Originally posted by: Thomas_321

Hello, 

I do have a problem with my model in Cplex and I really hop you guys can help me with it.

I searched the forum but didn´t find an answer, so I really hope you guys can help me with this.

 

So I simplified my model and this is where I do get the error message: CPLEX (default) cannot extract the expression.

 

I assume it has something to do with the devision but I can´t figure out a way around it.

Model:

//Set

{string} K = ...;

 

//Parameters

float p_l[K] = ...; 
float p_i[K] = ...;

 

// Decision variable

dvar boolean x[K];

 

// Decision expression

dexpr float L = sum (k in K) (p_l[k]*x[k]);
dexpr float I = sum (k in K) (p_i[k]*(1-x[k]));

dexpr float obj = L/(L+I); //CPLEX(default) cannot extract the expression

 

//Target function

minimize obj ;

 

Data:

// Set

K = {K1,K2,K3,K4,K5,K6,K7,K8,K9,K10,K11};

// Parameters
p_l = [257.1, 103.38, 192.26, 190.34, 200.45, 2.50, 36.21, 500.50, 9.03, 2.54, 27.24];
p_i = [173.4, 112.50, 212.00, 137.50, 215.20, 3.00, 32.21, 510.20, 9.55, 4.08, 36.66];

 

 

 

Thank you for your help!!!

 

#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi,

the / turned your model into a non linear one so you should use CPO:

At the top of the model, add

using CP;

and it will work fine

regards

#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: Thomas_321

HI,

 

it worked,

Thanks a lot!

#DecisionOptimization
#OPLusingCPLEXOptimizer