模式识别-Ch2-高斯下判别函数多元正态分布: x = [ x 1 , x 2 , … , x d ] T ∈ R d , μ = [ μ 1 , μ 2 , … , μ d ] T ∈ R d \mathbf{x} = [x_1, x_2, \ldots, x_d]^T \in \mathbb{R}^d,\ \boldsymbol{\mu} = [\mu_1, \mu_2, \ldots, \mu_d]^T \in \mathbb{R}^d x=[x1,x2,…,xd]T∈Rd, μ=[μ1,μ2,…,μd]T∈Rd