Catalan Surface

            Catalan Minimal Surface Parametric  Equations

  x = cos(aa*pi)*(u-sin(u)*cosh(v))+sin(aa*pi)*(v-cos(u) * sinh(v))-4
  y = cos(aa*pi) * (1 - cos(u) * cosh(v)) + sin(aa*pi) * sin(u) *sinh(v)
  z = 4 *sin(aa*pi)*(cos(u /2)*cosh(v/2)-1)+4*cos(aa*pi)*sin(u/2)*sinh(v/2)