Backpropagation in equations II

• If j is a node in a hidden layer, and if there are k nodes 1, 2, ..., k, that receive a connection from j, the error ?j is:

• ?j = (w1j ?1 + w2j ?1 + ... + wkj?k) aj (aj -1)

• where the weights w1j , w2j , ..., wkj belong to the connections from hidden node j to nodes 1, 2, ..., k.