Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed3.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <python-python-list@m.gmane.org>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.033
X-Spam-Evidence: '*H*': 0.93; '*S*': 0.00; 'lines,': 0.07; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; '(about': 0.16; 'interest,': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'thanks,': 0.17; 'slightly': 0.19; 'header:User-Agent:1': 0.23; 'looks': 0.24; 'header:X -Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'too.': 0.31; 'faster,': 0.31; 'but': 0.35; 'there': 0.35; 'skip:\xd0 10': 0.36; 'to:addr:python-list': 0.38; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'matter': 0.61; 'total': 0.65; 'received:46': 0.66; 'worth': 0.66; '8bit%:94': 0.72; '10%': 0.74; '8bit%:43': 0.74; 'measurable': 0.84
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Serhiy Storchaka <storchaka@gmail.com>
Subject: Re: Challenge: optimizing isqrt
Date: Tue, 25 Nov 2014 21:31:43 +0200
References: <54543787$0$13005$c3e8da3$5496439d@news.astraweb.com> <m4la9e$5hl$1@ger.gmane.org> <CAP=-cKWj5yeL34GG5ay4v-V9i6nuTgF3VvmC8=PDOYruwp8q5Q@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
X-Gmane-NNTP-Posting-Host: 46.211.144.47
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.0
In-Reply-To: <CAP=-cKWj5yeL34GG5ay4v-V9i6nuTgF3VvmC8=PDOYruwp8q5Q@mail.gmail.com>
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list/>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.16293.1416944005.18130.python-list@python.org>
Lines: 18
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1416944005 news.xs4all.nl 2904 [2001:888:2000:d::a6]:53222
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:81525

п'ятниця, 21-лис-2014 08:15:57 ви написали:
> This looks very good indeed. As a matter of interest, is there any
> particular reason you have used 2*b instead of b+b? Might b+b be faster
> than b*2?

Yes, it is slightly faster, but the effect is indiscernible in total 
time. But
there is not harm to use b+b.

> Also, in various lines, you use //2. Would >>1 be quicker? On reflection,
> perhaps you have had to use //2 because >>1 cannot be used in those
> situations.

I thought this effect would be insignificant too. But actually it is 
measurable
(about 10% for some input). Thanks, this optimization is worth to be 
applied.