package org.apache.lucene.util;
/*
* 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.
*/
import java.math.BigInteger;
import java.util.Arrays;
import com.carrotsearch.randomizedtesting.generators.RandomPicks;
public class TestMathUtil extends LuceneTestCase {
static long[] PRIMES = new long[] {2, 3, 5, 7, 11, 13, 17, 19, 23, 29};
static long randomLong() {
if (random().nextBoolean()) {
long l = 1;
if (random().nextBoolean()) {
l *= -1;
}
for (long i : PRIMES) {
final int m = random().nextInt(3);
for (int j = 0; j < m; ++j) {
l *= i;
}
}
return l;
} else if (random().nextBoolean()) {
return random().nextLong();
} else {
return RandomPicks.randomFrom(random(), Arrays.asList(Long.MIN_VALUE, Long.MAX_VALUE, 0L, -1L, 1L));
}
}
// slow version used for testing
static long gcd(long l1, long l2) {
final BigInteger gcd = BigInteger.valueOf(l1).gcd(BigInteger.valueOf(l2));
assert gcd.bitCount() <= 64;
return gcd.longValue();
}
public void testGCD() {
final int iters = atLeast(100);
for (int i = 0; i < iters; ++i) {
final long l1 = randomLong();
final long l2 = randomLong();
final long gcd = MathUtil.gcd(l1, l2);
final long actualGcd = gcd(l1, l2);
assertEquals(actualGcd, gcd);
if (gcd != 0) {
assertEquals(l1, (l1 / gcd) * gcd);
assertEquals(l2, (l2 / gcd) * gcd);
}
}
}
// ported test from commons-math
public void testGCD2() {
long a = 30;
long b = 50;
long c = 77;
assertEquals(0, MathUtil.gcd(0, 0));
assertEquals(b, MathUtil.gcd(0, b));
assertEquals(a, MathUtil.gcd(a, 0));
assertEquals(b, MathUtil.gcd(0, -b));
assertEquals(a, MathUtil.gcd(-a, 0));
assertEquals(10, MathUtil.gcd(a, b));
assertEquals(10, MathUtil.gcd(-a, b));
assertEquals(10, MathUtil.gcd(a, -b));
assertEquals(10, MathUtil.gcd(-a, -b));
assertEquals(1, MathUtil.gcd(a, c));
assertEquals(1, MathUtil.gcd(-a, c));
assertEquals(1, MathUtil.gcd(a, -c));
assertEquals(1, MathUtil.gcd(-a, -c));
assertEquals(3L * (1L<<45), MathUtil.gcd(3L * (1L<<50), 9L * (1L<<45)));
assertEquals(1L<<45, MathUtil.gcd(1L<<45, Long.MIN_VALUE));
assertEquals(Long.MAX_VALUE, MathUtil.gcd(Long.MAX_VALUE, 0L));
assertEquals(Long.MAX_VALUE, MathUtil.gcd(-Long.MAX_VALUE, 0L));
assertEquals(1, MathUtil.gcd(60247241209L, 153092023L));
assertEquals(Long.MIN_VALUE, MathUtil.gcd(Long.MIN_VALUE, 0));
assertEquals(Long.MIN_VALUE, MathUtil.gcd(0, Long.MIN_VALUE));
assertEquals(Long.MIN_VALUE, MathUtil.gcd(Long.MIN_VALUE, Long.MIN_VALUE));
}
}