docs: protected double distanceHistogram(float histogramA[], float histogramB[]) {
  		double sumP = 0;
  		for( int i = 0; i < histogramA.length; i++ ) {
  			float q = histogramA[i];
  			float p = histogramB[i];
  			sumP += Math.abs(q-p);
  		}
  		return sumP;
  	}