反向传导算法

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<li>对于第 <math>\textstyle n_l</math> 层(输出层)的每个输出单元 <math>\textstyle i</math>,我们根据以下公式计算残差:
<li>对于第 <math>\textstyle n_l</math> 层(输出层)的每个输出单元 <math>\textstyle i</math>,我们根据以下公式计算残差:
-
:<math>  
+
 
-
\delta^{(n_l)}_i = \frac{\partial}{\partial z^{n_l}_i}J(W,b;x,y)
+
:<math>
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= \frac{\partial}{\partial z^{n_l}_i}\frac{1}{2} \left\|y - h_{W,b}(x)\right\|^2
+
\begin{align}
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= - (y_i - a^{(n_l)}_i) \cdot f'(z^{(n_l)}_i)
+
\delta^{(n_l)}_i
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</math>  
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= \frac{\partial}{\partial z^{(n_l)}_i} \;\;
 +
        \frac{1}{2} \left\|y - h_{W,b}(x)\right\|^2 = - (y_i - a^{(n_l)}_i) \cdot f'(z^{(n_l)}_i)
 +
\end{align}
 +
</math>

Revision as of 13:17, 9 April 2013

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