Package eu.bandm.tools.ops

Class PrimeFactors

java.lang.Object

eu.bandm.tools.ops.PrimeFactors

public class PrimeFactors
extends Object

Immutable prime factor combinations as representation of Rationals, thus with positive or negative exponents. Internally they maintain a Map from bases to exponents. Bases with exponent==0 are removed from the maps.

Field Summary

Fields

Modifier and Type	Field	Description
static final Comparator<PrimeFactors>	byIntValue
static final Comparator<PrimeFactors>	byRatValue
protected static Map<Integer,PrimeFactors>	cache_int
protected static Map<Rational,PrimeFactors>	cache_rat
static final PrimeFactors	ONE
static final PrimeFactors	TWO
static final int	UNCOMPARABLE

Method Summary

Modifier and Type	Method	Description
(package private) static void	__clearCaches()
PrimeFactors	add(int base, int exp)	Return an instance with the base and exponent overwritten.
int	cmp(PrimeFactors other)	Returns -1/0/+1 for inclusion or equality, negative exponents are smaller than positives, and returns a different int (here UNCOMPARABLE) iff not comparable.
int	complexity()
int	countPrimes()
PrimeFactors	divide(PrimeFactors b)	Subtract exponents, ie.
boolean	equals(PrimeFactors b)
boolean	equals(Object b)
PrimeFactors	getDenominator()
int	getExponent(int p)
PrimeFactors	getNumerator()
int	hashCode()
PrimeFactors	integerGCD(PrimeFactors b)	Return an instance with the more negative exponents of both arguments.
PrimeFactors	integerLCM(PrimeFactors b)	Return an instance with the more positive exponents of both arguments.
int	intValue()	Return the integer value.
boolean	isInteger()	evident
boolean	isIntegerMultipleOf(PrimeFactors b)	Returns whether arg is a factor of this
boolean	isOne()	evident
boolean	isPowerOf(int b)	Whether this is a power (possibly with an exponent ==0) of the one single basis.
static boolean	isPrime(int i)	Whether the argument is a prime number >=1.
static boolean	isPrimePower(int i)	Whether the argument is a power (possibly with an exponent ==0) of only one single basis.
static boolean	isPrimePower(Rational r)	Whether the argument is a power (possibly with an exponent ==0) of only one single basis.
PrimeFactors	multiply(PrimeFactors b)	Add exponents, ie.
static PrimeFactors	of(int value)	Central service provider and also the implementation: Calculate the prime factors, cache and return them.
static PrimeFactors	of(Rational rat)	Returns the prime factor map for the given value.
static PrimeFactors	of(BigInteger bi)	Central service provider: Calculate the prime factors and return them as an immutable instance.
SortedSet<Integer>	primes()
Rational	ratValue()	Return the rational value.
List<Integer>	simpleFactors(boolean reverse)	Iterate over identic factors seperatedly, like "2, 2, 3, 5, 5", not "4,3,25".
String	toString()
PrimeFactors	with(int base, int exp)	Return an instance with the base and exponent overwritten.
PrimeFactors	without(int p)	Remove basis from domain.

Methods inherited from class java.lang.Object

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

Field Details

UNCOMPARABLE

public static final int UNCOMPARABLE

See Also:

• Constant Field Values

cache_int

protected static Map<Integer,PrimeFactors> cache_int

cache_rat

protected static Map<Rational,PrimeFactors> cache_rat

ONE

public static final PrimeFactors ONE

TWO

public static final PrimeFactors TWO

byRatValue

public static final Comparator<PrimeFactors> byRatValue

byIntValue

public static final Comparator<PrimeFactors> byIntValue

Method Details

__clearCaches

static void __clearCaches()

of

public static PrimeFactors of(BigInteger bi)

Central service provider: Calculate the prime factors and return them as an immutable instance. Works only for BigIntegeres which are representable as int.

Returns:

prime factor map for the given value.

of

public static PrimeFactors of(int value)

Central service provider and also the implementation: Calculate the prime factors, cache and return them.

Returns:

prime factor map for the given value.

of

public static PrimeFactors of(Rational rat)

Returns the prime factor map for the given value. Assumes that Rationals are always normalized

Returns:

the prime factor map for the given value.

toString

public String toString()

Overrides:

toString in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object b)

Overrides:

equals in class Object

equals

public boolean equals(PrimeFactors b)

primes

public SortedSet<Integer> primes()

isIntegerMultipleOf

public boolean isIntegerMultipleOf(PrimeFactors b)

Returns whether arg is a factor of this

isPrime

public static boolean isPrime(int i)

Whether the argument is a prime number >=1. 1 and 2 count as prime.

isPrimePower

public static boolean isPrimePower(int i)

Whether the argument is a power (possibly with an exponent ==0) of only one single basis.

isPrimePower

public static boolean isPrimePower(Rational r)

Whether the argument is a power (possibly with an exponent ==0) of only one single basis.

isPowerOf

public boolean isPowerOf(int b)

Whether this is a power (possibly with an exponent ==0) of the one single basis.

isOne

public boolean isOne()

evident

isInteger

public boolean isInteger()

evident

getExponent

public int getExponent(int p)

Returns:

the exponent for the given base.

countPrimes

public int countPrimes()

Returns:

the number of different bases.

complexity

public int complexity()

Returns:

the number of different factors, which is the sum of the absolute values of all exponents.

intValue

public int intValue()

Return the integer value. If there is no such, ie. some exponent is negative, an IllegalArgumentException is thrown. If "this" was created with an exponent map, this value must be calculated and is stored locally.

ratValue

public Rational ratValue()

Return the rational value. If "this" was created with an exponent map, this value must be calculated and is stored locally iff this is not modifiable.

simpleFactors

public List<Integer> simpleFactors(boolean reverse)

Iterate over identic factors seperatedly, like "2, 2, 3, 5, 5", not "4,3,25".

cmp

public int cmp(PrimeFactors other)

Returns -1/0/+1 for inclusion or equality, negative exponents are smaller than positives, and returns a different int (here UNCOMPARABLE) iff not comparable.

without

public PrimeFactors without(int p)

Remove basis from domain. Works also for arguments which are not valid prime bases.

integerLCM

public PrimeFactors integerLCM(PrimeFactors b)

Return an instance with the more positive exponents of both arguments.

integerGCD

public PrimeFactors integerGCD(PrimeFactors b)

Return an instance with the more negative exponents of both arguments.

with

public PrimeFactors with(int base,
 int exp)

Return an instance with the base and exponent overwritten.

Parameters:

base - must be a valid prime basis. ==1 is allowed, but has no effect. Attention: prime check costs.

add

public PrimeFactors add(int base,
 int exp)

Return an instance with the base and exponent overwritten.

Parameters:

base - must be a valid prime basis. ==1 is allowed, but has no effect.

exp - ==0 works also with invalid bases and has no effect (= returns this)

See Also:

• with(int,int)

divide

public PrimeFactors divide(PrimeFactors b)

Subtract exponents, ie. divide values.

multiply

public PrimeFactors multiply(PrimeFactors b)

Add exponents, ie. multiply values.

getDenominator

public PrimeFactors getDenominator()

Returns:

prime factors in denominator, as positive exponents of the original negatives.

getNumerator

public PrimeFactors getNumerator()

Returns:

prime factors in numerators, i.e. all which are originally positive.