Package org.sosy_lab.common.rationals

Class LinearExpression<T>

java.lang.Object

org.sosy_lab.common.rationals.LinearExpression<T>

All Implemented Interfaces:

Iterable<Map.Entry<T,Rational>>

@Immutable(containerOf="T")
public final class LinearExpression<T>
extends Object
implements Iterable<Map.Entry<T,Rational>>

Simple sparse implementation for homogeneous linear expression of the form $\Sigma a_i x_i$, where $x_i$ is a set of variables and $a_i$ is a set of constants.

Every constant stored has to have a non-zero value.

Method Summary

Modifier and Type	Method	Description
LinearExpression<T>	add(LinearExpression<T> other)	Add other linear expression.
Optional<Rational>	divide(LinearExpression<T> other)	Returns a iff other.multByConst(a) == this, Optional.absent() if no such constant exists.
static <T> LinearExpression<T>	empty()	Creates an empty linear expression.
boolean	equals(@Nullable Object object)
Rational	getCoeff(T variable)
ImmutableMap<T,Rational>	getMap()	Returns the underlying stored map.
int	hashCode()
boolean	isEmpty()
boolean	isIntegral()	Returns whether all coefficients are integral.
Iterator<Map.Entry<T,Rational>>	iterator()
static <T> LinearExpression<T>	monomial(T var, Rational coeff)	Return a monomial with a variable var and a coefficient coeff.
LinearExpression<T>	multByConst(Rational constant)	Multiply the linear expression by constant.
LinearExpression<T>	negate()	Negate the linear expression.
static <T> LinearExpression<T>	ofVariable(T var)	Create a monomial consisting of variable var with a coefficient of one.
static <T> LinearExpression<T>	pair(T var, Rational coeff)	Deprecated. Use monomial(T, org.sosy_lab.common.rationals.Rational) instead.
int	size()	Returns number of variables with non-zero coefficients.
LinearExpression<T>	sub(LinearExpression<T> other)	Subtract other linear expression.
String	toString()	Returns a pretty-printed form of the linear expression.
static void	writeMonomial(String varSerialized, Rational coeff, StringBuilder b)	Pretty-print monomial to the given StringBuilder.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Details

empty

public static <T> LinearExpression<T> empty()

Creates an empty linear expression.

pair

@Deprecated
@InlineMe(replacement="LinearExpression.monomial(var, coeff)",
          imports="org.sosy_lab.common.rationals.LinearExpression")
public static <T> LinearExpression<T> pair(T var,
 Rational coeff)

Deprecated.

Use monomial(T, org.sosy_lab.common.rationals.Rational) instead.

Return a monomial with a variable var and a coefficient coeff.

monomial

public static <T> LinearExpression<T> monomial(T var,
 Rational coeff)

Return a monomial with a variable var and a coefficient coeff.

ofVariable

public static <T> LinearExpression<T> ofVariable(T var)

Create a monomial consisting of variable var with a coefficient of one.

add

public LinearExpression<T> add(LinearExpression<T> other)

Add other linear expression.

sub

public LinearExpression<T> sub(LinearExpression<T> other)

Subtract other linear expression.

multByConst

public LinearExpression<T> multByConst(Rational constant)

Multiply the linear expression by constant.

negate

public LinearExpression<T> negate()

Negate the linear expression.

getCoeff

public Rational getCoeff(T variable)

size

public int size()

Returns number of variables with non-zero coefficients.

isEmpty

public boolean isEmpty()

isIntegral

public boolean isIntegral()

Returns whether all coefficients are integral.

divide

public Optional<Rational> divide(LinearExpression<T> other)

Returns a iff other.multByConst(a) == this, Optional.absent() if no such constant exists.

iterator

public Iterator<Map.Entry<T,Rational>> iterator()

Specified by:

iterator in interface Iterable<T>

getMap

public ImmutableMap<T,Rational> getMap()

Returns the underlying stored map.

toString

public String toString()

Returns a pretty-printed form of the linear expression. E. g. -x + 2y + z

Overrides:

toString in class Object

writeMonomial

public static void writeMonomial(String varSerialized,
 Rational coeff,
 StringBuilder b)

Pretty-print monomial to the given StringBuilder.

equals

public boolean equals(@Nullable Object object)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object