Logistic回归为什么不用均方误差 MSE（square error）逻辑回归：输出 y^=σ(z)=11+e−z\hat y=\sigma(z)=\frac{1}{1+e^{-z}}y^=σ(z)=1+e−z1，KaTeX parse error: Can't use function '\(' in math mode at position 1: \̲(̲z=wx+b\)，y^∈(0,1)\hat y\in(0,1)y^∈(0,1)，标签 y∈{0,1}y\in\{0,1\}y∈{0,1}。