{bmatrix} \! , \]</span> with a padded value at the end
to guarantee that <span class="math display">\[ u(A)[n+1] - u(A)[n] \]</span> is the number of non-zero
elements in row <span class="math inline">\(n\)</span> of the matrix (here <span class="math inline">\(2\)</span>, <span class="math inline">\(0\)</span>, <span class="math inline">\(1\)</span>, and <span class="math inline">\(3\)</span>). Note
that because the second row has no non-zero elements both the second
and third elements of <span class="mat