intlinprog returns non-optimal solution. Can you help me finding the problem?

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I have large constraint Matrix A,b, Aeq, beq. I select an easy case where I know the solution for x (and negative cost) and I can prove true:
logical(A*x_example <= b)
logical(Aeq*x_example == beq)
logical(x_example >= lb )
logical(x_example <= ub)
But intlinprog returns a result with zero cost.
options = optimoptions('intlinprog','Display','final');
[x_sol,fval,eflag,output] = intlinprog(-f,1:length(f),A,b,Aeq,beq,lb,ub,options);
This is a my cost (positiv real) function f =
(1,1) 0.2300
(3,1) 0.1069
(4,1) 0.2700
(5,1) 0.0400
(6,1) 0.1100
(8,1) 4.0000
(15,1) 0.2300
(19,1) 4.0000
%...
(106,1) 0.2300
(108,1) 0.1069
(109,1) 0.2700
(110,1) 0.0400
(111,1) 0.1100
(113,1) 4.0000
(120,1) 0.2300
(124,1) 4.0000

Respuestas (1)

Frederik Hesselmann
Frederik Hesselmann el 21 de Feb. de 2018
Editada: Frederik Hesselmann el 21 de Feb. de 2018
I found two Problems.
the function 'logical()' doesnt care about whether x is integer or not. The solution I have suggested is not integer. This is the reason why my test using 'logical()' wasnt correct. Checking 'isinteger(x)' is also necessary.
Though this doesnt explain why my result is wrong using 'intlinprog' but I know now that I have to look in the constraints. I found indeed that due to cutting of digits some equalities are violated. Using boundary solves the problem.
  1 comentario
Nicola Blasuttigh
Nicola Blasuttigh el 1 de Dic. de 2021
Hi man, sorry but probably I have the same problem about cutting digits. How do you solve it? What do you mean with boundary?
Thanks

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