Basics
0.1 Basic Content $$ \begin{align} (\boldsymbol{AB})^{-1} &= \boldsymbol{B}^{-1}\boldsymbol{A}^{-1} \cr (\boldsymbol{ABC\cdots})^{-1} &= \cdots\boldsymbol{C}^{-1}\boldsymbol{B}^{-1}\boldsymbol{A}^{-1} \cr (\boldsymbol{A}^\top)^{-1} &= (A^{-1})^\top \cr (\boldsymbol{A} + \boldsymbol{B})^\top &= \boldsymbol{A}^\top + \boldsymbol{B}^\top \cr (\boldsymbol{AB})^\top &= \boldsymbol{B}^\top\boldsymbol{A}^\top \cr (\boldsymbol{ABC\cdots})^\top &= \cdots\boldsymbol{C}^\top\boldsymbol{B}^\top\boldsymbol{A}^\top \cr (\boldsymbol{A}^{H})^{-1} &= (\boldsymbol{A}^{-1})^{H} \cr (\boldsymbol{A} + \boldsymbol{B})^H &= \boldsymbol{A}^H + \boldsymbol{B}^H \cr (\boldsymbol{AB})^H &= \boldsymbol{B}^H\boldsymbol{A}^H \cr (\boldsymbol{ABC\cdots})^H &= \cdots\boldsymbol{C}^H\boldsymbol{B}^H\boldsymbol{A}^H \end{align} $$
0.2 Trace $$ \begin{align} \text{TR}(\boldsymbol{A}) &= \sum_{i}A_{ii} \cr \text{TR}(\boldsymbol{A}) &= \sum_{i}\lambda_{i}, \quad \lambda_{i}=\text{eig}(\boldsymbol{A})_{i} \cr \text{TR}(\boldsymbol{A}) &= \text{TR}(\boldsymbol{A}^\top) \cr \text{TR}(\boldsymbol{AB}) &= \text{TR}(\boldsymbol{BA}) \cr \text{TR}(\boldsymbol{A+B}) &= \text{TR}(\boldsymbol{A}) + \text{TR}(\boldsymbol{B}) \cr \text{TR}(\boldsymbol{ABC}) &= \text{TR}(\boldsymbol{BCA}) = \text{TR}(\boldsymbol{CAB}) \cr \boldsymbol{a}^\top\boldsymbol{a} &= \text{Tr}(\boldsymbol{aa}^\top) \end{align} $$