org.ojalgo.optimisation

Class Expression

java.lang.Object

org.ojalgo.optimisation.Expression

All Implemented Interfaces:

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

public final class Expression
extends Object

Think of an Expression as one constraint or a component to the objective function. An expression becomes a linear expression as soon as you set a linear factor. Setting a quadratic factor turns it into a quadratic expression. If you set both linear and quadratic factors it is a compound expression, and if you set neither it is an empty expression. Currently the solvers supplied by ojAlgo can only handle linear constraint expressions. The objective function can be linear, quadratic or compound. Empty expressions makes no sense...

An expression is turned into a constraint by setting a lower and/or upper limit. Use ModelEntity.lower(Number), ModelEntity.upper(Number) or ModelEntity.level(Number). An expression is made part of (contributing to) the objective function by setting a contribution weight. Use ModelEntity.weight(Number). The contribution weight can be set to anything except zero (0.0). Often you may just want to set it to one (1.0). Other values can be used to balance multiple expressions contributing to the objective function.

Author:

apete

Nested Class Summary

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

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

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Expression(Expression expressionToCopy, ExpressionsBasedModel destinationModel, boolean deep)

Method Summary

Modifier and Type	Method and Description
Expression	add(Structure1D.IntIndex key, Number value)
Expression	add(Structure2D.IntRowColumn key, Number value)
protected void	appendLeftPart(StringBuilder builder)
protected void	appendMiddlePart(StringBuilder builder)
protected void	appendMiddlePart(StringBuilder builder, Access1D<BigDecimal> currentSolution)
protected void	appendRightPart(StringBuilder builder)
int	compareTo(Expression obj)
Expression	compensate(Set<Structure1D.IntIndex> fixedVariables) Will return an Expression with factors corresponding to fixed variables removed, and lower/upper limits compensated for the fixed part of the expression.
protected void	destroy()
protected void	doIntegerRounding()
boolean	equals(Object obj)
BigDecimal	evaluate(Access1D<BigDecimal> point)
BigDecimal	get(Structure1D.IntIndex key)
BigDecimal	get(Structure2D.IntRowColumn key)
BigDecimal	get(Variable variable)
MatrixStore<Double>	getAdjustedGradient(Access1D<?> point)
MatrixStore<Double>	getAdjustedHessian()
double	getAdjustedLinearFactor(int aVar)
double	getAdjustedLinearFactor(Structure1D.IntIndex key)
double	getAdjustedLinearFactor(Variable aVar)
double	getAdjustedLowerLimit()
double	getAdjustedQuadraticFactor(int aVar1, int aVar2)
double	getAdjustedQuadraticFactor(Structure2D.IntRowColumn key)
double	getAdjustedQuadraticFactor(Variable aVar1, Variable aVar2)
double	getAdjustedUpperLimit()
protected int	getAdjustmentExponent()
double	getAdjustmentFactor()
BigDecimal	getContributionWeight() The weight/factor by which this model entity's value contributes to the objective function - may return null.
Set<Map.Entry<Structure1D.IntIndex,BigDecimal>>	getLinearEntrySet()
Set<Structure1D.IntIndex>	getLinearKeySet()
BigDecimal	getLowerLimit() The lower limit/bound - may return null.
String	getName()
Set<Map.Entry<Structure2D.IntRowColumn,BigDecimal>>	getQuadraticEntrySet()
Set<Structure2D.IntRowColumn>	getQuadraticKeySet()
double	getUnadjustedLowerLimit()
double	getUnadjustedUpperLimit()
BigDecimal	getUpperLimit() The upper limit/bound - may return null.
int	hashCode()
boolean	isAnyLinearFactorNonZero()
boolean	isAnyQuadraticFactorNonZero()
boolean	isConstraint() The Constraint has a lower or an upper limit actually set (possibly both) - it actually is constained.
boolean	isContributionWeightSet()
boolean	isEqualityConstraint() The Constraint has both a lower limit and an upper limit, and they are equal.
boolean	isFunctionCompound()
boolean	isFunctionLinear()
boolean	isFunctionQuadratic()
boolean	isFunctionZero()
boolean	isLinearAndAllBinary()
boolean	isLinearAndAllInteger()
boolean	isLinearAndAnyBinary()
boolean	isLinearAndAnyInteger()
boolean	isLowerConstraint() The Constraint has a lower limit, and the upper limit (if it exists) is different.
boolean	isLowerLimitSet()
boolean	isObjective()
boolean	isUpperConstraint() The Constraint has an upper limit, and the lower limit (if it exists) is different.
boolean	isUpperLimitSet()
ME	level(Number level)
ME	lower(Number 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.
Expression	set(int row, int column, Number value)
Expression	set(int index, Number value)
Expression	set(Structure1D.IntIndex key, Number value)
Expression	set(Structure1D.IntIndex row, Structure1D.IntIndex column, Number value)
Expression	set(Structure2D.IntRowColumn key, Number value)
Expression	set(Variable variable, Number value)
Expression	set(Variable variable1, Variable variable2, Number value)
void	setCompoundFactorsOffset(List<Variable> variables, Access1D<?> point) Will set the quadratic and linear factors to an expression that measures (the square of) the distance from the given point.
void	setLinearFactors(List<Variable> variables, Access1D<?> factors)
void	setLinearFactorsSimple(List<Variable> variables) Will set the linear factors to a simple sum expression - all factors equal 1.0.
void	setQuadraticFactors(List<Variable> variables, Access2D<?> factors)
MultiaryFunction.TwiceDifferentiable<Double>	toFunction()
String	toString()
ME	upper(Number 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(BasicLogger.Printer appender) Validate model parameters, like lower and upper limits.
protected boolean	validate(BigDecimal value, NumberContext context, BasicLogger.Printer appender)
ME	weight(Number weight)

Methods inherited from class java.lang.Object

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

Constructor Detail

Expression

protected Expression(Expression expressionToCopy,
                     ExpressionsBasedModel destinationModel,
                     boolean deep)

Method Detail

add

public Expression add(Structure1D.IntIndex key,
                      Number value)

add

public Expression add(Structure2D.IntRowColumn key,
                      Number value)

compareTo

public int compareTo(Expression obj)

compensate

public Expression compensate(Set<Structure1D.IntIndex> fixedVariables)

Will return an Expression with factors corresponding to fixed variables removed, and lower/upper limits compensated for the fixed part of the expression. Factors corresponding to bilinear variables, where one is fixed and the other is not, are linearized.

Parameters:

fixedVariables - A set of (by the presolver) fixed variable indices

Returns:

The reduced/modified expression

evaluate

public BigDecimal evaluate(Access1D<BigDecimal> point)

get

public BigDecimal get(Structure1D.IntIndex key)

get

public BigDecimal get(Structure2D.IntRowColumn key)

get

public BigDecimal get(Variable variable)

getAdjustedGradient

public MatrixStore<Double> getAdjustedGradient(Access1D<?> point)

getAdjustedHessian

public MatrixStore<Double> getAdjustedHessian()

getAdjustedLinearFactor

public double getAdjustedLinearFactor(int aVar)

getAdjustedLinearFactor

public double getAdjustedLinearFactor(Structure1D.IntIndex key)

getAdjustedLinearFactor

public double getAdjustedLinearFactor(Variable aVar)

getAdjustedQuadraticFactor

public double getAdjustedQuadraticFactor(int aVar1,
                                         int aVar2)

getAdjustedQuadraticFactor

public double getAdjustedQuadraticFactor(Structure2D.IntRowColumn key)

getAdjustedQuadraticFactor

public double getAdjustedQuadraticFactor(Variable aVar1,
                                         Variable aVar2)

getLinearEntrySet

public Set<Map.Entry<Structure1D.IntIndex,BigDecimal>> getLinearEntrySet()

getLinearKeySet

public Set<Structure1D.IntIndex> getLinearKeySet()

getQuadraticEntrySet

public Set<Map.Entry<Structure2D.IntRowColumn,BigDecimal>> getQuadraticEntrySet()

getQuadraticKeySet

public Set<Structure2D.IntRowColumn> getQuadraticKeySet()

isAnyLinearFactorNonZero

public boolean isAnyLinearFactorNonZero()

isAnyQuadraticFactorNonZero

public boolean isAnyQuadraticFactorNonZero()

isFunctionCompound

public boolean isFunctionCompound()

isFunctionLinear

public boolean isFunctionLinear()

isFunctionQuadratic

public boolean isFunctionQuadratic()

isFunctionZero

public boolean isFunctionZero()

isLinearAndAllBinary

public boolean isLinearAndAllBinary()

Returns:

Are all the (linear) variables binary

isLinearAndAllInteger

public boolean isLinearAndAllInteger()

Returns:

Are all the (linear) variables integer

isLinearAndAnyBinary

public boolean isLinearAndAnyBinary()

Returns:

Are any of the (linear) variables binary

isLinearAndAnyInteger

public boolean isLinearAndAnyInteger()

Returns:

Are any of the (linear) variables integer

set

public Expression set(int row,
                      int column,
                      Number value)

set

public Expression set(int index,
                      Number value)

set

public Expression set(Structure1D.IntIndex row,
                      Structure1D.IntIndex column,
                      Number value)

set

public Expression set(Structure1D.IntIndex key,
                      Number value)

set

public Expression set(Structure2D.IntRowColumn key,
                      Number value)

set

public Expression set(Variable variable,
                      Number value)

set

public Expression set(Variable variable1,
                      Variable variable2,
                      Number value)

setCompoundFactorsOffset

public void setCompoundFactorsOffset(List<Variable> variables,
                                     Access1D<?> point)

Will set the quadratic and linear factors to an expression that measures (the square of) the distance from the given point.

Parameters:

variables - The relevant variables

point - The point to measure from

setLinearFactors

public void setLinearFactors(List<Variable> variables,
                             Access1D<?> factors)

setLinearFactorsSimple

public void setLinearFactorsSimple(List<Variable> variables)

Will set the linear factors to a simple sum expression - all factors equal 1.0.

Parameters:

variables - The relevant variables

setQuadraticFactors

public void setQuadraticFactors(List<Variable> variables,
                                Access2D<?> factors)

toFunction

public MultiaryFunction.TwiceDifferentiable<Double> toFunction()

appendMiddlePart

protected void appendMiddlePart(StringBuilder builder,
                                Access1D<BigDecimal> currentSolution)

destroy

protected void destroy()

doIntegerRounding

protected void doIntegerRounding()

equals

public final boolean equals(Object obj)

Overrides:

equals in class Object

See Also:

Object.equals(java.lang.Object)

getAdjustedLowerLimit

public final double getAdjustedLowerLimit()

getAdjustedUpperLimit

public final double getAdjustedUpperLimit()

getAdjustmentFactor

public final double getAdjustmentFactor()

Returns:

Adjusted "1"

getContributionWeight

public final BigDecimal getContributionWeight()

Description copied from interface: Optimisation.Objective

The weight/factor by which this model entity's value contributes to the objective function - may return null.

Specified by:

getContributionWeight in interface Optimisation.Objective

getLowerLimit

public final BigDecimal getLowerLimit()

Description copied from interface: Optimisation.Constraint

The lower limit/bound - may return null.

Specified by:

getLowerLimit in interface Optimisation.Constraint

getName

public final String getName()

getUnadjustedLowerLimit

public final double getUnadjustedLowerLimit()

getUnadjustedUpperLimit

public final double getUnadjustedUpperLimit()

getUpperLimit

public final BigDecimal getUpperLimit()

Description copied from interface: Optimisation.Constraint

The upper limit/bound - may return null.

Specified by:

getUpperLimit in interface Optimisation.Constraint

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

isConstraint

public final boolean isConstraint()

Description copied from interface: Optimisation.Constraint

The Constraint has a lower or an upper limit actually set (possibly both) - it actually is constained.

Specified by:

isConstraint in interface Optimisation.Constraint

isContributionWeightSet

public final boolean isContributionWeightSet()

isEqualityConstraint

public final boolean isEqualityConstraint()

Description copied from interface: Optimisation.Constraint

The Constraint has both a lower limit and an upper limit, and they are equal.

Specified by:

isEqualityConstraint in interface Optimisation.Constraint

isLowerConstraint

public final boolean isLowerConstraint()

Description copied from interface: Optimisation.Constraint

The Constraint has a lower limit, and the upper limit (if it exists) is different.

Specified by:

isLowerConstraint in interface Optimisation.Constraint

isLowerLimitSet

public final boolean isLowerLimitSet()

isObjective

public final boolean isObjective()

Specified by:

isObjective in interface Optimisation.Objective

Returns:

true if this Objective has a non zero contribution weight - it actually is contributing to the objective function.

isUpperConstraint

public final boolean isUpperConstraint()

Description copied from interface: Optimisation.Constraint

The Constraint has an upper limit, and the lower limit (if it exists) is different.

Specified by:

isUpperConstraint in interface Optimisation.Constraint

isUpperLimitSet

public final boolean isUpperLimitSet()

level

public final ME level(Number level)

See Also:

getLowerLimit(), getUpperLimit()

lower

public ME lower(Number 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 values are always used as they are.

toString

public final String toString()

Overrides:

toString in class Object

upper

public ME upper(Number 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. BigDecimal values are always used as they are.

weight

public final ME weight(Number weight)

See Also:

getContributionWeight()

appendLeftPart

protected void appendLeftPart(StringBuilder builder)

appendMiddlePart

protected void appendMiddlePart(StringBuilder builder)

appendRightPart

protected void appendRightPart(StringBuilder builder)

getAdjustmentExponent

protected final int getAdjustmentExponent()

validate

protected final boolean validate(BasicLogger.Printer appender)

Validate model parameters, like lower and upper limits. Does not validate the solution/value.

validate

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