Originally posted by: FANS_Nader_Al_Theeb

Hello

I have an unrestricted variables with bounds (-400,400) defined as following

IloNumVarArray3 dev_aot(env,nbComm);   

for( a = 0; a < nbComm; a++) 
{ dev_aot[a] = IloNumVarArray2 (env, nbDNodes); 

for( o=0; o<nbDNodes; o++) 
{ dev_aot[a][o] = IloNumVarArray (env, nbTimes,  -400, 400);    
}    
}

And I have constraint as in the following

model.add(dev_aot[a][o][t] == daot[a][o][t] - ZD - dev_aot[a][o][t-1]);

but I need to use the

dev_aot[a][o][t-1]

only if it is negative

In CPLEX, we can't use if statement with variable conditions like the following

if (dev_aot[a][o][t-1] <=0 ) 
{model.add(dev_aot[a][o][t] == daot[a][o][t] - ZD - dev_aot[a][o][t-1]);
}   

if (dev_aot[a][o][t-1] >=0 ) 
{model.add(dev_aot[a][o][t] == daot[a][o][t] - ZD );
}

So, is there any other method to use the variable only when its value is negative

Thanks
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

Did you try the IloCplex::ifThen() method?
That should allow you to implement the two 'if' conditions you listed.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: FANS_Nader_Al_Theeb

Thank you Daniel

Can you show me a simple example, because I received an error

‘ifThen’ is not a member of ‘IloCplex’

May be I write the command incorrectly

Thanks a lot
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

Sorry, ifThen() is for Java Concert. In C++ Concert use class IloIfThen.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: FANS_Nader_Al_Theeb

I forget to mention that I'm using CPLEX - concert technology

Thanks
#CPLEXOptimizers
#DecisionOptimization