Tayler Series Approximation L(g)aroundθ=θ'can be approximated below L(0)≈L(a)+0-8)rg+E(0-g)H(g-g) Gradient g is a vector aL(0) g=7L(0) gi=001 L(0) Hessian H is a matrix 02 Hi=0010 、L(0')Tayler Series Approximation 𝐿 𝜽 ≈ 𝐿 𝜽 ′ + 𝜽 − 𝜽 ′ 𝑇𝒈 + 1 2 𝜽 − 𝜽 ′ 𝑇𝐻 𝜽 − 𝜽 ′ Gradient 𝒈 is a vector Hessian 𝐻 is a matrix 𝒈𝑖 = 𝜕𝐿 𝜽 ′ 𝜕𝜽𝑖 𝐻𝑖𝑗 = 𝜕 2 𝜕𝜽𝑖𝜕𝜽𝑗 𝐿 𝜽 ′ 𝒈 = 𝛻𝐿 𝜽 ′ 𝐿 𝜽 around 𝜽 = 𝜽 ′ can be approximated below 𝜽 ′ 𝜽 𝐿 𝜽