Adjacency Matrix/Examples/Loop-Digraph

Example of Adjacency Matrix
The adjacency matrix for a loop-digraph is not only not symmetrical about the main diagonal, it also has non-zero elements on that main diagonal:

$\qquad \begin{pmatrix} 1 & 1 & 0 & 1 \\ 0 & 0 & 0 & 1 \\ 0 & 0 & 0 & 0 \\ 1 & 0 & 1 & 0 \\ \end{pmatrix}$