docs: protected double[][] splitCentroid(Cluster<? extends MeanModel> parentCluster, Relation<V> relation) {
      double[] parentCentroid = parentCluster.getModel().getMean();
  
      // Compute size of cluster/region
      double radius = 0.;
      for(DBIDIter it = parentCluster.getIDs().iter(); it.valid(); it.advance()) {
        double d = getDistanceFunction().distance(relation.get(it), DoubleVector.wrap(parentCentroid));
        radius = (d > radius) ? d : radius;
      }
  
      // Choose random vector
      Random random = rnd.getSingleThreadedRandom();
      final int dim = RelationUtil.dimensionality(relation);
      double[] randomVector = normalize(MathUtil.randomDoubleArray(dim, random));
      timesEquals(randomVector, (.4 + random.nextDouble() * .5) * radius);
  
      // Get the new centroids
      for(int d = 0; d < dim; d++) {
        double a = parentCentroid[d], b = randomVector[d];
        parentCentroid[d] = a - b;
        randomVector[d] = a + b;
      }
      return new double[][] { parentCentroid, randomVector };
    }