Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed6.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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'implements': 0.05; 'commonly': 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; 'subject:python': 0.11; 'binary': 0.13; '"0"': 0.16; 'addition.': 0.16; 'bieber': 0.16; 'declaimed': 0.16; 'email addr:ix.netcom.com': 0.16; 'email name:wlfraed': 0.16; 'from:addr:ix.netcom.com': 0.16; 'from:addr:wlfraed': 0.16; 'from:name:dennis lee bieber': 0.16; 'place:': 0.16; 'received:66.245': 0.16; 'received:dsl.mindspring.com': 0.16; 'received:mindspring.com': 0.16; 'received:wlfraed': 0.16; 'shifts': 0.16; 'url:netcom': 0.16; 'url:wlfraed': 0.16; 'wulfraed': 0.16; 'wed,': 0.17; 'repeated': 0.18; 'url:home': 0.21; "doesn't": 0.22; 'sep': 0.23; 'url:wiki': 0.25; '(the': 0.28; 'lee': 0.28; '"+"': 0.30; 'usually': 0.32; 'probably': 0.33; 'to:addr:python-list': 0.33; 'normally': 0.34; 'header:X -Complaints-To:1': 0.35; 'rather': 0.35; 'charset:us-ascii': 0.36; 'subject:skip:m 10': 0.37; 'received:org': 0.38; 'steven': 0.38; 'url:org': 0.38; 'subject:: ': 0.39; 'url:en': 0.39; 'header:Mime- Version:1': 0.39; 'to:addr:python.org': 0.39; 'hit': 0.40; 'entered': 0.40; 'results': 0.61; 'dennis': 0.77; '2);': 0.84; 'article,': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Dennis Lee Bieber Subject: Re: Floating point multiplication in python Date: Tue, 06 Sep 2011 23:35:41 -0700 Organization: > Bestiaria Support Staff < References: <2204592.egLE2XKegd@PointedEars.de> <4e66f843$0$29969$c3e8da3$5496439d@news.astraweb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: user-11fa5ec.dsl.mindspring.com X-Newsreader: Forte Agent 3.3/32.846 X-No-Archive: YES 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: 23 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1315377360 news.xs4all.nl 2489 [2001:888:2000:d::a6]:37422 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:12878 On Wed, 07 Sep 2011 14:51:13 +1000, Steven D'Aprano declaimed the following in gmane.comp.python.general: > What you probably mean to say is that binary hardware usually implements > multiplication via repeated addition. > > http://en.wikipedia.org/wiki/Binary_multiplier > Technically, as shown by that article, binary multiplication is not what is commonly thought of "repeated addition" (the method used on old adding machines wherein one hit "+" /n/ times [though one normally entered a "0" for each place: rather than hit "+" 20 time for 123 * 20, on would hit 123, 0 "+", enter a 0 {giving 1230}, then hitting 2 "+"]). In binary most of the subparts are the results of left shifts (factors of 2); so "repeated" doesn't really apply... Multiple shift/add OTOH... -- Wulfraed Dennis Lee Bieber AF6VN wlfraed@ix.netcom.com HTTP://wlfraed.home.netcom.com/