Now I have a linear programming model, I have tried to formulate this model with or-tools, and then solve it with the GLOP but failed.

After reaching the 15-minute time limit, the status of GLOP is reported as NOT_SOLVED and the log output is listed below. I would like to ask, during the GLOP solving process, if the Primal Objective and Dual Objective are already very close to each other, can the results be outputted by setting appropriate parameters?

Dual optimization phase, iteration # 7025615, objective = 8.254744303120898E+11 [check]
Dual optimization phase, iteration # 7025616, objective = 8.254744303120903E+11 [check]
Dual optimization phase, iteration # 7025617, objective = 8.254744303120898E+11 [check]
Current status: DUAL_FEASIBLE
Primal infeasibility (bounds) = 1.54972e-06
Primal residual |A.x - b| = 5.36442e-07
Dual infeasibility (reduced costs) = 0
Dual residual |c_B - y.B| = 7.10543e-15

Final unscaled solution:
Primal objective (before moving primal/dual values) = 8.254744303120898E+11
Dual objective (before moving primal/dual values) = 8.254744303120900E+11
Primal objective (after moving primal/dual values) = 8.254744303120898E+11
Max. rhs perturbation = 2.38419e-06
Max. cost perturbation = 6.82121e-13
Max. primal infeasibility = 6.66827e-07
Max. dual infeasibility = 0
Objective error <= 825478
objective: 8.25474e+11
iterations: 7025832
time: 900.001
deterministic_time: 1307.61

completed solve, status = NOT_SOLVED

1 Answer 1


crossposted from https://groups.google.com/g/or-tools-discuss/c/hBZU_l_BqnI and answered there.

  • $\begingroup$ Thanks, I will try according to your instructions. I didn't know before that this forum is active. $\endgroup$
    – Ying
    Dec 6, 2023 at 13:40
  • $\begingroup$ Exception in thread "main" com.google.ortools.modelbuilder.ModelSolver$ModelSolverException: ModelSolver.getObjectiveValue(): solve() was not called or no solution was found $\endgroup$
    – Ying
    Dec 6, 2023 at 13:49
  • $\begingroup$ of course, a solution was not found. $\endgroup$ Dec 6, 2023 at 13:56
  • $\begingroup$ So in this situation, it is unable to access the solutions data if the status is just DUAL_FEASIBLE? $\endgroup$
    – Ying
    Dec 7, 2023 at 1:52
  • $\begingroup$ I am not the expert at all. But I would expect that a solution needs to be primal feasible. $\endgroup$ Dec 7, 2023 at 3:36

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