org.spaceroots.mantissa.algebra
Class RationalNumber

java.lang.Object
  org.spaceroots.mantissa.algebra.RationalNumber

All Implemented Interfaces:

Serializable

public class RationalNumber

extends Object

implements Serializable

This class implements reduced rational numbers.

Instances of this class are immutable.

Version:

$Id: RationalNumber.java 1711 2006-12-13 21:27:51Z luc $

Author:

L. Maisonobe

See Also:

Serialized Form

Field Summary

static RationalNumber	ONE One as a rational numer.
static RationalNumber	ZERO Zero as a rational numer.

Constructor Summary

RationalNumber()
Simple constructor.

RationalNumber(BigInteger i)
Simple constructor.

RationalNumber(BigInteger numerator, BigInteger denominator)
Simple constructor.

RationalNumber(long l)
Simple constructor.

RationalNumber(long numerator, long denominator)
Simple constructor.

Method Summary

static RationalNumber	abs(RationalNumber r) Get the absolute value of a rational number.
RationalNumber	add(BigInteger l) Add an integer to the instance.
RationalNumber	add(long l) Add an integer to the instance.
RationalNumber	add(RationalNumber r) Add a rational number to the instance.
RationalNumber	divide(BigInteger l) Divide the instance by an integer.
RationalNumber	divide(long l) Divide the instance by an integer.
RationalNumber	divide(RationalNumber r) Divide the instance by a rational number.
double	doubleValue() Return the double value of the instance.
boolean	equals(Object o) Check if the instance is equal to another rational number.
BigInteger	getDenominator() Get the denominator.
BigInteger	getNumerator() Get the numerator.
int	hashCode() Returns a hash code value for the object.
RationalNumber	invert() Invert the instance.
boolean	isInteger() Check if the number is integer.
boolean	isNegative() Check if the number is negative.
boolean	isOne() Check if the number is one.
boolean	isZero() Check if the number is zero.
RationalNumber	multiply(BigInteger l) Multiply the instance by an integer.
RationalNumber	multiply(long l) Multiply the instance by an integer.
RationalNumber	multiply(RationalNumber r) Multiply the instance by a rational number.
RationalNumber	negate() Negate the instance.
RationalNumber	subtract(BigInteger l) Subtract an integer from the instance.
RationalNumber	subtract(long l) Subtract an integer from the instance.
RationalNumber	subtract(RationalNumber r) Subtract a rational number from the instance.
String	toString() Returns a string representation of the rational number.

Methods inherited from class java.lang.Object

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

Field Detail

ZERO

public static final RationalNumber ZERO

Zero as a rational numer.

ONE

public static final RationalNumber ONE

One as a rational numer.

Constructor Detail

RationalNumber

public RationalNumber()

Simple constructor. Build a null rational number

RationalNumber

public RationalNumber(long numerator,
                      long denominator)

Simple constructor. Build a rational number from a numerator and a denominator.

Parameters:

numerator - numerator of the rational number

denominator - denominator of the rational number

Throws:

ArithmeticException - if the denominator is zero

RationalNumber

public RationalNumber(BigInteger numerator,
                      BigInteger denominator)

Simple constructor. Build a rational number from a numerator and a denominator.

Parameters:

numerator - numerator of the rational number

denominator - denominator of the rational number

Throws:

ArithmeticException - if the denominator is zero

RationalNumber

public RationalNumber(long l)

Simple constructor. Build a rational number from a single integer

Parameters:

l - value of the rational number

RationalNumber

public RationalNumber(BigInteger i)

Simple constructor. Build a rational number from a single integer

Parameters:

i - value of the rational number

Method Detail

negate

public RationalNumber negate()

Negate the instance.

Returns:

a new rational number, opposite to the isntance

add

public RationalNumber add(long l)

Add an integer to the instance.

Parameters:

l - integer to add

Returns:

a new rational number which is the sum of the instance and l

add

public RationalNumber add(BigInteger l)

Add an integer to the instance.

Parameters:

l - integer to add

Returns:

a new rational number which is the sum of the instance and l

add

public RationalNumber add(RationalNumber r)

Add a rational number to the instance.

Parameters:

r - rational number to add

Returns:

a new rational number which is the sum of the instance and r

subtract

public RationalNumber subtract(long l)

Subtract an integer from the instance.

Parameters:

l - integer to subtract

Returns:

a new rational number which is the difference the instance minus l

subtract

public RationalNumber subtract(BigInteger l)

Subtract an integer from the instance.

Parameters:

l - integer to subtract

Returns:

a new rational number which is the difference the instance minus l

subtract

public RationalNumber subtract(RationalNumber r)

Subtract a rational number from the instance.

Parameters:

r - rational number to subtract

Returns:

a new rational number which is the difference the instance minus r

multiply

public RationalNumber multiply(long l)

Multiply the instance by an integer.

Parameters:

l - integer to multiply by

Returns:

a new rational number which is the produc of the instance by l

multiply

public RationalNumber multiply(BigInteger l)

Multiply the instance by an integer.

Parameters:

l - integer to multiply by

Returns:

a new rational number which is the produc of the instance by l

multiply

public RationalNumber multiply(RationalNumber r)

Multiply the instance by a rational number.

Parameters:

r - rational number to multiply the instance with

Returns:

a new rational number which is the product of the instance and r

divide

public RationalNumber divide(long l)

Divide the instance by an integer.

Parameters:

l - integer to divide by

Returns:

a new rational number which is the quotient of the instance by l

Throws:

ArithmeticException - if l is zero

divide

public RationalNumber divide(BigInteger l)

Divide the instance by an integer.

Parameters:

l - integer to divide by

Returns:

a new rational number which is the quotient of the instance by l

Throws:

ArithmeticException - if l is zero

divide

public RationalNumber divide(RationalNumber r)

Divide the instance by a rational number.

Parameters:

r - rational number to divide by

Returns:

a new rational number which is the quotient of the instance by r

Throws:

ArithmeticException - if r is zero

invert

public RationalNumber invert()

Invert the instance.

Returns:

the inverse of the instance

Throws:

ArithmeticException - if the instance is zero

getNumerator

public BigInteger getNumerator()

Get the numerator.

Returns:

the signed numerator

getDenominator

public BigInteger getDenominator()

Get the denominator.

Returns:

the denominator (always positive)

isZero

public boolean isZero()

Check if the number is zero.

Returns:

true if the number is zero

isOne

public boolean isOne()

Check if the number is one.

Returns:

true if the number is one

isInteger

public boolean isInteger()

Check if the number is integer.

Returns:

true if the number is an integer

isNegative

public boolean isNegative()

Check if the number is negative.

Returns:

true if the number is negative

abs

public static RationalNumber abs(RationalNumber r)

Get the absolute value of a rational number.

Parameters:

r - rational number from which we want the absolute value

Returns:

a new rational number which is the absolute value of r

doubleValue

public double doubleValue()

Return the double value of the instance.

Returns:

the double value of the instance

equals

public boolean equals(Object o)

Check if the instance is equal to another rational number. Equality here is having the same value.

Returns:

true if the object is a rational number which has the same value as the instance

hashCode

public int hashCode()

Returns a hash code value for the object. The hash code value is computed from the reduced numerator and denominator, hence equal rational numbers have the same hash code, as required by the method specification.

Returns:

a hash code value for this object.

toString

public String toString()

Returns a string representation of the rational number. The representation is reduced: there is no common factor left between the numerator and the denominator. The '/' character and the denominator are displayed only if the denominator is not one. The sign is on the numerator.

Returns:

string representation of the rational number