TDAT:     private float distortion(Vector[] currCentroids)  {
        // currently inefficient
        // cost could be calculated when determining nearest centroids
        float cost = 0.0f;
        int[] nearestCentroids = vectorsToNearestCentroid(currCentroids);
        for (int i = 0; i < vectorCount; ++i) {
            cost += vectors[i].distance(currCentroids[nearestCentroids[i]]);
        }
        return cost;
    }
 COM: <s> sum of distances to nearest centroid </s>