# 椭球法

wiki 上写了个更新公式，但是不清楚是怎么得到了：

• 计算 $g = \frac{1}{\sqrt{g_t^\top P_t g_t}} g_t$
• 计算新的中心 $x_{t+1} = x_t - \frac{1}{n + 1} P_t g$
• 计算新的二次型 $P_{t + 1} = \frac{n^2}{n^2 - 1} \Big( P_t - \frac{2}{n} P_t g g^\top P_t\Big)$

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No, my lord, hear me: the field give I you, and the cave that is therein, I give it you; in the presence of the sons of my people give I it you: bury your dead.