Teaching maxima a new identity



All:

I have an expression involving a vector p = [u, v, w]'
for which it is known in advance that |p| == 1, i.e.
the point p lies on the unit sphere.  I am doing some
manipulations that result in equations involving the
expression u^2 + v^2 + w^2, and it would be nice if
Maxima would automatically replace this expression
with unity without me having to type 

ratsubst(1, u^2 + v^2 + w^2, %);

after every other command.  I'm getting Carpal Tunnel
over here.

Is there a way to do this?  I tried using the "::"
operator, which from the documentation, seems like it
should accomplish what I want, but:

1 :: u^2 + v^2 + w^2;

yields an "invalid assignment" error.
 
Related uestion: if this is not what "::" is
supposed to do, then what *does* it do, exactly?

Robert: I suggest you answer the question 'What is
the difference between ":" and  "::"' with examples in
your minimal-maxima guide.
 
Dan

P.S. Has anyone ever been able to successfully post a
new topic to this group through the gmane.org web
interface?  Every time I try, the web interface seems
to accept my post, but withing five minutes, the mail
server bounces my post back at me.


	
		
__________________________________ 
Yahoo! Mail - PC Magazine Editors' Choice 2005 
http://mail.yahoo.com