一 计算过程:
输入: * ( x i , y i ) , T , L (x_i,y_i),T,L (xi,yi),T,L
1.初始化 f 0 f_0 f0
2.for t=1 to T do
2.1. 计算响应: y i ^ = − [ ∂ L ( y i , F ( x i ) ) ∂ F ( x i ) ] F ( x ) = F t − 1 ( x ) \hat{y_i}=-[\frac{\partial L(y_i,F(x_i))} {\partial F(x_i)}]_{F(x)=F_{t-1}(x)} yi^=−[∂F(xi)∂L(yi,F(xi))]F(x)=Ft−1(x) i=1,2,3…N
2.2. 学习第t棵树: w ∗ = a r g m i n w ∑ i = 1 N ( y i ^ − h t ( x i ; y ) ) 2 w^*=arg min_{w}\sum_{i=1}^N(\hat{y_i}-h_t(x_i;y))^2 w