static void Main(string[] args)
{
if (args.Length < 1)
{
Console.Out.WriteLine("Usage: mip2_cs filename");
return;
}
try {
GRBEnv env = new GRBEnv();
GRBModel model = new GRBModel(env, args[0]);
if (model.IsMIP == 0)
{
Console.WriteLine("Model is not a MIP");
return;
}
model.Optimize();
int optimstatus = model.Status;
double objval = 0;
if (optimstatus == GRB.Status.OPTIMAL)
{
objval = model.ObjVal;
Console.WriteLine("Optimal objective: " + objval);
}
else if (optimstatus == GRB.Status.INF_OR_UNBD)
{
Console.WriteLine("Model is infeasible or unbounded");
return;
}
else if (optimstatus == GRB.Status.INFEASIBLE)
{
Console.WriteLine("Model is infeasible");
return;
}
else if (optimstatus == GRB.Status.UNBOUNDED)
{
Console.WriteLine("Model is unbounded");
return;
}
else
{
Console.WriteLine("Optimization was stopped with status = "
+ optimstatus);
return;
}
/* Iterate over the solutions and compute the objectives */
GRBVar[] vars = model.GetVars();
model.Parameters.OutputFlag = 0;
Console.WriteLine();
for (int k = 0; k < model.SolCount; ++k)
{
model.Parameters.SolutionNumber = k;
double objn = 0.0;
for (int j = 0; j < vars.Length; j++)
{
objn += vars[j].Obj * vars[j].Xn;
}
Console.WriteLine("Solution " + k + " has objective: " + objn);
}
Console.WriteLine();
model.Parameters.OutputFlag = 1;
/* Create a fixed model, turn off presolve and solve */
GRBModel fixedmodel = model.FixedModel();
fixedmodel.Parameters.Presolve = 0;
fixedmodel.Optimize();
int foptimstatus = fixedmodel.Status;
if (foptimstatus != GRB.Status.OPTIMAL)
{
Console.WriteLine("Error: fixed model isn't optimal");
return;
}
double fobjval = fixedmodel.ObjVal;
if (Math.Abs(fobjval - objval) > 1.0e-6 * (1.0 + Math.Abs(objval)))
{
Console.WriteLine("Error: objective values are different");
return;
}
GRBVar[] fvars = fixedmodel.GetVars();
double[] x = fixedmodel.Get(GRB.DoubleAttr.X, fvars);
string[] vnames = fixedmodel.Get(GRB.StringAttr.VarName, fvars);
for (int j = 0; j < fvars.Length; j++)
{
if (x[j] != 0.0)
{
Console.WriteLine(vnames[j] + " " + x[j]);
}
}
// Dispose of models and env
fixedmodel.Dispose();
model.Dispose();
env.Dispose();
} catch (GRBException e) {
Console.WriteLine("Error code: " + e.ErrorCode + ". " + e.Message);
}
}
static void Main(string[] args)
{
if (args.Length < 1) {
Console.Out.WriteLine("Usage: mip2_cs filename");
return;
}
try {
GRBEnv env = new GRBEnv();
GRBModel model = new GRBModel(env, args[0]);
if (model.Get(GRB.IntAttr.IsMIP) == 0) {
Console.WriteLine("Model is not a MIP");
return;
}
model.Optimize();
int optimstatus = model.Get(GRB.IntAttr.Status);
double objval = 0;
if (optimstatus == GRB.Status.OPTIMAL) {
objval = model.Get(GRB.DoubleAttr.ObjVal);
Console.WriteLine("Optimal objective: " + objval);
} else if (optimstatus == GRB.Status.INF_OR_UNBD) {
Console.WriteLine("Model is infeasible or unbounded");
return;
} else if (optimstatus == GRB.Status.INFEASIBLE) {
Console.WriteLine("Model is infeasible");
return;
} else if (optimstatus == GRB.Status.UNBOUNDED) {
Console.WriteLine("Model is unbounded");
return;
} else {
Console.WriteLine("Optimization was stopped with status = "
+ optimstatus);
return;
}
/* Iterate over the solutions and compute the objectives */
GRBVar[] vars = model.GetVars();
model.GetEnv().Set(GRB.IntParam.OutputFlag, 0);
Console.WriteLine();
for (int k = 0; k < model.Get(GRB.IntAttr.SolCount); ++k) {
model.GetEnv().Set(GRB.IntParam.SolutionNumber, k);
double objn = 0.0;
for (int j = 0; j < vars.Length; j++) {
objn += vars[j].Get(GRB.DoubleAttr.Obj)
* vars[j].Get(GRB.DoubleAttr.Xn);
}
Console.WriteLine("Solution " + k + " has objective: " + objn);
}
Console.WriteLine();
model.GetEnv().Set(GRB.IntParam.OutputFlag, 1);
/* Create a fixed model, turn off presolve and solve */
GRBModel fixedmodel = model.FixedModel();
fixedmodel.GetEnv().Set(GRB.IntParam.Presolve, 0);
fixedmodel.Optimize();
int foptimstatus = fixedmodel.Get(GRB.IntAttr.Status);
if (foptimstatus != GRB.Status.OPTIMAL) {
Console.WriteLine("Error: fixed model isn't optimal");
return;
}
double fobjval = fixedmodel.Get(GRB.DoubleAttr.ObjVal);
if (Math.Abs(fobjval - objval) > 1.0e-6 * (1.0 + Math.Abs(objval))) {
Console.WriteLine("Error: objective values are different");
return;
}
GRBVar[] fvars = fixedmodel.GetVars();
double[] x = fixedmodel.Get(GRB.DoubleAttr.X, fvars);
string[] vnames = fixedmodel.Get(GRB.StringAttr.VarName, fvars);
for (int j = 0; j < fvars.Length; j++) {
if (x[j] != 0.0) Console.WriteLine(vnames[j] + " " + x[j]);
}
// Dispose of models and env
fixedmodel.Dispose();
model.Dispose();
env.Dispose();
} catch (GRBException e) {
Console.WriteLine("Error code: " + e.ErrorCode + ". " + e.Message);
}
}