A\kern{1.3em} \mathbf{A}
AT\kern{1.8em} \mathbf{A^{T}}
[123456]\begin{bmatrix}\color{black}1 & \color{black}2 \\\color{black}3 & \color{black}4 \\\color{black}5 & \color{black}6\end{bmatrix}
[135246]\begin{bmatrix}\color{white}1 & \color{white}3 & \color{white}5 \\\color{white}2 & \color{white}4 & \color{white}6\end{bmatrix}