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/*
* DSI utilities
*
* Copyright (C) 2015-2023 Sebastiano Vigna
*
* This program and the accompanying materials are made available under the
* terms of the GNU Lesser General Public License v2.1 or later,
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html,
* or the Apache Software License 2.0, which is available at
* https://www.apache.org/licenses/LICENSE-2.0.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE.
*
* SPDX-License-Identifier: LGPL-2.1-or-later OR Apache-2.0
*/
package it.unimi.dsi.util;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import org.junit.Test;
public class SplitMix64RandomTest {
private final static long seeds[] = { 0, 1, 1024, 0x5555555555555555L };
@Test
public void testNextFloat() {
for (final long seed : seeds) {
final SplitMix64Random splitMixRandom = new SplitMix64Random(seed);
double avg = 0;
for (int i = 1000000; i-- != 0;) {
final float d = splitMixRandom.nextFloat();
assertTrue(d < 1);
assertTrue(d >= 0);
avg += d;
}
assertEquals(500000, avg, 1000);
}
}
@Test
public void testNextDouble() {
for (final long seed : seeds) {
final SplitMix64Random splitMixRandom = new SplitMix64Random(seed);
double avg = 0;
for (int i = 1000000; i-- != 0;) {
final double d = splitMixRandom.nextDouble();
assertTrue(d < 1);
assertTrue(d >= 0);
avg += d;
}
assertEquals(500000, avg, 500);
}
}
@Test
public void testNextInt() {
for (final long seed : seeds) {
final SplitMix64Random splitMixRandom = new SplitMix64Random(seed);
double avg = 0;
for (int i = 100000000; i-- != 0;) {
final int d = splitMixRandom.nextInt(101);
assertTrue(d <= 100);
assertTrue(d >= 0);
avg += d;
}
assertEquals(5000000000L, avg, 1000000);
}
}
@Test
public void testNextInt2() {
for (final long seed : seeds) {
final SplitMix64Random splitMixRandom = new SplitMix64Random(seed);
final int[] count = new int[32];
long change = 0;
int prev = 0;
for (int i = 1000000; i-- != 0;) {
final int d = splitMixRandom.nextInt();
change += Long.bitCount(d ^ prev);
for (int b = 32; b-- != 0;)
if ((d & (1 << b)) != 0) count[b]++;
prev = d;
}
assertEquals(32 * 1000000L, change, 23000);
for (int b = 32; b-- != 0;) assertEquals(500000, count[b], 1500);
}
}
@Test
public void testNextLong() {
for (final long seed : seeds) {
final SplitMix64Random splitMixRandom = new SplitMix64Random(seed);
final int[] count = new int[64];
long change = 0;
long prev = 0;
for (int i = 1000000; i-- != 0;) {
final long d = splitMixRandom.nextLong();
change += Long.bitCount(d ^ prev);
for (int b = 64; b-- != 0;)
if ((d & (1L << b)) != 0) count[b]++;
prev = d;
}
assertEquals(32 * 1000000L, change, 4000);
for (int b = 64; b-- != 0;) assertEquals(500000, count[b], 1500);
}
}
}
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