Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed1.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 0.029 X-Spam-Evidence: '*H*': 0.94; '*S*': 0.00; 'python': 0.09; 'part,': 0.09; 'solution,': 0.09; 'equation.': 0.16; 'equations': 0.16; 'formula': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'messy': 0.16; 'side.': 0.16; 'solver': 0.16; 'subject:stuck': 0.16; 'wed,': 0.16; 'wrote:': 0.17; 'jan': 0.18; 'appears': 0.18; 'bit': 0.21; 'programming': 0.23; 'references': 0.23; "haven't": 0.23; 'header:In-Reply-To:1': 0.25; 'am,': 0.27; 'message-id:@mail.gmail.com': 0.27; 'chris': 0.28; 'basic': 0.30; 'point': 0.31; 'problem.': 0.32; 'function.': 0.33; 'true.': 0.33; 'to:addr:python-list': 0.33; 'likely': 0.33; 'received:google.com': 0.34; 'problem,': 0.35; 'solving': 0.35; 'received:209.85.220': 0.35; 'received:209.85': 0.35; 'there': 0.35; 'but': 0.36; 'useful': 0.36; 'two': 0.37; 'received:209': 0.37; 'subject:: ': 0.38; 'to:addr:python.org': 0.39; 'where': 0.40; 'header:Received:5': 0.40; 'end': 0.40; 'your': 0.60; 'most': 0.61; 'solve': 0.62; 'necessarily': 0.63; 'more': 0.63; '2013': 0.84; 'equation,': 0.84; 'isolate': 0.84; 'angel': 0.93; 'average': 0.93 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:to :content-type; bh=xu/gg6jAuhF69X7t146sU/3Ih2c2SkMiapBAHB8oD3M=; b=kWWv/GXxfk0mWvJiQf3SwwihmgJakwfUPMaR5benwIg25qAMnDnVlNI+35WU+KEex1 VrWDqlmjZANqzPxaWIGJTAC/+dVzOvy4x09PoVptIXlopd5OChV+VnU8UVP+7vdnLsOR vTUdw78Lrq36daGp/XXXUEtzxkIvStqgS8GShFDytY5lmDD4JI9JFW/f0p9kGxtok/NJ wLKpD7ykcDpTQdD4uxiWHo/Z+N163EUi3atWeZ8JuoNy9QM7cvoUmtD/poJQYcLLOiSK 0UqEfG9BsCEie2WSaMnY00gaBUD8BPYXpy51fMQEAa/fJDNuBmev5tsWLtVWVDrhQD6a rl/Q== MIME-Version: 1.0 In-Reply-To: <50E311F4.2080501@davea.name> References: <2043e377-00d8-49d7-a35a-0c52c869f70f@googlegroups.com> <50E311F4.2080501@davea.name> Date: Wed, 2 Jan 2013 04:44:46 +1100 Subject: Re: got stuck in equation From: Chris Angelico To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 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: 23 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1357062295 news.xs4all.nl 6887 [2001:888:2000:d::a6]:47846 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:35899 On Wed, Jan 2, 2013 at 3:42 AM, Dave Angel wrote: > On 01/01/2013 11:03 AM, Chris Angelico wrote: >> This isn't a Python question, it's an algebra one. I don't know what >> Z, S, and so on are, but for the most part, the basic rule of solving >> equations applies: Do the same thing to both sides and it's still >> true. Work on it until you can isolate SN on one side. > > Such a rule may not be able to solve an equation when there SN appears > more than once on the RHS, and where it's inside a transcental > function. I don't consider this an algebra problem, but a programming > problem. It's a tad more complicated than your average equation, and I haven't the time now to prove the point by actually solving it, but every operation that I can see in that formula can be reversed. The hairy bit is that there are two references to SN, so it's going to be a bit messy to untangle, and might end up as a higher-order equation. But you're likely right that other forms of solver may be more useful here. Algebra definitely _could_ be the solution, but it isn't necessarily the best. ChrisA