Nodary
In physics and geometry, the nodary is the curve that is traced by the focus of a hyperbola as it rolls without slipping along the axis, a roulette curve. The differential equation of the curve is: formula_1. Its parametric equation is: where formula_4 is the elliptic modulus and formula_5 is the incomplete elliptic integral of the second kind and sn, cn and dn are Jacobi's elliptic functions. The surface of revolution is the nodoid constant mean curvature surface.