#http://www.mathcurve.com/surfaces/minimale/minimale-catalan.shtml
vertices = D1:100 D2:400
u = from 0 to 1.6 D1
v = from (-4*PI) to (PI*4) D2
a = 10
x = a*[4*v - sin(2*v)*(1+2*u*u)]
z = a*cos(2*v)*(1+2*u*u)
y = 4*a*sin(v)*u
