docs: private double preNormMBR(SpatialComparable mbr, final int start, final int end) {
      double agg = 0.;
      for(int d = start; d < end; d++) {
        double delta = mbr.getMin(d);
        delta = delta >= 0 ? delta : -mbr.getMax(d);
        if(delta > 0.) {
          agg += FastMath.pow(delta, p);
        }
      }
      return agg;
    }