[Coin-discuss] How to get dual values.

[Heesu Hwang]

Hi, all
I am solving maximization problem, so my objective has all negative
coefficients.
Also, I want to generate variables using dual values, thus I've tried to get
the dual values in

double DCG_lp::compute_lower_bound(const double old_lower_bound,
				   const BCP_lp_result& lpres,
				   const BCP_vec<BCP_var*>& vars,
				   const BCP_vec<BCP_cut*>& cuts){

	cout << "# of constraints: " << cuts.size() << endl;
	int cs = cuts.size();

	const double * pitmp = lpres.pi();
	for(int i=0; i<cs; i++)
		cout << "(" << i+1 << ")" << pitmp[i] << " ";
	cout << endl;

}

However, result was strange, i.e., I can't get negative dual values, but all
0's.

LP: *** Starting iteration 1 ***
DCG_lp::modify_lp_parameters
LP   node   written   in   file   lpnode.mps
LP:   Matrix size: 11 vars x 30 cuts
LP:   Solution value: -1022840.4200 / 2 , 0
 LP: Default display_lp_solution() executed.
  LP : Displaying LP solution (RelaxedSolution) :
  LP : Displaying solution :
  Algo  var (internal index:      1                    ) at 1.0000
  Algo  var (internal index:      2                    ) at 1.0000
  Algo  var (internal index:      3                    ) at 1.0000
  Algo  var (internal index:      4                    ) at 1.0000
  Algo  var (internal index:      5                    ) at 1.0000
  Algo  var (internal index:      6                    ) at 1.0000
  Algo  var (internal index:      7                    ) at 1.0000
  Algo  var (internal index:      8                    ) at 1.0000
  Algo  var (internal index:      9                    ) at 1.0000
  Algo  var (internal index:     10                    ) at 1.0000
.........................................
# of constraints: 30
(1)0 (2)0 (3)0 (4)0 (5)0 (6)0 (7)0 (8)0 (9)0 (10)0 (11)0 (12)0 (13)0 (14)0
(15)0 (16)0 (17)0 (18)0 (19)0 (20)0 (21)0 (22)0 (23)0 (24)0 (25)0 (26)0
(27)0 (28)0 (29)0 (30)0

Help me to get dual values.

Thanks in advance,

Peter.