For the Poincaré half-space model in dimension 2, the metric evaluates on the coordinate tangent vectors \(\frac{\partial}{\partial x}, \frac{\partial}{\partial y} \in T_pM\) as \[g_p\!\left(\frac{\partial}{\partial x^i}\bigg|_p,\;\frac{\partial}{\partial x^j}\bigg|_p\right) = \frac{1}{y^2}\,\delta_{ij},\] i.e. the coordinate tangent vectors are orthogonal and each has length \(\frac{1}{y}\) — shrinking to zero as \(p\) approaches the boundary \(y\to 0\), which is what makes the space “infinitely large” near the boundary.
Фото: Дмитрий Макеев / РИА Новости
，推荐阅读51吃瓜获取更多信息
在奋进的春天里以“质”取胜（人民论坛网评），更多细节参见服务器推荐
aspect_ratio: ${16:9/21:9……}，这一点在旺商聊官方下载中也有详细论述