Dini's surface - Alchetron, The Free Social Encyclopedia

In geometry, Dini's surface is a surface with constant negative curvature that 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 + ln ⁡ tan ⁡ v 2 ) + b u

Another description is a helicoid constructed from the tractrix.

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