code: public double calcKMeansCosts(double[] center) {
  		assert (this.sumPoints.length == center.length);
  		return this.sumSquaredLength - 2
  				* Metric.dotProduct(this.sumPoints, center) + this.numPoints
  				* Metric.dotProduct(center);
  	}
docs: Calculates the k-means costs of the ClusteringFeature too a center.
  
  @param center
  the center too calculate the costs
  @return the costs