Originally posted by: SystemAdmin

[g.vandenmoort said:]

I am having issued retrieving the dual value for my constraints.  It should be straightforward but I have no clue what I'm doing wrong.  Here is my script



//int numEdges = 4;
int maxNode = 4;
//range EDGES = 1..numEdges;
range Node = 1..maxNode;
tuple Edge {
    int head;
    int tail;
    float capacity;
    float index;
    };
{Edge} edges = {<1,2,1.3,1>,<2,3,2.3,2>,<3,4,1.4,3>,<1,4,10.7,4>};
float cost[edges] = [ 1, 2, 3, 7];

dvar float+ p[edges];

minimize sum(x in edges) cost[x]*p[x];
subject to {
    balance:forall(y in Node: y != 1 && y != maxNode) {
        sum(x in edges:x.head==y) p[x]- sum(z in edges:z.tail==y) p[z] == 0;
    }
    toSink:sum(x in edges:x.tail==maxNode) p[x] == 0.5;
    capacity:forall(x in edges) p[x]<=x.capacity;    <br />}
execute{
    for(var x in edges) {
        writeln(capacity[x].dual);
    }



Thanks in advance.
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[alain.chabrier said:]

Hi,

just change the definition of capacity to :

    forall(x in edges)
    capacity:p[x]<=x.capacity;  <br />
Alain
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[g.vandenmoort said:]

Alain, I think the most important part of your post is missing.  Can you repost it using the "post as code" tag?  Thanks.

#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[rocarvaj said:]

[quote author=alain.chabrier link=topic=351.msg990#msg990 date=1213949248]
Hi,

just change the definition of capacity to :

    forall(x in edges)
    capacity:p[x]<=x.capacity;   <br />
Alain


What Alain was trying to say is that you have to label constrains inside forall loops.

I hope the quote looks right...
#DecisionOptimization
#OPLusingCPLEXOptimizer

Originally posted by: SystemAdmin

[alain.chabrier said:]

Yes, sorry, the HTML scrambled my answer.

Alain


#DecisionOptimization
#OPLusingCPLEXOptimizer