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 aGRBQConstr
constructor.- 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");
' Create variables Dim x As GRBVar = model.AddVar(-2.0, 2.0, 0.0, GRB.CONTINUOUS, "x") Dim y As GRBVar = model.AddVar(0.0, 3.0, 0.0, GRB.CONTINUOUS, "y") ' Add quadratic constraint x^2 + x*y + y = 0 with name c1 Dim constr As GRBQConstr = model.AddQConstr(x*x + x*y + y == 0, "c1")
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 theGRBModel
object (GRBModel.Get
).The full list of attributes can be found in the Attributes section of this document. Examples of how to query and set attributes can also be found in this section.
- 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);
' Get constraint sense Dim sense As Char = 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);
' Get RHS Dim rhs As Double = 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);
' Get information whether constraint participates in a ' previously computed IIS Dim iisqconstr As Integer = 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);
' Get constraint name Dim name As String = 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, '>');
' 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);
' 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);
' 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");
' Set constraint name constr.Set(GRB.StringAttr.QCName, "newName")