The Gyroid like the Lance of Longinus in Neon Genesis Evangelion(*1).
The Gyroid's equation is:
[math] \sin x \cos y + \sin y \cos z + \sin z \cos x = 0 [/math]
and it is reduced to:
[math] z = \arcsin(- \frac{\sin x \cos y}{\sqrt{\cos^{2} x + \sin^{2} y}} - \frac{\sin y}{\cos x}) [/math]
(*1) Neon Genesis Evangelion is Japanese Animation:
https://en.wikipedia.org/wiki/Neon_Genesis_Evangelion
