ピタゴラス加算
\(c = \sqrt{a^2 + b^2}\) を面倒に計算する代わりに、<i>α-最大＋β-最小</i>アルゴリズムを使って \(\hat{c} = \mathrm{max}\left(a, 0.9a + 0.5b \right)\) と推定すれば、実際の \(c\) に非常に近い値を暗算で求められる。これは分散の寄与を合計したり、半径を求めたりする際に便利な手法である。
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