Solved in 0 iterations and 0.02 seconds Infeasible or unbounded model
AnsweredWhen I use Gurobi on matlab to solve a LP, I receive the following in the command window, and I want to know whether this is an issue or not? In other words, is the solution I got at the end is correct?
>> Running_Codes_2_VCG
Academic license  for noncommercial use only
Optimize a model with 77 rows, 73 columns and 149 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 1 rows and 1 columns
Presolve time: 0.00s
Solved in 0 iterations and 0.00 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 153 rows, 73 columns and 225 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 1 rows and 1 columns
Presolve time: 0.02s
Solved in 0 iterations and 0.03 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 231 rows, 73 columns and 303 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 1 rows and 1 columns
Presolve time: 0.02s
Solved in 0 iterations and 0.02 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 309 rows, 73 columns and 381 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 1 rows and 1 columns
Presolve time: 0.02s
Solved in 0 iterations and 0.02 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 387 rows, 73 columns and 459 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 14 rows and 207 columns
Presolve time: 0.02s
Solved in 0 iterations and 0.02 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 469 rows, 73 columns and 541 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 19 rows and 253 columns
Presolve time: 0.02s
Solved in 0 iterations and 0.02 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 549 rows, 73 columns and 621 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 23 rows and 297 columns
Presolve time: 0.02s
Solved in 0 iterations and 0.02 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 631 rows, 73 columns and 703 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 28 rows and 343 columns
Presolve time: 0.00s
Solved in 0 iterations and 0.02 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 713 rows, 73 columns and 785 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 33 rows and 389 columns
Presolve time: 0.02s
Solved in 0 iterations and 0.02 seconds
Infeasible or unbounded model
Academic license  for noncommercial use only
Optimize a model with 795 rows, 73 columns and 867 nonzeros
Coefficient statistics:
Matrix range [1e+00, 1e+00]
Objective range [1e01, 1e+01]
Bounds range [0e+00, 0e+00]
RHS range [2e+00, 5e+01]
Presolve removed 0 rows and 721 columns
Presolve time: 0.02s
Presolved: 73 rows, 74 columns, 146 nonzeros
Iteration Objective Primal Inf. Dual Inf. Time
0 5.1220444e+03 0.000000e+00 5.968396e+01 0s
37 2.1111904e+03 0.000000e+00 0.000000e+00 0s
Solved in 37 iterations and 0.03 seconds
Optimal objective 2.111190358e+03

Hi Mohamed,
The first nine models you solve are either infeasible or unbounded. The last model you solve is feasible with an optimal objective value of 2111.190358. Is this different from what you expected?
Thanks!
Eli
0 
Thanks for your comment!
They are for the same model. When I run the model, it executes multiple iterations, with each iteration saying "Infeasible or unbounded model", except the last one when it reaches a feasible solution. I hope it is clearer now.
0 
Hi Mohamed,
Based on the log files, it looks like the MATLAB code you're running iteratively adds constraints to the model and resolves it until the model has a finite solution. This looks normal to me. However, I can't say anything about the correctness of the MATLAB code, as this depends on the theory behind the algorithm and the correctness of the implementation.
Thanks!
Eli
0 
Hi Eli,
Thank you so much for your feedback.
Mohamed
0
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