p-Norm Unit Sphere (superellipsoid, p knob)
p-Norm Unit Sphere (superellipsoid, p knob) is an algebraic surface, defined by an implicit equation, immersed.
Open p-Norm Unit Sphere (superellipsoid, p knob) in the interactive viewer →
algebraic aperiodic closed closed-orientable def-implicit immersed implemented tradition-classical
Formula
Properties
- Family
- algebraic
- Given by
- an implicit equation
- Curvature
- no condition imposed
- Periodicity
- not periodic
- Ends
- 0
- Embedding
- immersed
- Orientable
- yes
- Fidelity
- exact
- Exactness
- elementary
Definition
The unit spheres of the p-norms on R3 (the equal-exponent Lame / superellipsoid family): |x|^p + |y|^p + |z|^p = 1, octahedron at p = 1, sphere at p = 2, cube as p -> infinity, convex for p >= 1. SHIPPED with p as a live knob (default 4); gated on two exact identities -- the p = 2 member IS the unit sphere (|F| = 0 on it) and every member is invariant under the full order-48 octahedral group.
Sources
Closed form reproduced numerically against the shipped implementation (math_art/surfaces/algebraic.py) over 240 sample points: matches oracle x 1 over 240 points (worst 0).
- E. W. Weisstein, "Peano Surface", "Chair", "Crossed Trough", "Handkerchief Surface", "Hunt's Surface", "Kiss Surface", "Menn's Surface", "Miter Surface", "Nordstrand's Weird Surface", "Tooth Surface", MathWorld -- A Wolfram Web Resource, mathworld.wolfram.com.
- T. Nordstrand, "Weird Cube" and the tooth/pillow object, per the MathWorld pages (Nordstrand 1997).
- G. Peano's 1899 counterexample; cf. the MathWorld page's history of the criterion it defeated.
- The 3DXM Consortium, 'Norm One Family', Virtual Math Museum, virtualmathmuseum.org (local mirror: vmm/book/surface/ch080_norm_one_family.md).