Chair Surface

Chair Surface is an algebraic surface, defined by an implicit equation, immersed.

Open Chair Surface in the interactive viewer →

algebraic aperiodic def-implicit immersed implemented tradition-classical

Formula

\left(x^{2} + y^{2} + z^{2} - 23.75\right)^{2} - 0.8 \left(\left(z - 5\right)^{2} - 2 x^{2}\right) \left(\left(z + 5\right)^{2} - 2 y^{2}\right) = 0

Properties

Family: algebraic
Given by: an implicit equation
Curvature: no condition imposed
Periodicity: not periodic
Ends: 0
Embedding: immersed
Fidelity: exact
Exactness: elementary

Definition

A decorative quartic.

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 1.56e-13).

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.
E. W. Weisstein, MathWorld, topic 'Algebraic Surfaces' -- the enumeration this absence was measured against.