private void recomputeCentersFast(Instances centers, int [][] instOfCentIndexes,
protected void recomputeCentersFast(Instances centers, int[][] instOfCentIndexes,
  private void recomputeCentersFast(Instances centers,          				    int [][] instOfCentIndexes, 				    Instances model   				    ) {    for (int i = 0; i < centers.numInstances(); i++) {      double val;      for (int j = 0; j < model.numAttributes(); j++) {	val = meanOrMode(m_Instances, instOfCentIndexes[i], j);	centers.instance(i).setValue(j, val);      }    }  }