R help - Jul 2007 - Is there a facility in R similar to MatLab "syms" that allows using unevaluated numeric symbols in matrices?

Hi,


I'm trying to use R to get eigenvalues and eigenvectors of a matrix 
whose elements are of the form (2 * lambda), -(lambda + mu), etc.  I'd 
like R to treat this matrix as a numeric matrix without treating lambda 
and mu as variable names but rather as some sort of atomic quantities 
(and hence give eigenvectors in terms of mu and/or lambda).  MatLab and 
Mathematica both do this, but I'm not sure whether R does.  Does anyone 
have any ideas about how to do this?


Please let me know,
Dylan

Dylan Arena <darena <at> stanford.edu>
writes:
> 
> Hi,
> 
> I'm trying to use R to get eigenvalues and eigenvectors of a matrix 
> whose elements are of the form (2 * lambda), -(lambda + mu), etc.  I'd 
> like R to treat this matrix as a numeric matrix without treating lambda 
> and mu as variable names but rather as some sort of atomic quantities 
> (and hence give eigenvectors in terms of mu and/or lambda).  MatLab and 
> Mathematica both do this, but I'm not sure whether R does.  Does anyone
> have any ideas about how to do this?
> 
> Please let me know,
> Dylan
> 
You are asking for a Computer Algebra problem and thus you should apply a
Computer Algebra System (CAS) such as Maple, Mathematica, MuPAD, or the
free software Maxima.
By the way, Matlab does _not_ do this, it utilizes the Maple kernel in its
Symbolic Toolbox.
In R you can try the Ryacas package, but I personally would prefer one of
the more extended systems. Maxima with wxMaxima interface is quite nice,
and for MuPAD there is a non-expensive personal copy available.

Hans Werner Borchers
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