Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.fsmpi.rwth-aachen.de!newsfeed1.swip.net!uio.no!news.tele.dk!news.tele.dk!small.news.tele.dk!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 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'interpreter': 0.05; 'anders': 0.09; 'linear': 0.09; 'raises': 0.09; 'things,': 0.09; 'cc:addr:python-list': 0.11; 'python': 0.11; 'fancy': 0.16; 'from:addr:pobox.com': 0.16; 'from:addr:skip': 0.16; 'nan': 0.16; 'propagated': 0.16; 'sorts': 0.16; 'exception': 0.16; 'sender:addr:gmail.com': 0.17; 'wrote:': 0.18; 'all,': 0.19; 'written,': 0.19; 'cc:addr:python.org': 0.22; 'certainly': 0.24; 'instead.': 0.24; 'skip': 0.24; 'cc:2**0': 0.24; 'header:In-Reply- To:1': 0.27; 'appear': 0.29; 'am,': 0.29; 'generally': 0.29; 'message-id:@mail.gmail.com': 0.30; 'bad.': 0.31; 'crash': 0.31; 'community': 0.33; 'running': 0.33; 'computing': 0.35; 'received:google.com': 0.35; 'add': 0.35; 'there': 0.35; 'raising': 0.36; 'doing': 0.36; 'most': 0.60; 'jul': 0.74; 'subject:For': 0.78; 'computation,': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=ZwpTb2O+mWzlwQt09dunP1Kl38/6on9PDdJlw02mM7Y=; b=oSNFqt5PKydmh8YkZzXdUvqym4y/cerAJCQXUX6X1FnTTnVYCHcRZaAygInoFG6XYz iBTqsMhq11/2zZ2QgR7zEAAJWLtp+6/vy7kd8/PBwOvSEpyMX8odCvzs5tNGO3WL02xF Q44BsZCvG6MBcYEwcKxkXd/LxoEBMY1MwvUrvQYSfTTPZFkdTWPOzRsCJrLsnUdmTSbn 5lGVt5Xha58FTMUhMs3S0N6OeS9YcJCD5hpl3lEC1peQ9g/v/jNp7fj4k94cwSLwllDI sR04sGTXHlsBl48QzxbI5FIlSrxOfgGnj75xMNbrDVmCLqE5uMkvRBnN60Gd05sgNmHN hEDg== MIME-Version: 1.0 X-Received: by 10.50.56.84 with SMTP id y20mr5674933igp.8.1404840237537; Tue, 08 Jul 2014 10:23:57 -0700 (PDT) Sender: skip.montanaro@gmail.com In-Reply-To: <53BC05FB.4050707@jmunch.dk> References: <53BC05FB.4050707@jmunch.dk> Date: Tue, 8 Jul 2014 12:23:57 -0500 X-Google-Sender-Auth: w9sT3ibI8-VlqjCo35Q-CMCQayw Subject: Re: NaN comparisons - Call For Anecdotes From: Skip Montanaro To: "Anders J. Munch" <2014@jmunch.dk> Content-Type: text/plain; charset=UTF-8 Cc: Python 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: 1404840246 news.xs4all.nl 2935 [2001:888:2000:d::a6]:47579 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:74188 On Tue, Jul 8, 2014 at 9:53 AM, Anders J. Munch <2014@jmunch.dk> wrote: > Most people don't need to deal with NaN's in Python at all, > fortunately. They just don't appear in normal computation, because the > interpreter raises an exception instead. In addition to what others have written, I will add one thing. There are certainly situations where raising an exception is bad. Consider all the people in the scientific computing community doing fancy linear algebra sorts of things, often with missing data. They generally want NaN propagated and not have some long running calculation crash in the middle. Skip