protected void incrementalUpdateMean(double[] mean,V vec,int newsize,double op){
  if (newsize == 0) {
    return;
  }
  double[] delta=minusEquals(vec.toArray(),mean);
  plusTimesEquals(mean,delta,op / newsize);
}

protected void incrementalUpdateMean ( double [ ] mean , V vec , int newsize , double op ) { if ( newsize == 0 ) { return ; } double [ ] delta = minusEquals ( vec . toArray ( ) , mean ) ; plusTimesEquals ( mean , delta , op / newsize ) ; }
compute an incremental update for the mean .
