短語詞組短語directional partial derivative 方向偏導數directional second derivative 方向性二階微分directional E derivative 方向導數Directional derivative and gradient 方向導數與梯度maximum directional derivative 極大方向微商;極大方向導數hadamard directional derivative hadamard 方向導數first directional derivative 一階方向導數Extended -directional derivative 延拓方向導數clarke general directional derivative clarke 廣義方向導數 返回 directional derivative