docs: public float dotProduct(HashSparseVector sv) {
  		float v =0f;
  		if(sv.size() < data.size()){
  			TIntFloatIterator it = sv.data.iterator();			
  			while(it.hasNext()){
  				it.advance();
  				v += data.get(it.key())*it.value();
  			}
  		}else{
  			TIntFloatIterator it = data.iterator();			
  			while(it.hasNext()){
  				it.advance();
  				v += sv.data.get(it.key())*it.value();
  			}
  		}
  		return v;
  	}