From: "M. Edward (Ed) Borasky" <znmeb@...>
Date: 2006-08-12T13:42:26+09:00
Subject: Re: Defining Eigenclass

Rick DeNatale wrote:
> On 8/11/06, Trans <transfire@gmail.com> wrote:
>> Google Singleton class. That'll surely help ;-)
>
> The 'official' ruby docs talk about singleton classes, but eigenclass
> seems to have been proposed by someone, somewhere, sometime as an
> alternative.
>
> This seems to be confined to the ruby community and provides the
> subtext for things like eigenclass.org, but I can't seem to find where
> the term came from originally.
>
> I'd love enlightenment on that.
>
> Now I guess that the etymology comes from the German word "eigen"
> which can be translated to "own" or "individual", and also forms the
> root of the mathematical terms "eigenvector" and "eigenvalue".  If we
> look at "eigenclass" from the perspective of "eigenvector" though, it
> doesn't fit that well, since an "eigenvector" of a transformation in
> linear algebra is a vector which is unchanged in direction (or more
> properly only changes by being multiplied by a scalar) under that
> transformation.
>
>
Hmpf ... I just realized that the typical definition of an eigenvector is

A vector 'x' such that 'A*x = lambda*x', where A is a square matrix. 
'lambda' is the eigenvalue.

So, was eigenclass named after the eigenvalue or the eigenvector?