User:AndrewDressel/Dini's surface

Dini's surface is a surface with constant negative curvature which can be created by twisting a pseudosphere. It is named after Ulisse Dini and described by the following parametric equations:
 * x = a cos(u) sin(v)
 * y = a sin(u) sin(v)
 * z = a (cos(v) + log(tan(v/2))) + b u

Reditions of Dini's surface have appeared on the covers of Western Kentucky University's Graduate Study in Mathematics, Gray's Modern Differential Geometry of Curves and Surfaces with Mathematica, Second Edition, and volume 2, number 3 of La Gaceta de la Real Sociedad Matemática Española.