Path: csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!news.tele.dk!feed118.news.tele.dk!news.tele.dk!small.news.tele.dk!newsfeed.xs4all.nl!newsfeed5.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.002 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'terry': 0.07; 'python': 0.08; 'conditional': 0.09; 'correct.': 0.09; 'finishes': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:80.91.229.12': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'received:lo.gmane.org': 0.09; 'pm,': 0.10; '>>>': 0.12; 'wrote:': 0.14; 'reedy': 0.16; 'sane': 0.16; 'thinking.': 0.16; 'what?': 0.16; 'algorithm': 0.16; 'great.': 0.16; 'seconds': 0.16; 'writes:': 0.19; 'jan': 0.20; 'header:In- Reply-To:1': 0.21; 'algorithms': 0.23; 'algorithms.': 0.23; 'statement': 0.26; 'paul': 0.28; 'problem': 0.28; 'least': 0.30; 'subject:How': 0.30; 'print': 0.31; 'apply': 0.32; 'header:X -Complaints-To:1': 0.32; 'to:addr:python-list': 0.33; 'break': 0.33; 'header:User-Agent:1': 0.35; 'languages': 0.35; 'idea': 0.36; 'problems': 0.36; 'takes': 0.37; 'something': 0.37; 'think': 0.38; 'received:org': 0.38; 'subject:can': 0.38; 'subject:: ': 0.38; 'header:Mime-Version:1': 0.39; 'to:addr:python.org': 0.39; 'plain': 0.40; 'really': 0.40; 'more': 0.60; 'best': 0.60; 'powered': 0.62; 'limit': 0.65; 'minutes': 0.67; 'contrary': 0.67; 'yourself': 0.68; 'here.': 0.69; 'obtained': 0.73; 'low': 0.73; 'subject:over': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: How can I speed up a script that iterates over a large range (600 billion)? Date: Wed, 22 Jun 2011 00:18:42 -0400 References: <7x7h8eivkf.fsf@ruckus.brouhaha.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: rain.gmane.org User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.17) Gecko/20110414 Lightning/1.0b2 Thunderbird/3.1.10 In-Reply-To: <7x7h8eivkf.fsf@ruckus.brouhaha.com> X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 31 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1308716334 news.xs4all.nl 49038 [::ffff:82.94.164.166]:35002 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:8180 On 6/21/2011 8:00 PM, Paul Rubin wrote: > Terry Reedy writes: >>> efficient implementation will allow a solution to be obtained on a >>> modestly powered computer in less than one minute." >> If something really takes a minute in C, >> allow yourself at least 10 minutes or even more with plain CPython. > > No. No what? My conditional statement is correct. It turns out not to apply here. Great. > The idea of the Euler problems is to think up sane algorithms to > solve them, not micro-optimize or use low level languages on crappy > algorithms. > > n=600851475143 > for d in xrange(2,n): > if d*d> n: break > while n%d == 0: n //= d > print n > > finishes on my laptop with no noticable pause. If the best C program for a problem takes 10 seconds or more, then applying the same 1 minute limit to Python is insane, and contrary to the promotion of good algorithm thinking. -- Terry Jan Reedy