【2022-02-08】二分分类及Logistic回归函数笔记

2022-02-08 本文已影响0人坐了整个春夏秋冬

$\hat{y} = sigmoid(w^Tx+b)$

$w=nx$

$sigmoid(z) = \frac{1}{1+e^{-z}}$

$z = w^Tx + b$

$z^{(i)} = w^Tx^{(i)} + b$

$L(\hat{y},y)=-(ylog\hat{y}+(1-y)log(1-\hat{y}))$

$J(w,b) = \frac{1}{m}\sum\limits_{i=1}^{m}L(\hat{y}^{(i)},y^{(i)})$

$J(w,b) = -\frac{1}{m} \sum\limits_{i=1}^{m}[y^ilog\hat{y}^i+(1-y^i)log(1-\hat{y}^i)]$

markdown注释
分号 \frac{分子}{分母} 
求和 \sum\limits_{i=1}^{m}
帽子 \hat{变量}