ilog.concert
Class IloColumnArray

java.lang.Object
  |
  +--ilog.concert.IloColumnArray

public abstract class IloColumnArray

extends java.lang.Object

Objects of the class IloColumnArray are used to create an array of variables using column-wise modeling. In column-wise modeling, newly constructed variables are inserted into existing modeling objects. The term column-wise comes from linear programing, where the constraints are typically represented as a matrix. Adding new variables to the optimization problem corresponds to adding columns to the constraint matrix.

This is the procedure for column-wise modeling:

Start with the set of modeling objects of these classes

• IloObjective,
• IloRange, and
• IloLPMatrix

to which you want to add new variables.

For each of these objects call IloMPModeler.columnArray, with the object as a parameter, along with the other parameters needed to install an array of new variables in the existing modeling objects. See the IloMPModeler.columnArray() documentation for details of these parameters.

The IloColumnArray objects can then be linked to an aggregate IloColumnArray object with the method IloColumnArray.and, which will include all the individual objects. If the new variables are to be installed in only one modeling object, there is no need to use the method and.

The IloColumnArray object constructed this way is now ready to be used to create an array of new variables and install them in the existing modeling objects, as described by the IloColumnArray object. This is done by passing the IloColumnArray object as a parameter to the constructor methods for arrays of variables, for example IloMPModeler.numVarArray or IloMPModeler.intVarArray. The newly created variables will immediately be part of the existing modeling objects that have been used for constructing the IloColumnArray object.

The following example shows how to create an array of two new variables with the bounds 0 and 1 and how to install them in an objective and a range constraint, with linear coefficients all set to 1:

  IloNumVar[] newColumns(IloMPModeler modeler, IloObjective obj, IloRange rng) {
    double[] ones = {1.0, 1.0};
    IloColumnArray objcol = modeler.columnArray(obj, ones);
    IloColumnArray rngcol = modeler.columnArray(rng, ones);
    return modeler.numVarArray(objcol.and(rngcol), 0.0, 1.0);
  }
  

See Also:

IloMPModeler.columnArray(IloObjective, double[]), IloMPModeler.columnArray(IloLPMatrix, int, int[][], double[][]), IloMPModeler.columnArray(IloRange, double[]), IloMPModeler.numVarArray(IloColumnArray, double[], double[]), IloMPModeler.intVarArray(IloColumnArray, int[], int[]), IloMPModeler.semiContVarArray(IloColumnArray, double[], double[], IloNumVarType[])

Nested Class Summary

static class

IloColumnArray.SizeMismatchException An exception that indicates a mismatched number of variables.

Constructor Summary

IloColumnArray()

Method Summary

abstract int

getSize() Returns the number of variables that are created by the invoking IloColumnArray object.

Methods inherited from class java.lang.Object

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

Constructor Detail

IloColumnArray

public IloColumnArray()

Method Detail

getSize

public abstract int getSize()

Returns the number of variables that are created by the invoking IloColumnArray object. Every IloColumnArray object is suitable for constructing a variable array of a specific length. The length must be the same in each IloColumnArray when combining IloColumnArray objects with the method and.

Returns:

The number of variables created by the invoking IloColumnArray object.