Title: Bowl

Source: Borg and Groenen (2005)

Description: Data generated on the surface of a bowl. The points lie
on the surface of a 2D manifold that is a quadratic function of the
coordinates in the ground plane. The coordinates are for row i are
given by:

x_i = .5*sqrt(v_i)*cos(2*pi*u_i)
y_i = .5*sqrt(v_i)*sin(2*pi*u_i)
z_i = v_i-.5

for uniformly distributed v_i and u_i between zero and one.