appears as a triangle along the y-axis,
apprears as an astroid along the z-axis
and whose z-cross section are formed by ellipses.
appears as a half-ellipse along the y-axis,
appears as a circle along the z-axis.
x = (a+cos(u/2) sin(v) - sin(u/2) sin(2v)) cos(u) y = (a+cos(u/2) sin(v) - sin(u/2) sin(2v)) sin(u) z = sin(u/2) sin(v) + cos(u/2) sin(2v)
over the square [-2, 2] x [-2,2].
Construct the same surface located above the disc x^2+y^2<=4
12-10-2
as (x,y) ranges over the unit disc.