ord">if</span> nargin &lt;4
    Amin = zeros(1,n);
<span class="keyword">else</span>
    <span class="keyword">if</span> min(size(Amin)) ~=1
        error(<span class="string">'Amin should be a vector'</span>);
    <span class="keyword">end</span>
    <span class="keyword">if</span> max(size(Amin)) ~= n
        error(<span class="string">'Amin should have the same length as the input graphs'</span>);
    <span class="keyword">end</span>
    <span class="keyword">if</span> size(Amin,1)~=1
        Amin = Amin