bool SolveMaster()
{
_grbModel.Optimize();
int status = _grbModel.Get(GRB.IntAttr.Status);
int solution = _grbModel.Get(GRB.IntAttr.SolCount);
if (status == GRB.Status.OPTIMAL || (status == GRB.Status.TIME_LIMIT && solution > 0))
{
foreach (Node n in Data.NodeSet)
{
GRBConstr constr = _grbModel.GetConstrByName("ct1_" + n.ID);
Dual[n] = constr.Get(GRB.DoubleAttr.Pi);
n.ParseSolution(2);
n.ParseSolution(1);
}
foreach (Arc a in Data.ArcSet)
{
a.ParseSolution();
}
double k0 = _grbModel.GetVarByName("k_0").Get(GRB.DoubleAttr.X);
double k1 = _grbModel.GetVarByName("k_1").Get(GRB.DoubleAttr.X);
return(true);
}
else
{
return(false);
}
}
static void SolvePrimal(GRBEnv env, HashSet <string> nodes_set, List <Arc> arcs)
{
GRBModel m = new GRBModel(env);
Dictionary <string, GRBVar> distances = new Dictionary <string, GRBVar>(); // pi
foreach (string node in nodes_set)
{
distances[node] = m.AddVar(0, GRB.INFINITY, 0, GRB.CONTINUOUS, "distance." + node);
}
m.Update();
distances[ORIGIN].Set(GRB.DoubleAttr.Obj, -1);
distances[DESTINATION].Set(GRB.DoubleAttr.Obj, 1);
m.Set(GRB.IntAttr.ModelSense, -1);
Dictionary <Arc, GRBConstr> constrs = new Dictionary <Arc, GRBConstr>();
foreach (Arc a in arcs)
{
constrs[a] = m.AddConstr(distances[a.dest] <= distances[a.source] + a.length, "distance_con." + a.source + "." + a.dest);
}
m.Update();
m.Write("shortest_path.lp");
m.Optimize();
foreach (var pair in distances)
{
Console.WriteLine("distance to {0} is {1}", pair.Key, pair.Value.Get(GRB.DoubleAttr.X));
}
foreach (var pair in constrs)
{
GRBConstr con = pair.Value;
if (con.Get(GRB.DoubleAttr.Pi) > 0.5)
{
Console.WriteLine("Arc {0}, {1} is in shortest path", pair.Key.source, pair.Key.dest);
}
}
Console.WriteLine("Length of shortest path is {0}", m.Get(GRB.DoubleAttr.ObjVal));
m.Dispose();
}
//Add variable
private void btnUpdate_Click(object sender, EventArgs e)
{
{
try
{
//change GRBConst into GRBConst[]
GRBConstr[] CON = new GRBConstr[1];
CON[0] = constraint;
double var_coco;
double.TryParse(txtAddCon.Text, out var_coco);
//change double into double[]
Double[] COEFF = new Double[1];
COEFF[0] = var_coco;
//add variable to constraint
MyGlobals.model.ChgCoeff(constraint, variable, var_coco);
MyGlobals.model.Update();
populate_cmbConstraint();
BtnOK.Enabled = true;
BtnCancel.Enabled = false;
lblUpdate.Text = "";
lblUpdate.Text = constraint.Get(GRB.StringAttr.ConstrName) + ": ";
GRBLinExpr con_info = (GRBLinExpr)MyGlobals.model.GetRow(constraint);
for (int n = 0; n < con_info.Size; n++)
{
lblUpdate.Text += " " + con_info.GetCoeff(n) + con_info.GetVar(n).Get(GRB.StringAttr.VarName) + " +";
}
lblUpdate.Text += " " + constraint.Get(GRB.CharAttr.Sense) + " " + constraint.Get(GRB.DoubleAttr.RHS) + "\n";
}
catch (GRBException exc)
{
MessageBox.Show("Error code: " + exc.ErrorCode + ". " + exc.Message, "Error occured", MessageBoxButtons.OK);
}
}
}
