1 comment

•  Gurobi Staff

1. I didn't set the limit of the objective function, but the result was Objective range  [1e+00, 1e+00]. I don't understand why this happened. If I want to modify it, how can I modify it?

The coefficient ranges describe the maximum and minimum coefficient in a given object. What is your objective function? You can check which objective function is used by writing your model to an LP file via the gurobi_write() function.

2. The quadratic constraints I set are as follows:

V=sdpvar(11,20,'full');
V_12=sdpvar(11,20,'full');

V22=[12*ones(1,20);V_12];

0<=V,V<=1.1*12
0<=V22,V22<=1.1*1.1*12*12;

V22(i,t)==V(i,t)*V(i,t);

How can I correct the warning in the results?

I assume that the warning you are referring to is the one about possible numerical issues. There are multiple ways to improve numerical behavior of a model. I recommend have a look at our Guidelines for Numerical Issues. However, often as long as your model is solved to optimality and the solution quality is acceptable, there is no need to apply any changes to your model (although it it certainly always strongly recommended).

3. In the last calculation, I got a value of 10 (-6) which is close to 0 but not 0, so I want to make the accuracy of the obtained result larger. If I want to set the accuracy of the result, how should I set it?

You can try decreasing computation tolerances FeasibilityTol, IntFeasTol, and experimenting with the NumericFocus and IntegralityFocus parameters. Note that this might degrade performance.
It is best to manually post-process the solution values. This means that you should check whether the solution values are acceptable or have to be rounded down or up to a certain integer value. Then, you should check whether the polished solution point is still a feasible one. This procedure should definitely be applied to all numerically questionable models.

Best regards,
Jaromił