solve function is not working in R2022a Update 5

Hi :)

After updating to R2022a Update 5 version of MATLAB, the "solve" function is not working as it did before.

Diagnozing the problem should start with getting the minimal working example, so I "copy-pasted" the short code from MATLAB Documentation on function "solve" (see below). Unexpectedly, running this code resulted in exactly the same error message, as the one I get while running my own program.

I would appreciate your comments and hints on this case.

Thank you,

Grzegorz

Here is the code "copy-pasted" from MATLAB Documentation:

  x = optimvar('x');
      y = optimvar('y');
      prob = optimproblem;
      prob.Objective = -x - y/3;
      prob.Constraints.cons1 = x + y <= 2;
      prob.Constraints.cons2 = x + y/4 <= 1;
      prob.Constraints.cons3 = x - y <= 2;
      prob.Constraints.cons4 = x/4 + y >= -1;
      prob.Constraints.cons5 = x + y >= 1;
      prob.Constraints.cons6 = -x + y <= 2;
      sol = solve(prob)

Here is the error message:

Solving problem using linprog.

ERROR - (linprog): problem must contain at least "f", "A" and "b".

Error using optim.problemdef.OptimizationProblem/solve

Output argument "x" (and possibly others) not assigned a value in the execution with "linprog" function.

[Bruno Luong]

Work for me

>>         x = optimvar('x');
      y = optimvar('y');
      prob = optimproblem;
      prob.Objective = -x - y/3;
      prob.Constraints.cons1 = x + y <= 2;
      prob.Constraints.cons2 = x + y/4 <= 1;
      prob.Constraints.cons3 = x - y <= 2;
      prob.Constraints.cons4 = x/4 + y >= -1;
      prob.Constraints.cons5 = x + y >= 1;
      prob.Constraints.cons6 = -x + y <= 2;
      sol = solve(prob)

Solving problem using linprog.

Optimal solution found.


sol = 

  struct with fields:

    x: 0.6667
    y: 1.3333

>> ver
-----------------------------------------------------------------------------------------------------
MATLAB Version: 9.12.0.2039608 (R2022a) Update 5

[Grzegorz Dzierzanowski]

Thank you, Bruno.

My guess is that the third-party software, which I am using with MATLAB, overloads the original solve command.

Anyway, thanks for your comment.

Best,

Grzegorz

[SamVector]

Hello? Has the problem been solved?

[Matt J]

@SamVector Yes, the problem has been solved.

[SamVector]

Excuse me, but I faced the same problem lately, and I want to know how exactly did you do to solve the problem? Which third party software is likely to cause the trouble? Thanks in advance🙏

[Walter Roberson]

which -all solve

[SamVector]

Thanks. Although I have no idea how the problem has been solved, The problem vanished after I reinstall the Optimization toolbox. I think it may be conflit with the matpower toolbox I installed.