public double addAndEvaluate(Recommendation<U,I> recommendation){
  double v=metric.evaluate(recommendation);
  if (!ignoreNaN || !Double.isNaN(v)) {
    sum+=v;
    if (!allUsers) {
      numUsers++;
    }
  }
  return v;
}

public double addAndEvaluate ( Recommendation < U , I > recommendation ) { double v = metric . evaluate ( recommendation ) ; if ( ! ignoreNaN || ! Double . isNaN ( v ) ) { sum += v ; if ( ! allUsers ) { numUsers ++ ; } } return v ; }
adds the recommendation metric to the average and returns the user value .
