docs: protected PolynomialApproximation knnDistanceApproximation() {
      int p_max = 0;
      double[] b = null;
      for(int i = 0; i < getNumEntries(); i++) {
        MkAppEntry entry = getEntry(i);
        PolynomialApproximation approximation = entry.getKnnDistanceApproximation();
        if(b == null) {
          p_max = approximation.getPolynomialOrder();
          b = new double[p_max];
        }
        for(int p = 0; p < p_max; p++) {
          b[p] += approximation.getB(p);
        }
      }
  
      for(int p = 0; p < p_max; p++) {
        b[p] /= p_max;
      }
  
      if(LoggingConfiguration.DEBUG) {
        StringBuilder msg = new StringBuilder();
        msg.append("b " + FormatUtil.format(b, FormatUtil.NF4));
        Logger.getLogger(this.getClass().getName()).fine(msg.toString());
      }
  
      return new PolynomialApproximation(b);
    }