Isolated a rare bug in intlinprog

The intlinprog function returns that the attached ILP problem (with binary variables only) has no solution. However the attached solution satisfies all constraints. I looked into it extensively to try to be helpful to the Matlab developers and provide a demo script. I am assuming that it has not already been corrected in newer versions of Matlab. Kind regards!

[Tristan S]

If someone verifies this, please let the community know! Thanks!

Step 1) Download the.mat files. Step 2) Load the problem into Matlab, using "load(uigetfile())". Step 3) Type "intlinprog(problem)" to verify that it finds that no integer solution exists. Step 4) Load the solution into memory using "load(uigetfile())". Step 5) Verify that the provided assignment has no unsatisfied constraints:

unsats1=find(problem.Aineq * assignment > problem.bineq);

unsats2=find(problem.Aeq * assignment ~= problem.beq);

unsats3=find(assignment > problem.ub);

unsats4=find(assignment < problem.lb);

unsats5=find(assignment ~= round(assignment));

if isempty([unsats1 ; unsats2; unsats3; unsats4; unsats5]); disp("all are satisfied!"); end

[Tristan S]

A workaroud to avoid this bug in the preprocessor is to use the following, as suggested by https://www.mathworks.com/matlabcentral/answers/278307-no-solution-with-intlinprog#answer_217424 :

problem.options = optimoptions('intlinprog','IntegerPreprocess','none');