Maths definition

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Maths definition

MichaelAtOz
Administrator
I don't want to incorrectly name my shapes.

Is the result of resizing a circle like

resize([100,50]) circle(10);

technically, an ellipse?

If you make an ellipse into 3D for example

hull() {
    resize([100,50]) cylinder(r=10,h=0.1);
    translate([0,0,10])
        scale([0.8,0.8,1])  // tapered
        resize([100,50]) cylinder(r=10,h=0.1);
}

What is the right Mathematical name for such a shape?
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Re: Maths definition

stonysmith
Well.. if you ask a jeweler, they'd say it was oval <GRIN>
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Re: Maths definition

nophead
In reply to this post by MichaelAtOz
I think it is a truncated elliptic cone.

On 15 February 2015 at 00:22, MichaelAtOz <[hidden email]> wrote:
I don't want to incorrectly name my shapes.

Is the result of resizing a circle like

resize([100,50]) circle(10);

technically, an ellipse?

If you make an ellipse into 3D for example

hull() {
    resize([100,50]) cylinder(r=10,h=0.1);
    translate([0,0,10])
        scale([0.8,0.8,1])  // tapered
        resize([100,50]) cylinder(r=10,h=0.1);
}

What is the right Mathematical name for such a shape?



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Re: Maths definition

hagen
In reply to this post by stonysmith
An elipse is an oval, but an oval is not an elipse.

linear_extrude(height = 10, center = true, convexity = 10, twist = 0, slices = 20, scale = .8) {
        scale([1, 0.5]) circle(r=50);
}

would be in theory more correct, but I can imagine that in practice the hull solution works better.
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Re: Maths definition

hagen
so, yes it is a tapered elliptical cone