Originally posted by: JDalal

Hi all,

I am facing a strange problem! I am not sure, it may be something trivial that I am missing. Any help is appreciated.

I have a MIP model, where x[i][j] are continuous and y[j] are binary variables. I am solving the model iteratively. In each iteration, I am trying to fix some x[i][j] and some y[j] values, like :

ilo_model.add(x[i][j] == 0.52);
ilo_model.add(y[j] == 1);

this is done within some for loop with i,j index in usual way.

Now, when I am solving the model with above fixed values and using
IloNum x_ij = cplex.getValue(x[i][j]);

I am getting following error :
"ERROR: The referenced IloExtractable has not been extracted by the IloAlgorithm".

I have checked that if I fix some x[i]http://j], the error occurs exactly for that index. I mean if I fix say, x{2[3] = 0.9 then the error comes when I want to use cplex.getValue(x[2][3])! What is the reason??
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Originally posted by: SystemAdmin

This exception usually occurs when the respective variable is not contained in any constraint or the objective of the model. Does variable x[2][3] appear in any constraint that is in the model or in the model's objective? If not, then you need to add it explicitly. Try one of

model.add(x[2][3]);
model.add(x[2][3] >= x[2][3].getLB());

before extracting the model to IloCplex.
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#DecisionOptimization

Originally posted by: JDalal

Yes, the variable is present in several constraints and objective function. I have tried your suggestion too, but still getting same error. Any other possibility?
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#DecisionOptimization

Originally posted by: JDalal

Thanks, it has worked.
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