//.x C:/Code/MultiTreeDemo/ForumEntryTestFullWriteHasFriends.cpp
{
	string base_data_dir = "C:/Code/MultiTreeDemo/";	
	string file_name = base_data_dir + "FriendForestTest_main.root";
	string friend_file_name = base_data_dir + "FriendForestTest_friend.root";	
	bool verbose_output = true;
	TFile * file = 0;
	TFile * friend_file = 0;
	int n_branches = 53;
	int n_fr_branches = 3;
	int n_total_branches = n_branches + n_fr_branches;
	
	/////Start of File Write Block
	//In this block we create the base file and the friend file
 
	int n_trees = 10708;//Total number of trees.
	int n_entries_per_tree = 155;//number of branches per tree. Minimum is 1		
	file= new TFile(file_name.c_str(),"RECREATE");
	friend_file= new TFile(friend_file_name.c_str(),"RECREATE");
	TRandom r;
	vector<double> data, fr_data;//create data buffers
	data.resize(n_branches);
	fr_data.resize(n_fr_branches);
	double * data_root = &(data[0]);
	double * fr_data_root = &(fr_data[0]);				
	int j = 0, k =0;
	int write_frequency = 1000;
	try
	{	
		for(k=1;k<=n_trees;k++)
		{					
			stringstream tree_name_builder;
			tree_name_builder<<"Tree_"<<k;		
			string tree_name = tree_name_builder.str();				
			file->cd();//CD to the main file
			TTree * tree = new TTree(tree_name.c_str(), "Main tree");//create main tree 				
			for(int l=0;l<data.size();l++)
			{					 
				stringstream branch_name_builder;
				branch_name_builder<<"Branch_"<<l;
				tree->Branch(branch_name_builder.str().c_str(), l + data_root , "DataValue/D");			
			}
			
			TTree * friend_tree = NULL;	//create friend tree
			friend_file->cd();
			friend_tree = new TTree(tree_name.c_str(),"Computed friend file");//create friend tree	
			friend_tree->Branch("GeomMean", 0 + fr_data_root , "DataValue/D");//add friend tree	branches
			friend_tree->Branch("LocMin", 1 + fr_data_root , "DataValue/D");
			friend_tree->Branch("LocMax", 2 + fr_data_root , "DataValue/D");
			TFriendElement * elm = tree->AddFriend(friend_tree ,"Computed tree"); //Make friends
							
			j =0;

			for(j=1;j<=n_entries_per_tree;j++)
			{					 
				r.RndmArray(data.size(),data_root );//fill vector with random data					 
				fr_data[0] = TMath::GeomMean(data.size(),data_root );//calculate some values and store them
				fr_data[1] = TMath::LocMin(data.size(),data_root );
				fr_data[2] = TMath::LocMax(data.size(),data_root );		
				tree->Fill();
				friend_tree->Fill();
			}				 
			if(k%write_frequency ==0)//write every 1000 entries
			{
				int nbytes = file->Write();	
				cout <<"File Write out ["<<k<<"]["<<j<<"] == "<<nbytes<<endl;	
				nbytes = friend_file->Write();		
				cout <<"Friend File Write out ["<<k<<"]["<<j<<"] == "<<nbytes<<endl;	
				//refresh file pointers. This clears the buffers thus allowing the iteration to continue
				file->Flush();
				file->Close();	
				delete file;
				file= new TFile(file_name.c_str(),"UPDATE");
				
				friend_file->Flush();
				friend_file->Close();		
				delete friend_file;				
				friend_file= new TFile(friend_file_name.c_str(),"UPDATE");								
				
			}
			
		}
	}		
	catch()
	{
		cout <<"Exception["<<k<<"]["<<j<<"] == "<<endl;			
	}	
	//friend_file->Write();
	friend_file->Flush();
	friend_file->Close();		
	file->Write();			
	file->Flush();//close file
	file->Close();				

	/////End of File Write Block	
}