vector derivative

[Math] Commonly used Vector derivatives.

많이 사용되는 vector 도함수들을 정리함. Numeartor Layout 과 Denominator Layout을 구분하여 살펴야 함. $$f(\textbf{x})$$ $$\frac{\partial f(\textbf{x})}{\partial \textbf{x}}$$ Convention $$f(x)$$ $$\frac{df(x)}{dx}$$ $$\textbf{x}^T \textbf{b}$$ $$\textbf{b}^T$$ Numerator Layout $$bx$$ $$b$$ $$\textbf{b}^T \textbf{x}$$ $$\textbf{b}^T$$ Numerator Layout $$bx$$ $$b$$ $\textbf{b}\cdot \textbf{x}$ or $\textbf{x}\cdot \textbf{..