GRBQConstr#

GRBQConstr#

Gurobi quadratic constraint object. Quadratic constraints are always associated with a particular model. You create a quadratic constraint object by adding a quadratic constraint to a model (using GRBModel.AddQConstr), rather than by using a GRBQConstr constructor.

The methods on quadratic constraint objects are used to get and set quadratic constraint attributes. For example, quadratic constraint right-hand sides can be queried by calling Get (GRB.DoubleAttr.QCRHS). Note, however, that it is generally more efficient to query attributes for a set of constraints at once. This is done using the attribute query method on the GRBModel object (GRBModel.Get).

Example:
// Create variables
GRBVar x = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x");
GRBVar y = model.AddVar(0.0, 3.0, 0.0, GRB.CONTINUOUS, "y");
// Add quadratic constraint x^2 + x*y + y = 0 with name c1
GRBQConstr constr = model.AddQConstr(x*x + x*y + y == 0, "c1");
char Get(GRB.CharAttr attr)#

Query the value of a char-valued quadratic constraint attribute.

Parameters:

attr – The attribute being queried.

Returns:

The current value of the requested attribute.

Example:
// Get constraint sense
char sense = constr.Get(GRB.CharAttr.QCSense);
double Get(GRB.DoubleAttr attr)#

Query the value of a double-valued quadratic constraint attribute.

Parameters:

attr – The attribute being queried.

Returns:

The current value of the requested attribute.

Example:
// Get RHS
double rhs = constr.Get(GRB.DoubleAttr.QCRHS);
int Get(GRB.IntAttr attr)#

Query the value of an int-valued quadratic constraint attribute.

Parameters:

attr – The attribute being queried.

Returns:

The current value of the requested attribute.

Example:
// Get information whether constraint participates in a
// previously computed IIS
int iisqconstr = constr.Get(GRB.IntAttr.IISQConstr);
string Get(GRB.StringAttr attr)#

Query the value of a string-valued quadratic constraint attribute.

Parameters:

attr – The attribute being queried.

Returns:

The current value of the requested attribute.

Example:
// Get constraint name
string name = constr.Get(GRB.StringAttr.QCName);
void Set(GRB.CharAttr attr, char newvalue)#

Set the value of a char-valued quadratic constraint attribute.

Parameters:

  • attr – The attribute being modified.

  • newvalue – The desired new value of the attribute.

Example:
// Set constraint sense
constr.Set(GRB.CharAttr.QCSense, '>');
void Set(GRB.DoubleAttr attr, double newvalue)#

Set the value of a double-valued quadratic constraint attribute.

Parameters:

  • attr – The attribute being modified.

  • newvalue – The desired new value of the attribute.

Example:
// Set RHS
constr.Set(GRB.DoubleAttr.QCRHS, 2.0);
void Set(GRB.IntAttr attr, int newvalue)#

Set the value of an int-valued quadratic constraint attribute.

Parameters:

  • attr – The attribute being modified.

  • newvalue – The desired new value of the attribute.

Example:
// Force constraint into IIS
constr.Set(GRB.IntAttr.IISQConstrForce, 1);
void Set(GRB.StringAttr attr, string newvalue)#

Set the value of a string-valued quadratic constraint attribute.

Parameters:

  • attr – The attribute being modified.

  • newvalue – The desired new value of the attribute.

Example:
// Set constraint name
constr.Set(GRB.StringAttr.QCName, "newName");