Superellipse
A superellipse, also known as a Lamé curve after Gabriel Lamé, is a closed curve resembling the ellipse, retaining the geometric features of semi-major axis and semi-minor axis, and symmetry about them, but a different overall shape.
In the Cartesian coordinate system, the set of all points (x, y) on the curve satisfy the equation
where n, a and b are positive numbers, and the vertical bars | | around a number indicate the absolute value of the number.
This formula defines a closed curve contained in the rectangle −a ≤ x ≤ +a and −b ≤ y ≤ +b. The parameters a and b are called the semi-diameters of the curve.
For n = 1/2, in particular, each of the four arcs is a segment of a parabola.
The curvature increases without limit as one approaches its extreme points.
The curvature is zero at the points (±a, 0) and (0, ±b).
If n < 2, the figure is also called a hypoellipse; if n > 2, a hyperellipse.
When n ≥ 1 and a = b, the superellipse is the boundary of a ball of R2 in the n-norm.
The extreme points of the superellipse are (±a, 0) and (0, ±b), and its four "corners" are (±sa, ±sb), where (sometimes called the "superness").
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