function clusterIdx = mySpectralClustering (anAffinityMat, k)
%Implementation of spectral clustering
%   Usage clusterIdx = mySpectralClustering (anAffinityMat, k), where:
%       Inputs
%       - anAffinityMat is a rectagular, symmetrical affinity matrix
%           representation of an image
%       - k is the desired number of clusters
%       Output
%       - clusterIdx is a vector storing the cluster Id of each node

    L = diag(sum(anAffinityMat, 2)) - anAffinityMat;
    [eigenvectorsMatrix, ~] = eigs(L, k, 'sm');
    clusterIdx = kmeans(eigenvectorsMatrix, k);
end