原文地址 Why are deep neural networks hard to train? 前一章有介绍，任意函数都可以通过2层神经网络来求解，但是并不是说任何问题都用两层就好了。因为“可以做到”并不一定是“最好的”。 作者的观点是，当使用2层神经网络来解决问题的时候，需要的神经元的数量可能是多层网络的指数倍，设计的困难程度也比多层复杂得多。 Deep circuits thu...
Neural Networks And Deep Learning Chap3
原文地址 a better choice of cost function, known as the cross-entropy cost function four so-called “regularization” methods (L1 and L2 regularization, dropout, and artificial expansion of the tra...
Neural Networks And Deep Learning Chap2
原文地址 Warm up: a fast matrix-based approach to computing the output from a neural network The two assumptions we need about the cost function 两个假设： \[C=\frac{1}{2n}\sum_x \left \| y(x)-a^{L}(...
Neural Networks And Deep Learning Chap1
原文地址 perceptrons（感知器） 1950s-1960s by scientist Frank Rosenblatt 数学模型： 所有权重参数为w1,w2…，threshold threshold，Dropping the threshold means you’re more willing to go to the festival. 与权重b是同一种意思，...