反向传导算法

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  = \frac{\partial}{\partial z^{n_l}_i}\frac{1}{2} \left\|y - h_{W,b}(x)\right\|^2
  = \frac{\partial}{\partial z^{n_l}_i}\frac{1}{2} \left\|y - h_{W,b}(x)\right\|^2
  = \frac{\partial}{\partial z^{n_l}_i}\frac{1}{2} \sum_{j=1}^S_n_l(y_j-a_j^(n_l))^2
  = \frac{\partial}{\partial z^{n_l}_i}\frac{1}{2} \sum_{j=1}^S_n_l(y_j-a_j^(n_l))^2
-
= \frac{\partial}{\partial z^{n_l}_i}\frac{1}{2} \sum_{j=1}^S_n_l(y_j-f(z_j^(n_l)))^2
 
-
= - (y_i - f(z_j^(n_l))) \cdot f'(z^{(n_l)}_i)
 
-
= - (y_i - a^{(n_l)}_i) \cdot f'(z^{(n_l)}_i)
 
</math>  
</math>  
]
]

Revision as of 13:30, 9 April 2013

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