Choosing Perl/Python for my particular niche

[zatoichi]

Cameron Laird wrote:
> In article <40657D14.3FBE7E82 at doe.carleton.ca>,

> My current instinct is that you'll be happiest with Perl--
> but it's a close choice, all around.  I'm most accomplished
> in Tcl, and would happily use it, or Perl, or Python.  It
> seems to me, though, that it's crucial that you be able
> to exploit libraries that pertain to your domain, and, in
> particular, optimized engines for linear algebra, graph
> theory, and linear and mathematical programming.  Tcl 
> lacks the weight that Perl and, to an increasing extent,
> Python can boast in their libraries.
Since you happily use Perl, Python or Tcl, I have a question. How do you 
decided which one to use?  :-)

Robert