MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Eigensystem[] for higher dimensions?


Yes. Use Eigensystem.
For instance

M = {{2, 0, -3}, {3, 5, 6}, {1, 1, -1}};esys = Eigensystem[M];

The diagonal matrix of the eigenvalues of M is given by

Lambda = DiagonalMatrix[esys[[1]]];

The matrix whose columns are the eigenvector of M by

A = Transpose[esys[[2]]];

Indeed

In[15]:= M.A-A.Lambda//Expand

gives

Out[15]= {{0,0,0},{0,0,0},{0,0,0}}


Adriano Pascoletti

AES wrote ..
> Can the matrix m in Eigensystem[m] be greater than two dimensional?
> 
> And the eigenvectors v correspondingly greater than one dimensional?
> 
> The problem of interest is finding the eigenvalues lambda and 
> eigenarrays A of the equation
> 
>    M A = lambda A
> 
> with A being a (physically nonseparable) two dimensional array and M a
> specified four dimensional array.  I can of course use appropriate 
> indexing to convert these to one and two dimensional quantities, but the
> index transformations can be a pain; the reverse index transformations
> even more ugly; the Mathematica Book doesn't seem to explicitly answer
> the question -- and it's easier to ask it here, and maybe also get some
> useful pointers, than futz around with experiments.
> 


  • Prev by Date: Re: Using Map with function that has options...
  • Next by Date: Re: Two strange problems with a notebook...
  • Previous by thread: Re: Deleting charachter from a text file
  • Next by thread: Newbie question about column sums of arrays