MATLAB常见的学习率下降策略

function learning_rate_decay(choose)
% Author: kailugaji 凯鲁嘎吉 - 博客园 http://www.cnblogs.com/kailugaji/
max_iter=1000;
y=zeros(1, max_iter);
t=1:max_iter;
if choose==1
    % cosine decay
    y(t)=0.5*(1+cos(pi*t/max_iter));
elseif choose==2
    % plot p>1:凹曲线, 0<p<1:凸曲线
    p=0.25;
    y(t)=(1-(t/max_iter)).^p;
elseif choose==3
    % inv
    gamma=0.99; p=0.25;
    y(t)=(1+gamma*t).^(-p);
elseif choose==4
    % exp
    gamma=0.99;
    y(t)=gamma.^t; 
elseif choose==5
    % sigmoid
    gamma=-0.01; stepsize=max_iter/2;
    y(t)=1./(1+exp(-gamma*(t-stepsize)));
else 
    disp('input error!');
end
%%
plot(t, y);
axis([1, max_iter, 0, 1]);
xlabel('iter');
ylabel('learning rate');