From: Axel Etzold Date: 2007-11-21T20:30:59+09:00 Subject: Re: [Matrix] eigenvalues, eigenvectors in Ruby ??? -------- Original-Nachricht -------- > Datum: Wed, 21 Nov 2007 09:25:09 +0900 > Von: "M. Edward (Ed) Borasky" > An: ruby-talk@ruby-lang.org > Betreff: Re: [Matrix] eigenvalues, eigenvectors in Ruby ??? > Axel Etzold wrote: > > -------- Original-Nachricht -------- > >> Datum: Wed, 21 Nov 2007 00:47:45 +0900 > >> Von: "Cameron McBride" > >> An: ruby-talk@ruby-lang.org > >> Betreff: Re: [Matrix] eigenvalues, eigenvectors in Ruby ??? > > > >> On 11/20/07, M. Edward (Ed) Borasky wrote: > >>> One of the Summer of Code projects extends Matrix to do most of the > >>> common matrix operations. Try > >>> > >>> http://rubyforge.org/projects/matrix > > > > Dear Ed and Cameron, > > > >> That's kind of neat, I missed it. Thanks. > >> > > > > Me too. Very nice. > > > >> Do you know right off how its accuracy compares to GSL/LAPACK routines? > > > > Am I wrong in thinking that you can use that library without being > > forced to calculate in Floats, i.e. can one use Rationals, Sqrts, > > continued fractions, whatever as matrix entries ? > > > > Then, its accuracy should only be limited by the space available on > > the machine. > > > > Best regards, > > > > Axel > > Yes, one of the design goals was to support Rational arithmetic. But > unless the matrix is poorly-conditioned, you shouldn't have to do so, > and for real symmetric eigensolutions, the only problem with using > floating arithmetic would be if you have some pathologically close > eigenvalues you need to separate. > > I don't know about continued fractions ... I don't think that's in > there. If you want to do that, you'll need something like Maxima, Axiom > or Yacas. Or a special-purpose exact linear algebra library. > > Anybody up to do a Ruby binding to Yacas? There's an R binding to it, so > it can't be too difficult. There are also Java hooks, so this may be yet > another JRuby killer app. :) Dear Ed, it's very good that one doesn't have to do every calculation in Float or Double .. of course, Rationals and Symbolic computations can become very complex, but if one needs to do it, it's nice to know that Ruby has an option that can help. Best regards, Axel -- Ist Ihr Browser Vista-kompatibel? Jetzt die neuesten Browser-Versionen downloaden: http://www.gmx.net/de/go/browser