hyperbolic disk | Poincaré disk

The Poincaré hyperbolic disk is a two-dimensional space having hyperbolic geometry defined as the disk {x element R^2 : left bracketing bar x right bracketing bar <1}, with hyperbolic metric d s^2 = (d x^2 + d y^2)/(1 - x^2 - y^2)^2.

elliptic plane | hyperbolic geometry | hyperbolic metric | Klein-Beltrami model | Poincaré metric