df.m

BP神经网络

function dff=df(net)
%calculate the derivation of sigmoid function
a=1.716;
b=2/3;
len=size(net,1);
for i=1:len
    dff(i,:)=(2*a*b*exp(-b*net(i,:)))/((1+exp(-b*net(i,:)))^2);
end