I want to model a formula object as a paraboloid.  I've fiddled with the formulas some but don't see how to get to the paraboloid.  Can someone help.  Thanks.

The classic formula for an Elliptic paraboloid is :-
x2   y2
-- + -- = 2z
a2   b2

This translates to :-
a=2.0;
b=2.0;
t=30*(u-0.5);
s=30*(v-0.5);
x=t;
y=s;
z=(((tt) / (a * a)) + ((ss) / (b * b))) / 2.0;

If you want a Hyperbolic paraboloid substitute :-
z=(((tt) / (a * a)) - ((ss) / (b * b))) / 2.0;

Thanks.  That's exactly what I was looking for.

Can you point someplace I can learn about making that u,v translation?

See if any of these make sense (Google for "Parametric Surface" for others) :-
http://www.math.duke.edu/education/ccp/materials/mvcalc/parasurfs/para1.html
http://en.wikipedia.org/wiki/Parametric_surface
http://cs.jsu.edu/mcis/faculty/leathrum/Mathlets/parasurf.html

It was straight forward in this case as x and y are just scaled version of u and v, for other non-parametric surface definitions, things will be trickier.

Thanks.  This good stuff.  I expect to be working with some surfaces in the near future and these will be good resources for trying to depict them.

http://gianp.free.fr/carrara/indexcarrara.html

This is the HUGE list of Carrara formulae.