Originally posted by: Sambuddha

Hi --
I am running a linear program (using CPLEX as the solver); the linear program is coded up in OPL. However, after a run, I would like to
see the values of some of the decision variables, and if the value is sufficiently high, I would like to round it up to 1, and then start another
run. I.e. I would like to set the values of some of the decision variables to 1, and then the next run ought to have these dvars set.

Is there a way to do this in OPL? I am aware that there is such a way in AMPL using the "let" command.

Best,
Sambuddha.
#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi,

you can do that in OPL inside a main block. (flow control)

The keyword is main.

Regards
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: Sambuddha

Hi I do know about the flow control via a main block but I couldn't get any reference for solving my problem, i.e. a version of the "let" command
of AMPL in OPL. Do you know of any reference that I can check? Thanks in advance.
#DecisionOptimization
#OPLusingCPLEXOptimizer

Hi

I will give you a small example

dvar float x in 0..20;
 dvar float y in 0..20;
 
 maximize 2*x+y;
 subject to
 {
   x+y<=20;
 }  
 
 execute
 {
  writeln("x=",x);
  writeln("y=",y);
 }   
 
 main
 {
   thisOplModel.generate();
   cplex.solve();
   thisOplModel.postProcess();
   thisOplModel.x.UB=1;
   thisOplModel.x.LB=1;
   cplex.solve();
   thisOplModel.postProcess();
 }

regards
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: Sambuddha

Hi Alex,

Thanks a lot!

Best,
Sambuddha.
#DecisionOptimization
#OPLusingCPLEXOptimizer