Английская Википедия:Dini's surface
Материал из Онлайн справочника
In geometry, Dini's surface is a surface with constant negative curvature that can be created by twisting a pseudosphere.[1] It is named after Ulisse Dini[2] and described by the following parametric equations:[3]
- <math>\begin{align}
x&=a \cos u \sin v \\ y&=a \sin u \sin v \\ z&=a \left(\cos v +\ln \tan \frac{v}{2} \right) + bu \end{align}</math>
Another description is a generalized helicoid constructed from the tractrix.[4]
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