But when you are doing a cluster analysis, you do not know what the true clusters are, so you cannot calculate the within-cluster covariance matrix. Nevertheless, it is sometimes possible to estimate ...

Nonconvex Clusters . If the population clusters have very different covariance matrices, using PROC ACECLUS is of no avail. Although methods exist for estimating multinormal clusters with unequal ...

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 ...