In this example, the population clusters have equal covariance matrices. If the within-cluster covariances are known, the data can be transformed to make the clusters spherical so that any of the ...

For unequal covariance matrices or radically nonnormal distributions, the best approach to cluster analysis is through nonparametric density estimation, as in density linkage. The next example ...

Fig 1: (a) Concept of cluster quantum microcombs. (b) Quadrature noise variances of EPR pairs relative to vacuum shot noise. (c) Covariance matrix of a 1D cluster state. (d) Covariance matrix of a ...