Decision Optimization

Originally posted by: Ahlem

Is it possible to fill an array of  IloNumVar with integer values using cplex in java ?

Because, I have a variable declared with this way: IloNumVar[][][] c = new IloNumVar[job][][]; 

and I want to fill it with integer values. 

How can i do this ?

You cannot. An IloNumVar is an object. What is the semantics of assigning a number to such an object? Why not declare the array to be an array of ints if you want to assign integers?

Originally posted by: Ahlem

Because I can not use it (the array of ints) after in my constraints. The program does not accept. 

Is there another method I can use? (To more explain I have attached my constraint )

//My ilonumvar is c[i][j][k]
IloNumVar[][][] c = new IloNumVar[job][][];
int [][][] p= new int[job][][];
IloNumVar[][][][][] y = new IloNumVar[job][][][][];
int L =10000;

cplex.addGe(c[i1][j1][k],
                         cplex.sum(c[i2][j2][k], cplex.prod(y[i1][j1][i2][j2][k], p[i1][j1][k]),
                                                                                        cplex.sum(-L, cplex.prod(L, y[i2][j2][i1][j1][k]))));

You should

• Take a look at the various examples shipped with CPLEX,
• Take a look at the reference documentation
• Try to better understand the error messages your compiler gives you

Either 'c' is a variable subject to optimization or it is a constant. Apparently, in your case it is a variable. That is a property that cannot change. If you try to feed 'c' to a function and then get an error then the fix is not to change the type of 'c' from variable to constant! Instead you should check whether there is another function you can use or whether you have to do things in a different way.

In your code I don't see a problem with the way you use 'c'. But I see a problem with how you use 'L': This is an integer constant and cannot be mixed with objects that represent linear expressions in all cases. You may want to use something like cplex.linearNumExpr(L) and cplex.linearNumExpr(-L) to create expression objects that represents these constants.

Originally posted by: Ahlem

Thanx you 

You know how can i convert an OPL coded model to Java? 

I have a code in cplex but I want to convert it automatically just to test it with java. is there a quick solution or should I rewrite it?

There is no automatic tool for that, so you have to do it by hand.

But note that you can solve OPL models also from Java, see opl/examples/opl_interfaces/java/oplrunsample.

Originally posted by: Ahlem

Hi, 

But, eclipse shows me this error 

I think because this two error in cplex : i have two errors : 

The first : OPL runtime not available, please check your PATH

The second : 

Please help me how can i resolve them ? 

Regards.

Can you please show the full command line with which you invoke the JVM? In particular, the setting of java.library.path? What operating system are you running on? Windows, Linux, ...?

Originally posted by: Ahlem

The problem of the error in eclipse is solved. Thanx you 

Sorry, but I have one more question. Can i help me please in this problem : https://www.ibm.com/developerworks/community/forums/html/topic?id=dbbb788c-f978-499a-9d09-5d63fabd2206