Infinity and Undefined

[Richard B. Kreckel]

On Thu, 15 Nov 2001, Pearu Peterson wrote:
> > BTW, what's a FieldNumber?
> 
> I was thinking of quaternions (though they form skew field). However
> introducing such objects to GiNaC may not be simple. And I am not sure if
> you are interested in such an extension.

Hmm, quaternions would just be another indexed object, I think.  You
certainly don't want to use an explicit 2x2 matrix representation, would
you?  On the other hand, it would probably be more reasonable implementing
Pauli matrices in a fashion completely analogous to class color.  Then,
the quaternions i, j and k are just related with these by
     sigma_x = I*i,   sigma_y = I*j,   sigma_z = I*k,
together with the unity sigma_ONE.

Cheers
    -richy.
-- 
Richard B. Kreckel
<Richard.Kreckel at Uni-Mainz.DE>
<http://wwwthep.physik.uni-mainz.de/~kreckel/>