coin-or
Nonzero optimal objective value has been found, but the solution file reports objective zero
hi, I am solving an integer programming problem with CBC in python. I solve the model with parameters mod.solve(pulp.solvers.PULP_CBC_CMD(msg=1,fracGap=0.01, threads=4)). From the log output by cbc, it shows that the optimal solution has been found with nonzero objective value. But the solution file reports zero objective value.
the log:
Continuous objective value is -2.81426e+06 - 0.50 seconds
Cgl0003I 0 fixed, 667 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 53 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 32 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 28 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 24 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 20 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 16 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 12 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 8 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0004I processed model has 889 rows, 5065 columns (4985 integer (824 of which binary)) and 11691 elements
Cbc0012I Integer solution of -2814259.3 found by DiveCoefficient after 0 iterations and 0 nodes (1.85 seconds)
Cbc0030I Thread 0 used 0 times, waiting to start 0.077954054, 0 cpu time, 0 locks, 0 locked, 0 waiting for locks
Cbc0030I Thread 1 used 0 times, waiting to start 0.05874896, 0 cpu time, 0 locks, 0 locked, 0 waiting for locks
Cbc0030I Thread 2 used 0 times, waiting to start 0.031897783, 0 cpu time, 0 locks, 0 locked, 0 waiting for locks
Cbc0030I Thread 3 used 0 times, waiting to start 0.0037698746, 0 cpu time, 0 locks, 0 locked, 0 waiting for locks
Cbc0030I Main thread 0 waiting for threads, 1 locks, 3.0994415e-05 locked, 0 waiting for locks
Cbc0011I Exiting as integer gap of 0.00039978093 less than 1e-10 or 1%
Cbc0001I Search completed - best objective -2814259.285720068, took 0 iterations and 0 nodes (1.99 seconds)
Cbc0035I Maximum depth 0, 0 variables fixed on reduced cost
0 Obj -2814259.3 Primal inf 1.976664e-07 (4) Dual inf 8.28333e+10 (18)
Perturbing problem by 0.001 % of 305.016 - largest nonzero change 0.0011799954 (% 0.0010025205) - largest zero change 1.9732058e-05
4 Obj -2814259.3 Primal inf 1.9499971e-07 (3)
4 Obj -2814259.3 Primal inf 1.9499971e-07 (3)
4 Obj -2814259.3 Primal inf 1.9499971e-07 (3)
4 Obj -2814259.3 Primal inf 1.9499971e-07 (3)
4 Obj -2814259.3 Primal inf 1.9499971e-07 (3)
4 Obj -2814259.3 Primal inf 1.9499971e-07 (3)
4 Obj -2814259.3 Primal inf 1.9499971e-07 (3)
Primal infeasible - objective value -2814259.3
Cuts at root node changed objective from -2.81426e+06 to -2.81426e+06
Probing was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Gomory was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Knapsack was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Clique was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
MixedIntegerRounding2 was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
FlowCover was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
TwoMirCuts was tried 0 times and created 0 cuts of which 0 were active after adding rounds of cuts (0.000 seconds)
Cgl0013I Postprocessed model is infeasible - possible tolerance issue - try without preprocessing
395 relaxed row infeasibilities - summing to 123122
395 relaxed row infeasibilities - summing to 123122
395 relaxed row infeasibilities - summing to 123122
Result - Optimal solution found (within gap tolerance)
Objective value: -2814259.28571564 Lower bound: -2814259.286 Gap: 0.00 Enumerated nodes: 0 Total iterations: 0 Time (CPU seconds): 5.09 Time (Wallclock seconds): 6.16
Option for printingOptions changed from normal to all Total time (CPU seconds): 5.86 (Wallclock seconds): 7.00
-0.0 Optimal
I can't figure out why the objective value has been changed to zero and the solution file reports zero objective value.
CBC does not reports zero as objective function in your screenshot. Seems like a pulp issue.
Em sex, 9 de ago de 2019 05:25, rantaoran [email protected] escreveu:
hi, I am solving an integer programming problem with CBC in python. I solve the model with parameters mod.solve(pulp.solvers.PULP_CBC_CMD(msg=1,fracGap=0.01, threads=4)). From the log output by cbc, it shows that the optimal solution has been found with nonzero objective value. But the solution file reports zero objective value.
[image: image] https://user-images.githubusercontent.com/34907246/62751349-f5e79880-ba95-11e9-82e3-da274df1d1c1.png
I can't figure out why the objective value has been changed to zero and the solution file reports zero objective value.
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Hi @h-g-s , I've checked the solution file CBC generated and the solution file reports zero as objective value, so is mod.objective.value(). I can't figure out why the solution file reports zero objective value.
the following is part of the solution file:
CBC does not reports zero as objective function in your screenshot. Seems like a pulp issue. Em sex, 9 de ago de 2019 05:25, rantaoran [email protected] escreveu: … hi, I am solving an integer programming problem with CBC in python. I solve the model with parameters mod.solve(pulp.solvers.PULP_CBC_CMD(msg=1,fracGap=0.01, threads=4)). From the log output by cbc, it shows that the optimal solution has been found with nonzero objective value. But the solution file reports zero objective value. [image: image] https://user-images.githubusercontent.com/34907246/62751349-f5e79880-ba95-11e9-82e3-da274df1d1c1.png I can't figure out why the objective value has been changed to zero and the solution file reports zero objective value. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#246?email_source=notifications&email_token=AB4VZOTOIXGCZBFMYO3GYJLQDTPRJA5CNFSM4IKQE6H2YY3PNVWWK3TUL52HS4DFUVEXG43VMWVGG33NNVSW45C7NFSM4HEJSBOQ>, or mute the thread https://github.com/notifications/unsubscribe-auth/AB4VZOS3YHRGZQKHQ4T7YXDQDTPRJANCNFSM4IKQE6HQ .
Hi, I have the same issue here. I get a nonzero objective value (with msg=1 log), but pulp.value(model.objective)) return zero.
