\begin{definition}[Definition:Column Matrix]
A '''column matrix''' is an $m \times 1$ matrix:
:$\mathbf C = \begin {bmatrix} c_{1 1} \\ c_{2 1} \\ \vdots \\ c_{m 1} \end {bmatrix}$
That is, it is a matrix with only one column.
\end{definition}