+ // N points
+ // K clusters
+ // dist(n,k) distance of samples n to cluster k
+ //
+ // We want to optimize the
+ //
+ // \gamma(n,k) is the association of point n to cluster k
+ //
+ // to minimize
+ //
+ // \sum_{n,k} \gamma(n,k) dist(n,k)
+ //
+ // under
+ //
+ // (A) \forall n, k, \gamma(n, k) >= 0
+ // (B) \forall n, \sum_k \gamma(n,k) = 1
+ // (C) \forall k, \sum_n \gamma(n,k) = N/K
+