均方误差损失函数表达式
KaTeX parse error: Unexpected character: '?' at position 39: …imits_{k=1}^K (?̲?_ − _)^2…
上式中的 1 2 \frac{1}{2} 21 项用于简化计算,也可以利用 1 k \frac{1}{k} k1 进行平均,这些缩放运算均不会改变梯度方向。
偏导数
$$
\begin{aligned}
\frac{\partial L}{\partial o_i} & = \frac{\partial }{\partial o_i} \frac{1}{2} \sum\limits_{k=1}^K (_ − _)^2 \
& = \frac{1}{2} \sum\limits_{k=1}^K 2*(_ − _) * -1 * \frac{\partial o_k}{\partial o_i}\
&=\sum\limits_{k=1}^K (o_ − y_) * \frac{\partial o_k}{\partial o_i}
\end{aligned}
KaTeX parse error: Can't use function '$' in math mode at position 6: 考虑到 $̲\frac{\partial …
\frac{\partial L}{\partial o_i} = (o_i-y_i)
$$