimizing isqrt Chris Angelico <rosuav@gmail.com> - 2014-11-01 19:33 +1100
          Re: Challenge: optimizing isqrt Christian Gollwitzer <auriocus@gmx.de> - 2014-11-01 09:38 +0100
            Re: Challenge: optimizing isqrt Chris Angelico <rosuav@gmail.com> - 2014-11-01 19:45 +1100
  Re: Challenge: optimizing isqrt Akira Li <4kir4.1i@gmail.com> - 2014-11-01 12:12 +0300
  Re: Challenge: optimizing isqrt Serhiy Storchaka <storchaka@gmail.com> - 2014-11-20 20:00 +0200
  Re: Challenge: optimizing isqrt Stephen Tucker <stephen_tucker@sil.org> - 2014-11-21 08:15 +0000
  Re: Challenge: optimizing isqrt Dave Angel <davea@davea.name> - 2014-11-23 10:43 -0500
  Re: Challenge: optimizing isqrt Serhiy Storchaka <storchaka@gmail.com> - 2014-11-25 21:31 +0200
  Re: Challenge: optimizing isqrt Dave Angel <davea@davea.name> - 2014-11-25 19:46 -0500
  Re: Challenge: optimizing isqrt Stephen Tucker <stephen_tucker@sil.org> - 2014-11-26 07:57 +0000
    Re: Challenge: optimizing isqrt Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-26 21:25 +1100
  Re: Challenge: optimizing isqrt Serhiy Storchaka <storchaka@gmail.com> - 2014-11-26 18:24 +0200

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