docs: protected LinearScale computeScale(ClusterOrder order) {
      DoubleMinMax range = new DoubleMinMax();
      // calculate range
      for(DBIDIter it = order.iter(); it.valid(); it.advance()) {
        final double reach = co.getReachability(it);
        if(reach < Double.POSITIVE_INFINITY) {
          range.put(reach);
        }
      }
      // Ensure we have a valid range
      if(!range.isValid()) {
        range.put(0.0);
        range.put(1.0);
      }
      return new LinearScale(range.getMin(), range.getMax());
    }