From help-octave-request at bevo dot che dot wisc dot edu Mon Jun 14 19:34:23 1999 Subject: Re: eigenvectors From: Daniel Heiserer To: eduardo at faceng dot anu dot edu dot au, "help-octave@bevo.che.wisc.edu" Date: Mon, 14 Jun 1999 10:50:47 +0200 eduardo at faceng dot anu dot edu dot au wrote: > > heberf at calvin dot wustl dot edu wrote: > > > > This may be a dumb question, forgive me, it's been too long. > > > > I have a real, square matrix Q and I need to factorize it as > > > > Q = inv(X)*D*X > > > > where D is diagonal. I think that this means that D contains the > > eigenvalues and X contains the eigenvectors of Q. Is that right? How do > > I get D and X from octave. The function svd gives the "right and left" > > eigenvectors for any matrix. I thought that for square matrices this > > would mean that it would return X but I was wrong. > > > > Sheepishly, > > Heber > > > > > > Well, the problem is that not every matrix can be factorized in that > way. In general, what one has is the _Jordan_ form. Furthermore, the > singular value decomposition (svd) is not directly related to your > problem. The situation is difficult to explain in just few lines, you > may want to consult a linear algebra textbook on the matter. > Yeah. Is there a [J,X]=jordan(X) function in octave, or can somebody contribute one? Bye daniel -- Mit freundlichen Gruessen Daniel Heiserer ----- -------------------------------------------------------------- Dipl.-Phys. Daniel Heiserer, BMW AG, Knorrstrasse 147, 80788 Muenchen Abteilung EK-20 Tel.: 089-382-21187, Fax.: 089-382-42820 mailto:daniel dot heiserer at bmw dot de --------------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. To ensure that development continues, see www.che.wisc.edu/octave/giftform.html Instructions for unsubscribing: www.che.wisc.edu/octave/archive.html ---------------------------------------------------------------------