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MATH-1416: Remove Primes from commons-math as it have been moved to commons-numbers

This commit is contained in:
Ray DeCampo 2017-09-16 13:17:40 -04:00
parent 9a3b7e4797
commit ae162d7762
2 changed files with 0 additions and 300 deletions
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126
src/main/java/org/apache/commons/math4/primes/Primes.java
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.math4.primes;
import org.apache.commons.math4.exception.MathIllegalArgumentException;
import org.apache.commons.math4.exception.util.LocalizedFormats;
import java.util.List;
/**
* Methods related to prime numbers in the range of <code>int</code>:
* <ul>
* <li>primality test</li>
* <li>prime number generation</li>
* <li>factorization</li>
* </ul>
*
* @since 3.2
*/
public class Primes {
/**
* Hide utility class.
*/
private Primes() {
}
/**
* Primality test: tells if the argument is a (provable) prime or not.
* <p>
* 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).
*
* @param n number to test.
* @return true if n is prime. (All numbers &lt; 2 return false).
*/
public static boolean isPrime(int n) {
if (n < 2) {
return false;
}
for (int p : SmallPrimes.PRIMES) {
if (0 == (n % p)) {
return n == p;
}
}
return SmallPrimes.millerRabinPrimeTest(n);
}
/**
* Return the smallest prime greater than or equal to n.
*
* @param n a positive number.
* @return the smallest prime greater than or equal to n.
* @throws MathIllegalArgumentException if n &lt; 0.
*/
public static int nextPrime(int n) {
if (n < 0) {
throw new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL, n, 0);
}
if (n == 2) {
return 2;
}
n |= 1;//make sure n is odd
if (n == 1) {
return 2;
}
if (isPrime(n)) {
return n;
}
// prepare entry in the +2, +4 loop:
// n should not be a multiple of 3
final int rem = n % 3;
if (0 == rem) { // if n % 3 == 0
n += 2; // n % 3 == 2
} else if (1 == rem) { // if n % 3 == 1
// if (isPrime(n)) return n;
n += 4; // n % 3 == 2
}
while (true) { // this loop skips all multiple of 3
if (isPrime(n)) {
return n;
}
n += 2; // n % 3 == 1
if (isPrime(n)) {
return n;
}
n += 4; // n % 3 == 2
}
}
/**
* Prime factors decomposition
*
* @param n number to factorize: must be &ge; 2
* @return list of prime factors of n
* @throws MathIllegalArgumentException if n &lt; 2.
*/
public static List<Integer> primeFactors(int n) {
if (n < 2) {
throw new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL, n, 2);
}
return SmallPrimes.trialDivision(n);
}
}

174
src/test/java/org/apache/commons/math4/primes/PrimesTest.java
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.math4.primes;
import java.util.HashSet;
import java.util.List;
import org.apache.commons.math4.exception.MathIllegalArgumentException;
import org.apache.commons.math4.exception.util.LocalizedFormats;
import org.apache.commons.math4.primes.Primes;
import org.apache.commons.math4.primes.SmallPrimes;
import org.junit.Assert;
import org.junit.Test;
public class PrimesTest {
public static final int[] PRIMES = {//primes here have been verified one by one using Dario Alejandro Alpern's tool, see http://www.alpertron.com.ar/ECM.HTM
2,3,5,7,11,13,17,19,23,29,31,43,47,53,71,73,79,89,97,
107,137,151,157,271,293,331,409,607,617,683,829,
1049,1103,1229,1657,
2039,2053,//around first boundary in miller-rabin
2251,2389,2473,2699,3271,3389,3449,5653,6449,6869,9067,9091,
11251,12433,12959,22961,41047,46337,65413,80803,91577,92693,
118423,656519,795659,
1373639,1373677,//around second boundary in miller-rabin
588977,952381,
1013041,1205999,2814001,
22605091,
25325981,25326023,//around third boundary in miller-rabin
100000007,715827881,
2147483647//Integer.MAX_VALUE
};
public static final int[] NOT_PRIMES = {//composite chosen at random + particular values used in algorithms such as boundaries for millerRabin
4,6,8,9,10,12,14,15,16,18,20,21,22,24,25,
275,
2037,2041,2045,2046,2047,2048,2049,2051,2055,//around first boundary in miller-rabin
9095,
463465,
1373637,1373641,1373651,1373652,1373653,1373654,1373655,1373673,1373675,1373679,//around second boundary in miller-rabin
25325979,25325983,25325993,25325997,25325999,25326001,25326003,25326007,25326009,25326011,25326021,25326025,//around third boundary in miller-rabin
100000005,
1073741341,1073741823,2147473649,2147483641,2147483643,2147483645,2147483646};
public static final int[] BELOW_2 = {
Integer.MIN_VALUE,-1,0,1};
void assertPrimeFactorsException(int n, Throwable expected) {
try {
Primes.primeFactors(n);
Assert.fail("Exception not thrown");
} catch (Throwable e) {
Assert.assertEquals(expected.getClass(), e.getClass());
if (expected.getMessage() != null) {
Assert.assertEquals(expected.getMessage(), e.getMessage());
}
}
}
void assertNextPrimeException(int n, Throwable expected){
try {
Primes.nextPrime(n);
Assert.fail("Exception not thrown");
} catch(Throwable e) {
Assert.assertEquals(expected.getClass(), e.getClass());
if (expected.getMessage() != null) {
Assert.assertEquals(expected.getMessage(), e.getMessage());
}
}
}
@Test
public void testNextPrime() {
Assert.assertEquals(2, Primes.nextPrime(0));
Assert.assertEquals(2, Primes.nextPrime(1));
Assert.assertEquals(2, Primes.nextPrime(2));
Assert.assertEquals(3, Primes.nextPrime(3));
Assert.assertEquals(5, Primes.nextPrime(4));
Assert.assertEquals(5, Primes.nextPrime(5));
for (int i = 0; i < SmallPrimes.PRIMES.length - 1; i++) {
for (int j = SmallPrimes.PRIMES[i] + 1; j <= SmallPrimes.PRIMES[i + 1]; j++) {
Assert.assertEquals(SmallPrimes.PRIMES[i+1], Primes.nextPrime(j));
}
}
Assert.assertEquals(25325981, Primes.nextPrime(25325981));
for (int i = 25325981 + 1; i <= 25326023; i++) {
Assert.assertEquals(25326023, Primes.nextPrime(i));
}
Assert.assertEquals(Integer.MAX_VALUE, Primes.nextPrime(Integer.MAX_VALUE - 10));
Assert.assertEquals(Integer.MAX_VALUE, Primes.nextPrime(Integer.MAX_VALUE - 1));
Assert.assertEquals(Integer.MAX_VALUE, Primes.nextPrime(Integer.MAX_VALUE));
assertNextPrimeException(Integer.MIN_VALUE, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,Integer.MIN_VALUE,0));
assertNextPrimeException(-1, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,-1,0));
assertNextPrimeException(-13, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,-13,0));
}
@Test
public void testIsPrime() throws Exception {
for (int i : BELOW_2) {
Assert.assertFalse(Primes.isPrime(i));
}
for (int i:NOT_PRIMES) {
Assert.assertFalse(Primes.isPrime(i));
}
for (int i:PRIMES) {
Assert.assertTrue(Primes.isPrime(i));
}
}
static int sum(List<Integer> numbers){
int out = 0;
for (int i:numbers) {
out += i;
}
return out;
}
static int product(List<Integer> numbers) {
int out = 1;
for (int i : numbers) {
out *= i;
}
return out;
}
static final HashSet<Integer> PRIMES_SET = new HashSet<>();
static {
for (int p : PRIMES) {
PRIMES_SET.add(p);
}
}
static void checkPrimeFactors(List<Integer> factors){
for (int p : factors) {
if (!PRIMES_SET.contains(p)) {
Assert.fail("Not found in primes list: " + p);
}
}
}
@Test
public void testPrimeFactors() throws Exception {
for (int i : BELOW_2) {
assertPrimeFactorsException(i, new MathIllegalArgumentException(LocalizedFormats.NUMBER_TOO_SMALL,i,2));
}
for (int i : NOT_PRIMES) {
List<Integer> factors = Primes.primeFactors(i);
checkPrimeFactors(factors);
int prod = product(factors);
Assert.assertEquals(i, prod);
}
for (int i : PRIMES) {
List<Integer> factors = Primes.primeFactors(i);
Assert.assertEquals(i, (int)factors.get(0));
Assert.assertEquals(1, factors.size());
}
}
}