problem based approach- script running but does not gives a solution

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hello everyone i am working on a problem where i choosed problem based approach to solve it. I am very new to MATLAB so i do not know what i am doing wrong but here is my question:
the script is running but it does not gives me any solution it just says 'Solving problem using ga' (i want to solve with ga). I dont think it iterates. I have set stopping criterias that is not the problem. I have been looking to find answers to my problem but could not find any. Anyhow, if you have any ideas why i am facing this situation and suggestions to solve it i would be appreaciated.
Thank you in advance!
  10 Comments
Matt J
Matt J on 10 Apr 2022
Be mindfull of the (-1) in your function,
z= (-1)*sum(x.*rij.*ai,'all');
Because you have set ObjectiveSense="maximize", the (-1) makes it so that you are effectively minimizing z= sum(x.*rij.*ai,'all').

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Answers (1)

Matt J
Matt J on 10 Apr 2022
There is only one objective, and two constraints so far and they all are linear. When i write my objective function it forces me to use ga. Did not understand why.
It forces you to use ga() because you have specified your objective function using fcn2optimexpr(). When you specify it as below, the solver can tell right away that it is an integer linear program, and solves it very quickly with initlinprog,
load Problem
x=problem.Variables.x;
y=problem.Variables.y;
problem.Objective=sum((x.*rij)*ai);
sol=solve(problem);
Solving problem using intlinprog. LP: Optimal objective value is -1402.268722. Cut Generation: Applied 1 implication cut, and 1 strong CG cut. Lower bound is -1402.000000. Heuristics: Found 1 solution using total rounding, and 1 solution using ZI round. Upper bound is -1089.000000. Relative gap is 28.72%. Heuristics: Found 1 solution using ZI round. Upper bound is -1304.000000. Relative gap is 7.51%. Heuristics: Found 1 solution using 2-opt. Upper bound is -1315.000000. Relative gap is 6.61%. Cut Generation: Applied 11 Gomory cuts, 18 implication cuts, and 3 strong CG cuts. Lower bound is -1383.000000. Relative gap is 5.17%. Branch and Bound: nodes total num int integer relative explored time (s) solution fval gap (%) 10000 1.87 4 -1.315000e+03 1.595745e+00 17766 3.11 4 -1.315000e+03 0.000000e+00 Optimal solution found. Intlinprog stopped because the objective value is within a gap tolerance of the optimal value, options.AbsoluteGapTolerance = 0 (the default value). The intcon variables are integer within tolerance, options.IntegerTolerance = 1e-05 (the default value).
sol.x=round(sol.x);
sol.y=round(sol.y);

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