Package org.apache.commons.numbers.primes

Class Primes

java.lang.Object

org.apache.commons.numbers.primes.Primes

public final class Primes
extends Object

Methods related to prime numbers in the range of int.

• primality test
• prime number generation
• factorization

Method Summary

Modifier and Type	Method	Description
static boolean	isPrime(int n)	Primality test: tells if the argument is a (provable) prime or not.
static int	nextPrime(int n)	Return the smallest prime greater than or equal to n.
static List<Integer>	primeFactors(int n)	Prime factors decomposition.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

isPrime

public static boolean isPrime(int n)

Primality test: tells if the argument is a (provable) prime or not.

It uses the Miller-Rabin probabilistic test in such a way that a result is guaranteed: it uses the firsts prime numbers as successive base (see Handbook of applied cryptography by Menezes, table 4.1).

Parameters:

n - Number to test.

Returns:

true if n is prime. All numbers < 2 return false.

nextPrime

public static int nextPrime(int n)

Return the smallest prime greater than or equal to n.

Parameters:

n - Positive number.

Returns:

the smallest prime greater than or equal to n.

Throws:

IllegalArgumentException - if n < 0.

primeFactors

public static List<Integer> primeFactors(int n)

Prime factors decomposition.

Parameters:

n - Number to factorize: must be ≥ 2.

Returns:

the list of prime factors of n.

Throws:

IllegalArgumentException - if n < 2.