$$
      \begin{pmatrix}
      m_{1,1}  m_{1,2}  \cdots  m_{1,n} \\
      m_{2,1}  m_{2,2}  \cdots  m_{2,n} \\
      \vdots   \vdots   \ddots  \vdots  \\
      m_{n,1}  m_{n,2}  \cdots  m_{n,n}
      \end{pmatrix}
$$
