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?

Unless specifically shown otherwise above, my contribution is in the Public Domain; To the extent possible under law, I have waived all copyright and related or neighbouring rights to this work. This work is published globally via the internet. :) Inclusion of works of previous authors is not included in the above.

The TPP is no simple “trade agreement.”  Fight it! http://www.ourfairdeal.org/

View this message in context: http://forum.openscad.org/Maths-definition-tp11633.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

Well.. if you ask a jeweler, they'd say it was oval <GRIN>
http://forum.openscad.org/file/n11634/stone-shapes-their-names-15970614.jpg

--
View this message in context: http://forum.openscad.org/Maths-definition-tp11633p11634.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

An  elipse https://en.wikipedia.org/wiki/Ellipse  is an oval, but an  oval
https://en.wikipedia.org/wiki/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.

--
View this message in context: http://forum.openscad.org/Maths-definition-tp11633p11637.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

so, yes it is a tapered elliptical cone

--
View this message in context: http://forum.openscad.org/Maths-definition-tp11633p11638.html
Sent from the OpenSCAD mailing list archive at Nabble.com.