# Vector derivative partial to w

What's the derivative of E (below equation) partial to w: ( consider that w is vector)

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Just compute the derivative with respect to each component $w_j$. This will give you a vector which is your solution. – Matt L. Apr 12 '13 at 7:15

For each $k \in \{0,1,\ldots,M\}$:
$$\frac{\partial E}{\partial w_k} = \sum_{n=1}^N x_n^k\, x_n^i = 0$$