A matrix is a rectangular array of numbers: \begin{equation} [A] = \begin{bmatrix} 1 & 8 & 17.3 \\ 7 & 2.1 & 5.2 \end{bmatrix} \end{equation} It is no different than just a table of entries. A matrix is typically denoted with bracket $[A]$ or a boldface letter $\mathbf{A}$. Entries in a matrix can be shorthanded …