Machine Learning - Coursera week5 cost function and backpropagation 2

1. 回顧cost function cost function for a neural network is: J(Θ)=−1m∑t=1m∑k=1K[y(t)k log(hΘ(x(t)))k+(1−y(t)k) log(1−hΘ(x(t))k)]+λ2m∑l=1L−1∑i=1sl∑j=1sl+1(Θ(l)j,i)2 J ( Θ ) = − 1 m ∑ t = 1 m ∑ k = 1 K [ y

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