Tony LaVigne wrote:
> Dawn,
> Where did you derive your f(x)  equation from?

Hey, Tony.

First of all, let me sy thanks for your assistance... I'm really a math 
idiot trying to make it in a big world.

My function is derived from the standard parabolic form y = a(x-h)^2 +k, 
where h, k are the x, y coordinates of the vertex.  Since I want a 
parabolic section (or an elipsoidal section) that matches the shape of 
the outer edge, without actually being at the outside edge (in this 
case, I want the x intercepts at +/- 27.5, y at 37.125), I find that the 
  coordinates of the vertex are (0, 37.125).  Plug and chug, and you get 
the equation I provided.

> Is the general equation for this sphere
> 1= (  (x-Xo)/40  )^2 + ( (y-Yo)/54  )^2  +( (z-Zo)/9.2 )^2   where
> (Xo,Yo,Zo) is the center of the sphere?

Uh... I'm not sure.  Is that right?  You're setting it equal to one? 
Why not zero?  I'm confused.

I looked at the equation for the superquadratic elipsoid, which is in 
the docs, but it doesn't look like yours, and I'm not math-knowledgeable 
enough to get from one form to the other.

> If so, and if the center of the sphere is (0,0,0) and your XY plane is at
> z=0, then the equation might boil down to

That's a reasonable aproximation, yes.

> y= f(x) = sqrt{ [1-(x/40)^2] / [54^2]  }

When I plot that on my graphing calculator, I get an elipsoid shape that 
has the right x intercepts... but the y intercept is off by a factor of 
a thousand.

I'm not clever enough to figure out how to correct it....

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