Dawn McKnight wrote:
>>   Unfortunately, I don't think there is any easy solution for the general
>> case.
>
>Maybe someone can help me with my math, then.
>
>I have a sphere scaled to <40, 54, 9.2>.  I wanted to place a row of
>holes along a parabolic surface that would match the curve of the elipse
>in the XY plane.
>
>I came up with f(x) = 0.04909(27.5-x)^2+37.125, which produces a
>parabola that matches the x and y intercepts, but the sides are too flat.
>
>I think if I could find a point that wasn't an intercept, I could come
>up with a better parabolic model, but I don't know how to do that, short
>of (extensive) trail and error.
>
>Suggestions?  Anyone?
>


Dawn,
Where did you derive your f(x)  equation from?

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?
I tested this equation against a scaled sphere you cited and it
seemed to work.

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

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

Hope this helps,
Sorry if I misinterpreted something
Tony

ton### [at] xenomechanicscom

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