3.7 激活函数的导数(Derivatives of activation functions )
sigmoid函数的导数:
g(z)=1+e(−z)1 g′(z)=dzdg(z)=g(z)(1−g(z))=a(1−a) tanh函数的导数:
g(z)=e(z)+e(−z)e(z)−e(−z) g′(z)=dzdg(z)=1−(g(z))2=1−a2 ReLU函数的导数:
g(z)=max(0,z) x={01if z<0if z≥0 LeakyReLU函数:
g(z)=max(0.01z,z) g′(z)={0.011if z<0if z≥0