int testGurobi(){
	int nCustomers = 5;
	GRBEnv* env = 0;
	
	GRBVar **y =0;
	GRBVar ***x=0;
	GRBVar ***z=0;
	double relaxedVal = 0.0;


	try
	{


		int nDays = 3;
		int nSchedules = 7;
		int Capacity = 289;
		int dailyDemand[6] = {0,65,35,58,24,11};
		
	
		double holdRate[6] = {0,0.23,0.32,0.33,0.23,0.18	};
		double holdRate_depot[6] = {0,0.23,0.32,0.33,0.23,0.18};
			
		
		double arcCost[7][7] = {
			{0,		84,		348,	17,		202,	289,	 0},	
			{84,	0,		264,	101,	213,	226,	 84},	
			{348,	264,	0,		365,	367,	238,	 348},
			{17,	101,	365,	0,		207,	301,	 17	},
			{202,	213,	367,	207,	0,		430,	 202},
			{289,	226,	238,	301,	430,	0,		289	},
			{0,		84,		348,	17,		202,	289,	 0	},
		};


		int *maxSchedule;
		maxSchedule = new int[nSchedules];
		int schedule[3][7] = {
			
			{ 1, 1, 0, 1, 1, 0, 0 },
			{ 1, 1, 1, 0, 0, 1, 0  },
			{ 1, 0, 1, 1, 0, 0, 1  }
		};

		int scheduleAmount[3][7] ={
			
			{ 1, 2, 0, 1, 3, 0, 0 },
			{ 1, 1, 2, 0, 0, 3, 0  },
			{ 1, 0, 1, 2, 0, 0, 3  }
		};
		
		//find the max unit in the schedule column
		for(int j = 0 ; j<nSchedules	; ++j)
		{
			int maxSche =0;
			for(int i = 0 ; i <nDays ; ++i)
			{
				if ( maxSche < scheduleAmount[i][j])
					maxSche = scheduleAmount[i][j];

			}
			maxSchedule[j] = maxSche;
		}

		//calculate holding cost
		double *temp1;
		double *temp2;
		double **holdingCost;
		temp1 = new double[nSchedules];
		temp2 = new double[nSchedules];
		for(int i =0 ; i< nSchedules;i++)
		{
			temp1[i] = 0;
			temp2[i]=0;
		}

		holdingCost = new double * [nCustomers+1];
		for(int i =0 ; i< nCustomers+1;i++)
			holdingCost[i] = new double [nSchedules];

		for (int i= 1; i <nCustomers+1;i++)
		{
			for(int j=0; j<nSchedules;j++)
			{
				for(int day =0; day<nDays;day++)
				{
					temp1[j]+=scheduleAmount[day][j]*(scheduleAmount[day][j]-1)/2;
					//temp2[j] = 0;
					if(scheduleAmount[day][j] >= temp2[j])
						temp2[j] = scheduleAmount[day][j];

				}
				holdingCost[i][j] = holdRate[i]*dailyDemand[i]*temp1[j]+holdRate_depot[i]*dailyDemand[i]*(nDays*(temp2[j]-1)-temp1[j]);
				//cout<< "\n"<< i << " - "  << j+1 << holdingCost[i][j] ;
			}
		}

		// Model
		env = new GRBEnv();
		//gMainGRBModel = new GRBModel(*env);
		//GRBModel model = *gMainGRBModel;
		GRBModel model = GRBModel(*env);
		model.set(GRB_StringAttr_ModelName, "loadrelax");


		//z variable
		z = new GRBVar ** [nCustomers+2];
		for (int i = 0; i < nCustomers+2; i++) {
			z[i] = new GRBVar *[nCustomers +2];

			for (int j = 0; j < nCustomers+2; j++) {
				z[i][j] = model.addVars(nDays);

				for (int t = 0; t < nDays; t++) {
					string s = "z_" + itos(i) + "_"+ itos(j) +  "_"+itos(t);
					z[i][j][t] = model.addVar(0.0, Capacity, 0.0, GRB_CONTINUOUS, s);

				}
			}
		}

		//y variable

		y = new GRBVar *[nCustomers+1];
		for(int i =0; i < nCustomers+1;i++)
		{
			y[i] = model.addVars(nSchedules);
			//yCt++;
			//model.update();
			for(int s =0;s< nSchedules;s++)

				y[i][s]=model.addVar(0.0,1.0,0.0,GRB_BINARY,"y_"+itos(i)+ "_" + itos(s));
					//y[i][s]=model.addVar(0.0,1.0,0.0,GRB_CONTINUOUS,"y_var_"+itos(i)+ "_"+itos(s));
		}

		//x variable
		x = new GRBVar ** [nCustomers+2];
		for (int i = 0; i < nCustomers+2; i++) {
			x[i] = new GRBVar *[nCustomers +2];
			
			for (int j = 0; j < nCustomers+2; j++) {
				if( j > i && !(j==nCustomers+1 && i ==0))
				{
				x[i][j] = model.addVars(nDays);

				for (int t = 0; t < nDays; t++) {
					string s = "x_" + itos(i) +  "_"+itos(j) +  "_"+itos(t);
					//x[i][j][t] = model.addVar(0.0, 1.0, 0.0, GRB_CONTINUOUS, s);
					x[i][j][t] = model.addVar(0.0, 1.0, 0.0, GRB_BINARY, s);
				}
			}
		}
		}

		// Update model to integrate new variables
		model.update();
		//difference b/n the sum of the commodity flow variables associated with arcs entering and leaving each vertex i is twice the demand of i.
		for(int i=1;i< nCustomers+1;++i)
		{
			for(int t=0;t < nDays;t++)
			{


				GRBLinExpr ntot1 = 0;
				for(int j=0;j< nCustomers+2;++j)
				{					
					if(i!=j)
					{
						ntot1 += (z[j][i][t] - z[i][j][t]);

					}

				}

				GRBLinExpr ntot2 = 0;
				for(int s=0; s<nSchedules; s++)
					ntot2 += scheduleAmount[t][s] * y[i][s];

				string s = "CF_" + itos(i) + "_" + itos(t);
				model.addConstr(ntot1 == 2*dailyDemand[i] * ntot2, s);

			}

		}

		////constraint 2
		//

		for (int i = 0; i < nCustomers+1; ++i)
		{

			for (int j=1;j< nCustomers+2;++j)
			{	

				for(int t = 0; t < nDays; ++t)
				{
					//if(!((i==j) || (i==0 && j == nCustomers+1) || ( i == nCustomers+1 && j ==0) || i>j)  )
						if( j > i && !(j==nCustomers+1 && i ==0))
					{
						string s = "Constraint2_" + itos(i) + "_" + itos(j) + "_" + itos(t);
						model.addConstr(z[i][j][t] + z[j][i][t] == Capacity*(x[i][j][t]), s);

					}

				}


			}

		}

	

		////constraint 3

		for  (int t=0; t < nDays; ++t)
		{
			GRBLinExpr ntot3 = 0;
			for(int i = 1; i < nCustomers + 1 ; ++i)
			{
				for(int s = 0 ;s<nSchedules;++s )
				{
					ntot3 += dailyDemand[i]*scheduleAmount[t][s] * y[i][s];

				}
			}

			GRBLinExpr ntot4 = 0;
			for(int j = 1; j < nCustomers + 1 ; ++j)
			{
				ntot4 += z[0][j][t];
			}

			model.addConstr(ntot4 == ntot3);


		}

		////constraint 4


		for  (int t=0; t < nDays; ++t)
		{
			GRBLinExpr ntot5 = 0;
			for(int i = 1; i < nCustomers + 1 ; ++i)
			{
				for(int s = 0 ;s<nSchedules;++s )
				{
					ntot5 += dailyDemand[i]*scheduleAmount[t][s] * y[i][s];

				}
			}

			GRBLinExpr ntot6 = 0;GRBLinExpr ntot7 = 0;
			for(int j = 1; j < nCustomers + 1 ; ++j)
			{
				ntot6 += z[j][0][t];
				ntot7 += z[nCustomers+1][j][t];
			}

			model.addConstr((ntot7 - ntot6) == ntot5);


		}

		
		//constraint 6 

		for (int i = 1; i < nCustomers+1; ++i)
		{

			for (int t = 0; t < nDays; ++t)
			{	
				GRBLinExpr ntot1 = 0;GRBLinExpr ntot2 = 0;
				GRBLinExpr ntot3 = 0;
				for(int j=0;j< nCustomers+2;++j)
				{
					
					if( j > i && !(j==nCustomers+1 && i ==0))
						ntot1 += x[i][j][t];
					else if ( j<i && !(j==nCustomers+1 && i ==0))
						ntot3 += x[j][i][t];
				}
				for(int s =0;s<nSchedules;++s)
					ntot2+=schedule[t][s]*y[i][s];

				string s = "ScheduleArc1_" + itos(i) + "_" + itos(t);
				model.addConstr(ntot1 + ntot3 == 2*ntot2, s);
			}
		}

		
		////ScheduleConstraint

		for(int i=1;i< nCustomers+1;++i)
		{
			GRBLinExpr ntot9 = 0;
			for(int s=0; s<nSchedules; s++)
				ntot9 += y[i][s];

			string str = "ScheduleConstraint_" + itos(i);
			model.addConstr(ntot9 == 1 , str);	
		}

		


		//objective
		GRBLinExpr obj = 0;
		for(int i=0;i< nCustomers+1;++i)
		{
			for(int j=1;j< nCustomers+2;++j)
			{
				for(int t=0;t<nDays;t++)
				{
					//if(!((i==j) || (i==0 && j == nCustomers+1) || ( i == nCustomers+1) ) ) // self loop, 0 to n+1 and n+1 to 0 edges are removed.
						if(j>i && !(j==nCustomers+1 && i ==0))
							obj += arcCost[i][j]*x[i][j][t];

				}
			}
		}
		for(int i = 1; i < nCustomers+1 ; ++i)
		{
			for(int s=0 ; s < nSchedules ; ++s)
			{
				obj += holdingCost[i][s] * y[i][s];
			}
		}
		model.setObjective(obj,GRB_MINIMIZE);
		model.optimize();
		

			int status = model.get(GRB_IntAttr_Status);
			cout<<status;
				
	}
	catch (GRBException e)
	{
		cout << "error code = " << e.getErrorCode() << endl;
		cout << e.getMessage() << endl;
	}
	catch (...)
	{
		cout << "exception during optimization" << endl;
	}
	

	return 0;}