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MathGroup Archive 1996

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Re: Q: Eigen values in Mathematica 2.2

  • To: mathgroup at smc.vnet.net
  • Subject: [mg4042] Re: Q: Eigen values in Mathematica 2.2
  • From: ianc (Ian Collier)
  • Date: Tue, 28 May 1996 01:46:53 -0400
  • Organization: Wolfram Research, Inc.
  • Sender: owner-wri-mathgroup at wolfram.com

In article <4noq7d$71h at dragonfly.wolfram.com>, wojtek at amedec.amg.gda.pl
(Wojciech Piotrowski) wrote:

> Why Mathematica 2.2 can't find Eigen values for some matrices? When I use
> the earlier version ( 2.1 ) there is no problem like that. For example:
>    Amat={{1,2},{-2,-3}};
>    Eigenvalues[Amat]
> And version 2.2 displays message: can't find all roots of charactristic
> polynomial, but v.2.1 answers: {-1,-1}
> This no matters when I want to find only Eigen values, because I can find
> it solving characteristic polynomial for instance, but Mathematica use 
> Eigenvalues function in JordanDecomposition which I often use.
>                                         wojtek at amedec.amg.gda.pl


This appears to work correctly in the current Macintosh, Windows 
and Unix versions of Mathematica that I have access to:

In[1]:=
    Eigenvalues[ {{1,2},{-2,-3}} ]
Out[1]=
    {-1, -1}
In[2]:=
    $Version
Out[2]=
    Power Macintosh 2.2 (February 24, 1994)

Is it possible that you have changed the definition of the 
Eigenvalues function?

My best suggestion would be to contact Wolfram Research Technical 
Support (in your case support at wolfram.co.uk) directly including
full details of your copy of Mathematica and also the computer you
are running it on.

I hope this helps.

--Ian

-----------------------------------------------------------
Ian Collier
Wolfram Research, Inc.
-----------------------------------------------------------
tel:(217) 398-0700   fax:(217) 398-0747    ianc at wolfram.com
Wolfram Research Home Page:         http://www.wolfram.com/
-----------------------------------------------------------

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