docs: public void printGridList()
  	{
  		System.out.println("Grid List. Size "+this.grid_list.size()+".");
  		for (Map.Entry<DensityGrid, CharacteristicVector> grid : grid_list.entrySet())
  		{
  			DensityGrid dg = grid.getKey();
  			CharacteristicVector cv = grid.getValue();
  			
  			if (cv.getAttribute() != SPARSE)
  			{
  				double dtf = densityThresholdFunction(cv.getUpdateTime(), this.cl, this.getDecayFactor(), this.N);
  				System.out.println(dg.toString()+" "+cv.toString()+" // Density Threshold Function = "+dtf);
  			}
  		}
  	}