# [Maxima] eigen vectors and eigen values

Javed Alam jalam1001 at gmail.com
Wed Jun 18 13:36:43 CDT 2008

```I have used eigens_by_jacobi in the past for finding the eigen values and
vectors where symbolic method failed and it worked fine.

Javed

On Wed, Jun 18, 2008 at 2:15 PM, Raymond Toy (RT/EUS) <
raymond.toy at ericsson.com> wrote:

> Chibisi Chima-Okereke wrote:
> > Dear all,
> >
> > I am probably doing something silly and don't realise it but here goes...
> >
> > I am trying to find the eigen values and eigen vectors of a matrix, but
> > maxima keeps giving me an error (run on win XP in wxMaxima)
> >
> > (%i37)E:
> >
> matrix([1,-1,0,0,0,0,0],[-1,3,-1,0,-1,0,0],[0,-1,3,-1,0,-1,0],[0,0,-1,3,0,0,-1],[0,
> >  -1,0,0,3,-1,0],[0,0,-1,0,-1,4,-1],[0,0,0,-1,0,-1,4]);
> >
> > (%o37)
> >
> matrix([1,-1,0,0,0,0,0],[-1,3,-1,0,-1,0,0],[0,-1,3,-1,0,-1,0],[0,0,-1,3,0,0,-1],[0,-1,0,0,3,-1,0],[0,0,-1,0,-1,4,-1],[0,0,0,-1,0,-1,4])
> >
> > (%i38) eigenvalues(E);
> >
> > solve is unable to find the roots of the characteristic polynomial.
> >
> > (%o38) []
> >
> >
> Maxima wants to do this symbolically.  The characteristic polynomial is
> of order 7.  Do you know how to get symbolic roots from a 7'th order
> polynomial?  Neither does maxima. :-(
>
> > I have tried the same problem in R and I get an answer (in the blink of
> > an eye). Can anyone let me know what the problem is?
>
> Perhaps eigens_by_jacobi will do what you want.  Or you can load(lapack)
> and use dgeev to get the eigenvalues/vectors for this matrix.
>
> Ray
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