Package org.tweetyproject.math.term

Class Variable

java.lang.Object

org.tweetyproject.math.term.Term

org.tweetyproject.math.term.Variable

Direct Known Subclasses:

BinaryVariable, FloatVariable, IntegerVariable

public abstract class Variable
extends Term

This class models a variable as a mathematical term.

Author:

Matthias Thimm

Constructor Summary

Constructors

Constructor	Description
Variable(String name)	Creates a new variable with the given name.
Variable(String name, boolean isPositive)	Creates a new variable with the given name.
Variable(String name, double lowerBound, double upperBound)	Creates a new variable with the given name and bounds.

Method Summary

Modifier and Type	Method	Description
void	collapseAssociativeOperations()	This method collapses all associative operations appearing in this term, e.g.
Term	derive(Variable v)	Differentiates the term with respect to the given variable.
boolean	equals(Object obj)
void	expandAssociativeOperations()	This method expands all associative operations appearing in this term, e.g.
Set<AbsoluteValue>	getAbsoluteValues()	Returns all absolute values of this term.
double	getLowerBound()	Returns the lower bound of this variable.
Set<Maximum>	getMaximums()	Returns all maximums of this term.
Set<Minimum>	getMinimums()	Returns all minimums of this term.
String	getName()	Returns the name of this variable.
Set<Product>	getProducts()	Returns all products of this term.
Set<Sum>	getSums()	Returns all sums of this term.
List<Term>	getTerms()	Getter Terms
double	getUpperBound()	Returns the upper bound of this variable.
Set<Variable>	getVariables()	Returns all variables in this term.
int	hashCode()
boolean	isContinuous(Variable v)	Checks whether this term is continuous in v.
boolean	isPositive()	Checks whether this variables should be positive.
Term	replaceTerm(Term toSubstitute, Term substitution)	Replaces each occurrence of "toSubstitute" by "substitution" and return the new term.
Term	simplify()	Simplifies this term in an equivalent way: - Replaces products that contain a zero by the constant zero - Removes a term one from products - Removes a term zero from sums - Aggregates constants in sums, products, and minimums - Evaluates functional terms on constants - Simplifies fractions where possible.
Sum	toLinearForm()	Converts this term into a linear normal form, i.e.
Sum	toQuadraticForm()	Return a quadratic form
String	toString()
Constant	value()	Computes the actual value of this term if it contains no variables.

Methods inherited from class org.tweetyproject.math.term.Term

add, doubleValue, evaluateMatrix, evaluateVector, evaluateVector, isContinuous, isInteger, isLinear, isQuadratic, min, minus, mult, replaceAllTerms, replaceAllTerms

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Details

Variable

public Variable(String name)

Creates a new variable with the given name.

Parameters:

name - the name of this variable.

Variable

public Variable(String name,
 boolean isPositive)

Creates a new variable with the given name.

Parameters:

name - the name of this variable.

isPositive - whether this variables should be positive.

Variable

public Variable(String name,
 double lowerBound,
 double upperBound)

Creates a new variable with the given name and bounds.

Parameters:

name - the name of this variable.

lowerBound - the lower bound of the variable.

upperBound - the upper bound of the variable.

Method Details

isPositive

public boolean isPositive()

Checks whether this variables should be positive.

Returns:

"true" if this variables should be positive.

getUpperBound

public double getUpperBound()

Returns the upper bound of this variable.

Returns:

the upper bound of this variable.

getLowerBound

public double getLowerBound()

Returns the lower bound of this variable.

Returns:

the lower bound of this variable.

value

public Constant value()

Description copied from class: Term

Computes the actual value of this term if it contains no variables.

Specified by:

value in class Term

Returns:

the value of this term, either a float or an integer.

getName

public String getName()

Returns the name of this variable.

Returns:

the name of this variable.

getVariables

public Set<Variable> getVariables()

Description copied from class: Term

Returns all variables in this term.

Specified by:

getVariables in class Term

Returns:

all variables in this term.

getProducts

public Set<Product> getProducts()

Description copied from class: Term

Returns all products of this term.

Specified by:

getProducts in class Term

Returns:

all products of this term.

getSums

public Set<Sum> getSums()

Description copied from class: Term

Returns all sums of this term.

Specified by:

getSums in class Term

Returns:

all sums of this term.

getMinimums

public Set<Minimum> getMinimums()

Description copied from class: Term

Returns all minimums of this term.

Specified by:

getMinimums in class Term

Returns:

all minimums of this term.

getMaximums

public Set<Maximum> getMaximums()

Description copied from class: Term

Returns all maximums of this term.

Specified by:

getMaximums in class Term

Returns:

all maximums of this term.

getAbsoluteValues

public Set<AbsoluteValue> getAbsoluteValues()

Description copied from class: Term

Returns all absolute values of this term.

Specified by:

getAbsoluteValues in class Term

Returns:

all absolute values of this term.

replaceTerm

public Term replaceTerm(Term toSubstitute,
 Term substitution)

Description copied from class: Term

Replaces each occurrence of "toSubstitute" by "substitution" and return the new term.

Specified by:

replaceTerm in class Term

Parameters:

toSubstitute - the term to be substituted

substitution - the new term

Returns:

this term where "toSubstitute" is replaced by "substitution"

collapseAssociativeOperations

public void collapseAssociativeOperations()

Description copied from class: Term

This method collapses all associative operations appearing in this term, e.g. every min{min{a,b},c} becomes min{a,b,c}.

Specified by:

collapseAssociativeOperations in class Term

expandAssociativeOperations

public void expandAssociativeOperations()

Description copied from class: Term

This method expands all associative operations appearing in this term, e.g. every min{a,b,c} becomes min{min{a,b},c}.

Specified by:

expandAssociativeOperations in class Term

isContinuous

public boolean isContinuous(Variable v)

Description copied from class: Term

Checks whether this term is continuous in v.

Specified by:

isContinuous in class Term

Parameters:

v - a variable

Returns:

"true" iff this term is continuous in v.

toLinearForm

public Sum toLinearForm()
                 throws IllegalArgumentException

Description copied from class: Term

Converts this term into a linear normal form, i.e. into a sum of products of a constant and a variable.

Specified by:

toLinearForm in class Term

Returns:

a term in linear normal form.

Throws:

IllegalArgumentException - if this term cannot be converted into a linear normal form.

toQuadraticForm

public Sum toQuadraticForm()
                    throws IllegalArgumentException

Description copied from class: Term

Return a quadratic form

Specified by:

toQuadraticForm in class Term

Returns:

a quadratic form

Throws:

IllegalArgumentException - error

derive

public Term derive(Variable v)

Description copied from class: Term

Differentiates the term with respect to the given variable.

Specified by:

derive in class Term

Parameters:

v - a variable.

Returns:

the derivation of this term wrt. the given variable.

simplify

public Term simplify()

Description copied from class: Term

Simplifies this term in an equivalent way:
- Replaces products that contain a zero by the constant zero
- Removes a term one from products
- Removes a term zero from sums
- Aggregates constants in sums, products, and minimums
- Evaluates functional terms on constants
- Simplifies fractions where possible.

Specified by:

simplify in class Term

Returns:

the simplified term.

getTerms

public List<Term> getTerms()

Description copied from class: Term

Getter Terms

Specified by:

getTerms in class Term

Returns:

List of Terms

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Specified by:

toString in class Term