BP反向传播

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This is an example link.

$$\frac{\partial {L_d}}{\partial {w^{(1)}_{j}}}=\frac{\partial {L_d}}{\partial {out_{j}}} \frac{\partial {out_{j}}}{\partial {net_{j}}} \frac{\partial {net_{j}}}{\partial {w^{(1)}_{j}}}$$

设

$$\delta _{j}^{(1)} = \frac{\partial {L_d}}{\partial {out_{j}}} \frac{\partial {out_{j}}}{\partial {net_{j}}}$$