这个不就是黎曼球面吗？

the Riemann sphere, named after Bernhard Riemann,^[1] is a model of the extended complex plane, the complex plane plus a point at infinity. This extended plane represents the extended complex numbers, that is, the complex numbers plus a value ∞ for infinity.

 

The extended complex numbers consist of the complex numbers C together with ∞. The set of extended complex numbers may be written as C∪ {∞}, and is often denoted by adding some decoration to the letter C, such as

${\displaystyle \hat{\mathbb{C}},\overline{\mathbb{C}},\text{or}{\mathbb{C}}_{\mathrm{\infty }}.}$

所有跟帖： 

• 有点儿不同。你可以网上查查。俺当时看完时的理解是， -红色娘子军志愿参谋- ♀ (192 bytes) () 10/20/2017 postreply 11:19:27