From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: * X-Spam-Status: No, score=2.0 required=5.0 tests=BAYES_00,FORGED_MUA_MOZILLA, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Thread: a07f3367d7,35f6cee6f665d64b X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit Received: by 10.66.77.35 with SMTP id p3mr3197635paw.44.1343789456110; Tue, 31 Jul 2012 19:50:56 -0700 (PDT) Path: p10ni9631378pbh.1!nntp.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!nrc-news.nrc.ca!goblin2!goblin.stu.neva.ru!aioe.org!.POSTED!not-for-mail From: "Nasser M. Abbasi" Newsgroups: comp.lang.ada Subject: Re: ANN: Ada 2005 Math Extensions 20120712 Date: Sun, 29 Jul 2012 09:52:08 -0500 Organization: Aioe.org NNTP Server Message-ID: References: <167ecede-3588-45f0-904b-06a8be4cfec7@googlegroups.com> <2ba72d4e-6e88-4900-8232-c075242dec1f@googlegroups.com> <65f76f80-a1e5-4c60-8002-45becc2a1198@googlegroups.com> <6ae0b4cc-5ef1-43c0-b93a-8d33408f1a77@googlegroups.com> <00b425bc-6af1-4062-be58-f98012d155c6@googlegroups.com> Reply-To: nma@12000.org NNTP-Posting-Host: 9ii5QNw33OfeoTzEH8w9ug.user.speranza.aioe.org Mime-Version: 1.0 X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20120713 Thunderbird/14.0 X-Notice: Filtered by postfilter v. 0.8.2 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Date: 2012-07-29T09:52:08-05:00 List-Id: On 7/29/2012 9:34 AM, Ada novice wrote: > On Sunday, July 29, 2012 3:22:46 PM UTC+1, Nasser M. Abbasi wrote: >> >> It is the other way around. >> > > Yes I know about eigenvalues and stability in the complex plane. This is why I > said that something would have been terribly wrong if Debian lapack and ACML were >not agreeing on the eigenvalues. > Sorry, I misunderstood you. somehow I read what you said as the eigenvalues were different. But different eigenvectors magnitudes is not a problem. It is not uncommon to see this: ----------------------------- Matlab: EDU>> A=[1 2; 3 4] EDU>> [eigVectors,eigValues]=eig(A) eigVectors = -0.8246 -0.4160 0.5658 -0.9094 eigValues = -0.3723 0 0 5.3723 ------------------------- Mathematica: ------------------------------ In[5]:= mat={{1,2}, {3,4}}; eigenVector=Eigenvectors[mat]//N Out[6]= {{0.457427,1.},{-1.45743,1.}} eigenVector=Eigenvalues[mat]//N Out[7]= {5.37228,-0.372281} ----------------------------- Maple: ----------------- A:=<<1|2>,<3|4>>: evalf(LinearAlgebra:-Eigenvectors(A)); [ 5.372281324] [0.4574271076 -1.457427107] [ ], [ ] [-0.372281324] [ 1. 1.] ----------------------- You see, eigenvealuses are all the same (as you also said :), but the eigenvectors have different normalization. Here Maple and Mathematica used the same. But Matlab was different. (using default call). --Nasser