docs: public double calcKMeansCosts(double[] center, double[] point) {
  		assert (this.sumPoints.length == center.length &&
  				this.sumPoints.length == point.length);
  		return (this.sumSquaredLength + Metric.distanceSquared(point)) - 2
  				* Metric.dotProductWithAddition(this.sumPoints, point, center)
  				+ (this.numPoints + 1) * Metric.dotProduct(center);
  	}