Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.fsmpi.rwth-aachen.de!rt.uk.eu.org!newsfeed.xs4all.nl!newsfeed1a.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!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 0.024 X-Spam-Evidence: '*H*': 0.95; '*S*': 0.00; 'cc:addr:python-list': 0.11; '*should*': 0.16; 'dict': 0.16; 'exception?': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'nan': 0.16; 'nans': 0.16; 'zero.': 0.16; 'wrote:': 0.18; 'wed,': 0.18; 'all,': 0.19; 'cc:addr:python.org': 0.22; "shouldn't": 0.24; 'cc:2**0': 0.24; 'header:In-Reply-To:1': 0.27; 'chris': 0.29; 'am,': 0.29; 'message-id:@mail.gmail.com': 0.30; 'comparison': 0.31; 'division': 0.31; "i'd": 0.34; 'could': 0.34; "can't": 0.35; 'equal': 0.35; 'operations': 0.35; 'received:google.com': 0.35; 'rather': 0.38; 'does': 0.39; 'jul': 0.74; 'surprise': 0.74; 'subject:For': 0.78; 'to:none': 0.92 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:cc :content-type; bh=jkLtpFmZz3QQoPsXnpCEau1zUAUta2DZNigAiurfWyA=; b=k0Zay1UyQAA9H+c1OVrCDCG74hp/VM5ciIydE5FkIKVXbLaXn0d6Yqy1w6Mbm5jeUx npA/GNmttDfNbgBh9s7m1zKIacDZqhL5JJaD0PRxQrcHyONDfcy6Ypl0SB96zdMBh8Sd ijQwfNfC3FjgXFzQITqPy5LFPNI9hCwRcNyLkkHLbzptwDDFoizetlGMWliPJT2kYabM MGeEMVBYtuWHbOa3wH8iTd+mcCwV038EfijMStBe/2WkjEdaqqh6YickyX3xFTapZs/H Ffwvd3dW+K0nPMZLbqJ8l8IxsZnjpoeYKJGdeLpef9/FI4N5JSFnIAUcebcCPEE5jjQK 2nzg== MIME-Version: 1.0 X-Received: by 10.52.52.167 with SMTP id u7mr1073865vdo.70.1404836829152; Tue, 08 Jul 2014 09:27:09 -0700 (PDT) In-Reply-To: <878uo3akqy.fsf@elektro.pacujo.net> References: <53BC05FB.4050707@jmunch.dk> <878uo3akqy.fsf@elektro.pacujo.net> Date: Wed, 9 Jul 2014 02:27:09 +1000 Subject: Re: NaN comparisons - Call For Anecdotes From: Chris Angelico Cc: "python-list@python.org" Content-Type: text/plain; charset=UTF-8 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 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: 13 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1404836832 news.xs4all.nl 2855 [2001:888:2000:d::a6]:43001 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:74182 On Wed, Jul 9, 2014 at 2:16 AM, Marko Rauhamaa wrote: > Chris Angelico : > >> Why *should* all NaNs be equal to each other? > > I appreciate why you can't say NaN is equal to NaN. However, shouldn't > the very comparison attempt trigger an arithmetic exception? After all, > so does a division by zero. I'd say it would surprise people rather a lot if operations like dict insertion/lookup could trigger arithmetic exceptions. :) ChrisA