E_{ij} : = \begin{array}{*{20}c}
 1 \\
 \vdots \\
 i \\
 \vdots \\
 m \\

 \end{array} \mathop {\left[ {\begin{array}{*{20}c}
 0 & \cdots & 0 & \cdots & 0 \\
 \vdots & \ddots & \vdots & {\mathinner{\mkern2mu\raise1pt\hbox{.}\mkern2mu
 \raise4pt\hbox{.}\mkern2mu\raise7pt\hbox{.}\mkern1mu}} & \vdots \\
 0 & \cdots & 1 & \cdots & 0 \\
 \vdots & {\mathinner{\mkern2mu\raise1pt\hbox{.}\mkern2mu
 \raise4pt\hbox{.}\mkern2mu\raise7pt\hbox{.}\mkern1mu}} & \vdots & \ddots & \vdots \\
 0 & \cdots & 0 & \cdots & 0 \\

 \end{array} } \right]}\limits^{\begin{array}{*{20}c}
 1 & \cdots & j & \cdots & n \\

 \end{array} }