Module ojalgo

Package org.ojalgo.optimisation

Class Variable

java.lang.Object

org.ojalgo.optimisation.ModelEntity<Variable>

org.ojalgo.optimisation.Variable

All Implemented Interfaces:

Comparable<Variable>, Optimisation, Optimisation.Constraint, Optimisation.Objective

public final class Variable
extends ModelEntity<Variable>

Variable represents a decision variable in an optimization model.

Each variable has a unique index in the model and can have:

• Lower and upper bounds (constraints)
• A contribution weight in the objective function
• An integer or continuous domain
• A current value

Variables can be configured as:

• Binary (0-1 integer variables)
• Integer (whole number values only)
• Continuous (any value within bounds)
• Fixed (equal lower and upper bounds)
• Unbounded (no effective limits)

As a subclass of ModelEntity, a Variable can function both as a constraint (through lower/upper bounds) and as an objective function component (through its contribution weight).

Variables are typically created and managed through ExpressionsBasedModel, which assigns their indices and incorporates them into the optimization problem.

Author:

apete

Nested Class Summary

Nested classes/interfaces inherited from interface org.ojalgo.optimisation.Optimisation

Optimisation.Constraint, Optimisation.ConstraintType, Optimisation.Integration<M extends Optimisation.Model,S extends Optimisation.Solver>, Optimisation.Model, Optimisation.Objective, Optimisation.Options, Optimisation.ProblemStructure, Optimisation.Result, Optimisation.Sense, Optimisation.Solver, Optimisation.State

Method Summary

Modifier and Type	Method	Description
void	addTo(Expression target, BigDecimal scale)	Add this (Variable or Expression) to another Expression, scaled by a factor.
protected void	appendMiddlePart(StringBuilder builder, NumberContext display)
Variable	binary()	See isBinary().
int	compareTo(Variable obj)
protected void	destroy()
boolean	equals(Object obj)
BigDecimal	getLowerSlack()
BigDecimal	getUpperSlack()
BigDecimal	getValue()
int	hashCode()
Variable	integer()
Variable	integer(boolean integer)	See isInteger().
boolean	isBinary()	Variable can only be 0 or 1.
boolean	isInteger()	Is this entity (all involved variables) integer?
boolean	isNegative()	The range includes something invalid input: '<' 0.0
boolean	isPositive()	The range includes something > 0.0
boolean	isValueSet()
Variable	lower(Comparable<?> lower)	Extremely large (absolute value) values are treated as "no limit" (null) and extremely small values are treated as exactly 0.0, unless the input number type is BigDecimal.
BigDecimal	quantifyContribution()
Variable	relax()
void	setInteger(boolean integer)
void	setValue(Comparable<?> value)
Variable	upper(Comparable<?> upper)	Extremely large (absolute value) values are treated as "no limit" (null) and extremely small values are treated as exactly 0.0, unless the input number type is BigDecimal.
protected boolean	validate(BigDecimal value, NumberContext context, BasicLogger appender)
Variable	value(BigDecimal value)

Methods inherited from class org.ojalgo.optimisation.ModelEntity

adjust, appendLeftPart, appendRightPart, getAdjustmentExponent, getAdjustmentFactor, getContributionWeight, getLowerLimit, getLowerLimit, getLowerLimit, getName, getUpperLimit, getUpperLimit, getUpperLimit, isConstraint, isContributionWeightSet, isEqualityConstraint, isLowerConstraint, isLowerLimitSet, isObjective, isUpperConstraint, isUpperLimitSet, level, level, level, lower, lower, reverseAdjustment, shift, toAdjusted, toString, toUnadjusted, upper, upper, validate, weight, weight, weight

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Details

addTo

public void addTo(Expression target,
 BigDecimal scale)

Description copied from class: ModelEntity

Add this (Variable or Expression) to another Expression, scaled by a factor.

Specified by:

addTo in class ModelEntity<Variable>

Parameters:

target - The target Expression

scale - The scaling factor

binary

public Variable binary()

See isBinary().

See Also:

• ModelEntity.getUpperLimit()
• isInteger()
• isBinary()

compareTo

public int compareTo(Variable obj)

equals

public boolean equals(Object obj)

Overrides:

equals in class ModelEntity<Variable>

getLowerSlack

public BigDecimal getLowerSlack()

getUpperSlack

public BigDecimal getUpperSlack()

getValue

public BigDecimal getValue()

hashCode

public int hashCode()

Overrides:

hashCode in class ModelEntity<Variable>

integer

public Variable integer()

integer

public Variable integer(boolean integer)

See isInteger().

isBinary

public boolean isBinary()

Variable can only be 0 or 1.

isInteger

public boolean isInteger()

Description copied from class: ModelEntity

Is this entity (all involved variables) integer?

Specified by:

isInteger in class ModelEntity<Variable>

Returns:

true if this is an integer variable, otherwise false

isNegative

public boolean isNegative()

The range includes something invalid input: '<' 0.0

isPositive

public boolean isPositive()

The range includes something > 0.0

isValueSet

public boolean isValueSet()

lower

public Variable lower(Comparable<?> lower)

Description copied from class: ModelEntity

Extremely large (absolute value) values are treated as "no limit" (null) and extremely small values are treated as exactly 0.0, unless the input number type is BigDecimal. BigDecimal values are always used as they are.

Overrides:

lower in class ModelEntity<Variable>

quantifyContribution

public BigDecimal quantifyContribution()

relax

public Variable relax()

setInteger

public void setInteger(boolean integer)

setValue

public void setValue(Comparable<?> value)

upper

public Variable upper(Comparable<?> upper)

Description copied from class: ModelEntity

Extremely large (absolute value) values are treated as "no limit" (null) and extremely small values are treated as exactly 0.0, unless the input number type is BigDecimal. BigDecimal values are always used as they are.

Overrides:

upper in class ModelEntity<Variable>

value

public Variable value(BigDecimal value)

appendMiddlePart

protected void appendMiddlePart(StringBuilder builder,
 NumberContext display)

Overrides:

appendMiddlePart in class ModelEntity<Variable>

destroy

protected void destroy()

Overrides:

destroy in class ModelEntity<Variable>

validate

protected boolean validate(BigDecimal value,
 NumberContext context,
 BasicLogger appender)

Overrides:

validate in class ModelEntity<Variable>