Fuzzy clustering using scatter matrices

Starting from the well-known fuzzy k-means method, which was mainly intended for spherical clusters, several methods are considered which incorporate cluster-specific scatter matrices. This enables them to describe elliptical clusters with different orientation. The distinction between these methods lies in the way they deal with clusters of different volume, cardinality, and density. Some industrial examples show that different applications may lead to different goals and preferences, which affect the choice of the clustering method.