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Re: QUESTION (EigenVectors)

  • To: mathgroup at
  • Subject: [mg19417] Re: QUESTION (EigenVectors)
  • From: adam.smith at
  • Date: Mon, 23 Aug 1999 13:57:24 -0400
  • Organization: - Share what you know. Learn what you don't.
  • References: <7pl79i$>
  • Sender: owner-wri-mathgroup at

Mathematica has built-in routines for finding the eigenvalues and
eigenvector of any n-by-n matrix.  See the help under List and
Matrices -> Matrix Operations -> EigenValues, EigenVectors and

EigenValues[matrix] gives you the roots of the n-degree polynomial.
EigenVectors[matrix] gives the EigenVector.
EigenSystem[matrix] gives both the eigenvalues and corresponding
eigenvector in one command.

Adam Smith

In article <7pl79i$ch0 at>,
  clangis at (Christian Langis) wrote:
> Hi there.
> I am a a computer science student; and that is probably why
> this question may seem deprived of any chalenge to you. But it
> is quite challenging to me.
> The question is: how do you extract the 1st EigenVector from a
> 3x3 matrix (and optionally 2nd and 3rd)?
> I read a solution which forces the person to extract the 3
> roots of a 3rd degree polynomial. And this has to be done by
> hand of course.
> Hence, it is possible to compute that manually. But I am rather
> looking for an algorithm do carry this task, a solution which
> does not involve any manual evaluation (such as root extraction).
> Therefore do you know any algorithm/source code to do that (or
> know where to find it)?
> thanks

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