static void SolveDual3(GRBEnv env, HashSet <string> nodes_set, List <Arc> arcs)
{
GRBModel dual = new GRBModel(env);
Dictionary <string, GRBConstr> flow_balance = new Dictionary <string, GRBConstr>();
Dictionary <Arc, GRBVar> arc_traversed = new Dictionary <Arc, GRBVar>();
GRBConstr[] constrs = dual.AddConstrs(nodes_set.Count);
dual.Update();
int i = 0;
foreach (string s in nodes_set)
{
GRBConstr con = constrs[i];
con.Set(GRB.StringAttr.ConstrName, "flow_balance." + s);
con.Set(GRB.CharAttr.Sense, GRB.EQUAL);
flow_balance[s] = con;
++i;
}
flow_balance[ORIGIN].Set(GRB.DoubleAttr.RHS, -1);
flow_balance[DESTINATION].Set(GRB.DoubleAttr.RHS, 1);
foreach (Arc a in arcs)
{
GRBColumn col = new GRBColumn();
col.AddTerm(1, flow_balance[a.dest]);
col.AddTerm(-1, flow_balance[a.source]);
arc_traversed[a] = dual.AddVar(0, 1, a.length, GRB.CONTINUOUS, col, "arc_traversed." + a.source + "." + a.dest);
}
dual.Optimize();
dual.Write("dual3.lp");
dual.Write("dual3.sol");
dual.Dispose();
}
private void btnUpdate_3_Click(object sender, EventArgs e)
{
string sense = this.cmbSense.GetItemText(this.cmbSense.SelectedItem);
switch (sense)
{
case "EQUAL":
constraint.Set(GRB.CharAttr.Sense, '=');
break;
case "LESS EQUAL":
constraint.Set(GRB.CharAttr.Sense, '<');
break;
case "GREATER EQUAL":
constraint.Set(GRB.CharAttr.Sense, '>');
break;
}
//display constraint
MyGlobals.model.Update();
populate_cmbConstraint();
BtnOK.Enabled = true;
BtnCancel.Enabled = false;
lblUpdate3.Text = "";
lblUpdate3.Text = constraint.Get(GRB.StringAttr.ConstrName) + ": ";
GRBLinExpr con_info = (GRBLinExpr)MyGlobals.model.GetRow(constraint);
for (int n = 0; n < con_info.Size; n++)
{
lblUpdate3.Text += " " + con_info.GetCoeff(n) + con_info.GetVar(n).Get(GRB.StringAttr.VarName) + " +";
}
lblUpdate3.Text += " " + constraint.Get(GRB.CharAttr.Sense) + " " + constraint.Get(GRB.DoubleAttr.RHS) + "\n";
}
