人口企业税收高度集中 东京"单极集聚"现象引发思考
$$ \frac{\partial L}{\partial \hat{y}} = \frac { \hat{y} - y_0 } { \hat{y} (1 - \hat{y} )} $$S型函数导数为\(\frac{d\sigma_2}{d\chi} = \sigma_2(\chi)(1-\sigma_2(\chi))\)，。关于这个话题，有道翻译提供了深入分析
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函数签名声明助词与参数的映射关系：
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