ilog.concert
Class IloColumn

java.lang.Object
  ilog.concert.IloColumn

public abstract class IloColumn

extends java.lang.Object

Objects of class IloColumn are used to create a variable using column-wise modeling.

In column-wise modeling, newly constructed variables are inserted into existing modeling objects. The term column-wise comes from linear programming, where the constraints are typically represented as a matrix. Adding new variables to the optimization problem corresponds to adding columns to the constraint matrix.

The procedure for column-wise modeling is as follows. Start from an existing set of modeling objects of these classes:

• IloObjective,
• IloRange, and
• IloLPMatrix

For each modeling object affected by the addition of the new variable, call the method IloMPModeler.column with the object as an argument, along with the other arguments needed to install a new variable in the existing modeling objects. See the documentation of the IloMPModeler.column methods for the details of these arguments. Each of these methods returns an object of type IloColumn that contains information about how to add a new variable to the modeling object for which the IloMPModeler.column method has been called.

The column objects can then be linked to an aggregate column object by the method IloColumn.and. This aggregate object contains information about how to add a new variable to all of the modeling objects represented by its parts. If the new variable is to be installed in only one modeling object, there is no need to use the method and.

The column object constructed this way is now ready to be used to create a new variable. This is done by passing the column object as an argument to the constructor methods for variables, for example IloMPModeler.numVar() or IloMPModeler.intVar(). The newly created variable will immediately be part of the existing modeling objects that have been used to construct the column object.

The following example function shows how to create a variable with bounds 0 (zero) and 1 (one) and how to install it in an objective and a range constraint, with linear coefficients 2 and 3:

  IloNumVar newColumn(IloMPModeler modeler, IloObjective obj, IloRange rng) {
    IloColumn objcol = modeler.column(obj, 2.0);
    IloColumn rngcol = modeler.column(rng, 3.0);
    return modeler.numVar(objcol.and(rngcol), 0.0, 1.0);
  }
  

See Also:

IloMPModeler.column(IloObjective, double), IloMPModeler.column(IloLPMatrix), IloMPModeler.column(IloRange, double), IloMPModeler.numVar(IloColumn, double, double), IloMPModeler.intVar(IloColumn, int, int), IloMPModeler.boolVar(IloColumn), IloMPModeler.semiContVar(IloColumn, double, double, IloNumVarType)

Constructor Summary

IloColumn()

Method Summary

IloColumn

and(IloColumn column) Links two column objects.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IloColumn

public IloColumn()

Method Detail

and

public IloColumn and(IloColumn column)

Links two column objects.

When you use the returned column object for constructing a new variable, the new variable will be installed in the modeling objects handled by the invoking column object as well as the modeling objects handled by the column passed as the argument column.

Parameters:

column - The column object to be linked with the invoking column.

Returns:

A column object defining the addition of a newly created variable to the modeling objects handled by the invoking column and to the modeling objects handled by the argument column.