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8042478: Include Mersenne primes in BigInteger primality testing

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Add testing of some of the Mersenne primes.

Reviewed-by: darcy
This commit is contained in:
Brian Burkhalter 2014-05-08 16:06:43 -07:00
parent 79cdf6ad7f
commit b84fa9d0f7
1 changed files with 39 additions and 5 deletions
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44
jdk/test/java/math/BigInteger/PrimeTest.java
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@ -31,14 +31,14 @@
*/
import java.math.BigInteger;
import java.util.BitSet;
import java.util.HashSet;
import java.util.List;
import java.util.NavigableSet;
import java.util.Set;
import java.util.SplittableRandom;
import java.util.TreeSet;
import static java.util.stream.Collectors.toCollection;
import static java.util.stream.Collectors.toList;
import java.util.stream.IntStream;
import java.util.stream.Stream;
public class PrimeTest {
@ -77,7 +77,10 @@ public class PrimeTest {
boolean nonPrimeTest = checkNonPrime(primes, certainty);
System.out.println("Non-prime test result: " + (nonPrimeTest ? "SUCCESS" : "FAILURE"));
if (!primeTest || !nonPrimeTest) {
boolean mersennePrimeTest = checkMersennePrimes(certainty);
System.out.println("Mersenne test result: " + (mersennePrimeTest ? "SUCCESS" : "FAILURE"));
if (!primeTest || !nonPrimeTest || !mersennePrimeTest) {
throw new Exception("PrimeTest FAILED!");
}
@ -133,7 +136,7 @@ public class PrimeTest {
*
* @return true if and only if the test succeeds
*/
private static boolean checkPrime(NavigableSet<BigInteger> primes,
private static boolean checkPrime(Set<BigInteger> primes,
int certainty,
boolean parallel) {
long probablePrimes = (parallel ? primes.parallelStream() : primes.stream())
@ -152,7 +155,7 @@ public class PrimeTest {
BigInteger right = t.multiply(fourToTheCMinusOne);
if (left.compareTo(right) < 0) {
System.err.println("Probable prime certainty test failed.");
System.err.println("Probable prime certainty test failed");
}
return left.compareTo(right) >= 0;
@ -193,4 +196,35 @@ public class PrimeTest {
return !failed;
}
/**
* Verifies whether a specified subset of Mersenne primes are correctly
* identified as being prime. See
* <a href="https://en.wikipedia.org/wiki/Mersenne_prime">Mersenne prime</a>
* for more information.
*
* @return true if and only if the test succeeds
*/
private static boolean checkMersennePrimes(int certainty) {
int[] MERSENNE_EXPONENTS = {
2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203,
2281, 3217, 4253, // uncomment remaining array elements to make this test run a long time
/* 4423, 9689, 9941, 11213, 19937, 21701, 23209, 44497,
86243, 110503, 132049, 216091, 756839, 859433, 1257787, 1398269,
2976221, 3021377, 6972593, 13466917, 20996011, 24036583, 25964951,
30402457, 32582657, 37156667, 42643801, 43112609, 57885161 */
};
System.out.println("Checking first "+MERSENNE_EXPONENTS.length+" Mersenne primes");
boolean result = true;
for (int n : MERSENNE_EXPONENTS) {
BigInteger mp = BigInteger.ONE.shiftLeft(n).subtract(BigInteger.ONE);
if (!mp.isProbablePrime(certainty)) {
System.err.println("Mp with p = "+n+" not classified as prime");
result = false;
}
}
return result;
}
}