Originally posted by: Lessi

I have write some lines of code to test if I understand the callback:

ILOINCUMBENTCALLBACK0(feasibilityCheck)

{

cout << "we are in an incumbent callback!!!" << endl;


int newIncumbent = this->hasIncumbent();


if (newIncumbent)

{

cout << "we have an incumbent solution" << endl;

}


}

we have an incumbent solution

      Nodes                                         Cuts/
   Node  Left     Objective  IInf  Best Integer    Best Bound    ItCnt     Gap         Variable B NodeID Parent  Depth

      0     0      127.8125     5                    127.8125       20         
we are in an incumbent callback!!!
*     0+    0                          119.0000      127.8125             7.41%   => I think this is a solution (an incumbent)
      0     0      126.0199    15      119.0000       Cuts: 3       28    5.90%
      0     0      124.9401    18      119.0000      Cuts: 19       39    4.99%
      0     0      123.9318    17      119.0000      Cuts: 27       49    4.14%
      0     0      123.7923    15      119.0000   ZeroHalf: 1       52    4.03%
      0     0      123.6677    18      119.0000   ZeroHalf: 2       54    3.92%
we are in an incumbent callback!!!
we have an incumbent solution
*     0+    0                          120.0000      123.6677             3.06%
      0     0      123.6397    21      120.0000       Cuts: 6       56    3.03%
      0     0      123.5945    18      120.0000   ZeroHalf: 1       58    3.00%
      0     0      123.5779    22      120.0000       Cuts: 9       61    2.98%
      0     0      123.4845    22      120.0000   ZeroHalf: 3       65    2.90%
      0     0      123.4705    21      120.0000      Cuts: 11       69    2.89%
      0     2      123.4705    21      120.0000      123.4704       69    2.89%                        0             0
Elapsed time = 0.07 sec. (33.42 ticks, tree = 0.00 MB, solutions = 2)

Originally posted by: Lessi

Another question: when I add codes to extract the value of the incumbent solution, it throws an exception. Your suggestion is valueable!

IloBoolVarArray y(env, 0); //this is the declaration of the y variables

...

ILOINCUMBENTCALLBACK0(feasibilityCheck)

{

cout << "we are in an incumbent callback!!!" << endl;

 

int newIncumbent = this->hasIncumbent();

 

if (newIncumbent)

{

cout << "we have an incumbent solution" << endl;

//those two lines of code throw an exception - I also try with IloNumArray y_val(env,"Number of variables to extract"); but it does not solve the issue

IloNumArray y_val(env); 

this->getValues(y_val, y);

}

 

}

 I put the code in a try/catch, and it shows: Error: IloExtractable 2 IloNumVarI has not been extracted by IloAlgorithm 

Thanks,

-----------------------

Solved: I use model.add method to explicitly add the variables to the model.