test.it.unimi.dsi.util.XorShift1024StarPhiRandomGeneratorTest Maven / Gradle / Ivy

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/*
 * DSI utilities
 *
 * Copyright (C) 2013-2020 Sebastiano Vigna
 *
 *  This library is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License as published by the Free
 *  Software Foundation; either version 3 of the License, or (at your option)
 *  any later version.
 *
 *  This library 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.  See the GNU Lesser General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, see .
 *
 */

package it.unimi.dsi.util;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import org.junit.Test;

public class XorShift1024StarPhiRandomGeneratorTest {
	private final static long seeds[] = { 0, 1, 1024, 0x5555555555555555L };

	@Test
	public void testNextFloat() {
		for (final long seed : seeds) {
			final XorShift1024StarPhiRandomGenerator xorShift = new XorShift1024StarPhiRandomGenerator(seed);
			double avg = 0;
			for (int i = 1000000; i-- != 0;) {
				final float d = xorShift.nextFloat();
				assertTrue(d < 1);
				assertTrue(d >= 0);
				avg += d;
			}

			assertEquals(500000, avg, 500);
		}
	}

	@Test
	public void testNextDouble() {
		for (final long seed : seeds) {
			final XorShift1024StarPhiRandomGenerator xorShift = new XorShift1024StarPhiRandomGenerator(seed);
			double avg = 0;
			for (int i = 1000000; i-- != 0;) {
				final double d = xorShift.nextDouble();
				assertTrue(d < 1);
				assertTrue(d >= 0);
				avg += d;
			}

			assertEquals(500000, avg, 500);
		}
	}

	@Test
	public void testNextDoubleFast() {
		for (final long seed : seeds) {
			final XorShift1024StarPhiRandomGenerator xorShift = new XorShift1024StarPhiRandomGenerator(seed);
			double avg = 0;
			for (int i = 1000000; i-- != 0;) {
				final double d = xorShift.nextDoubleFast();
				assertTrue(d < 1);
				assertTrue(d >= 0);
				avg += d;
			}

			assertEquals(500000, avg, 500);
		}
	}

	@Test
	public void testNextInt() {
		for (final long seed : seeds) {
			final XorShift1024StarPhiRandomGenerator xorShift = new XorShift1024StarPhiRandomGenerator(seed);
			double avg = 0;
			for (int i = 100000000; i-- != 0;) {
				final int d = xorShift.nextInt(101);
				assertTrue(d <= 100);
				assertTrue(d >= 0);
				avg += d;
			}

			assertEquals(5000000000L, avg, 600000);
		}
	}

	@Test
	public void testNextInt2() {
		for (final long seed : seeds) {
			final XorShift1024StarPhiRandomGenerator xorShift = new XorShift1024StarPhiRandomGenerator(seed);
			final int[] count = new int[32];
			long change = 0;
			int prev = 0;
			for (int i = 1000000; i-- != 0;) {
				final int d = xorShift.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, 60000);
			for (int b = 32; b-- != 0;) assertEquals(500000, count[b], 1600);
		}
	}

	@Test
	public void testNextInt3() {
		final XorShift1024StarPhiRandomGenerator xorShiftRandom = new XorShift1024StarPhiRandomGenerator(0);
		for(int i = 0; i < 100; i++) assertTrue(xorShiftRandom.nextInt(16) < 16);
	}

	@Test
	public void testNextInt4() {
		final XorShift1024StarPhiRandomGenerator xorShift = new XorShift1024StarPhiRandomGenerator(0);
		assertEquals(0, xorShift.nextInt(1));
	}

	@Test
	public void testNextLong() {
		for (final long seed : seeds) {
			final XorShift1024StarPhiRandomGenerator xorShift = new XorShift1024StarPhiRandomGenerator(seed);
			final int[] count = new int[64];
			long change = 0;
			long prev = 0;
			for (int i = 1000000; i-- != 0;) {
				final long d = xorShift.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, 10000);
			for (int b = 64; b-- != 0;) assertEquals(500000, count[b], 1800);
		}
	}

	@Test
	public void testSameAsRandom() {
		final XorShift1024StarPhiRandom xorShiftStarRandom = new XorShift1024StarPhiRandom(0);
		final XorShift1024StarPhiRandomGenerator xorShiftStar = new XorShift1024StarPhiRandomGenerator(0);
		for(int i = 1000000; i-- != 0;) {
			assertEquals(xorShiftStar.nextLong(), xorShiftStarRandom.nextLong());
			assertEquals(0, xorShiftStar.nextDouble(), xorShiftStarRandom.nextDouble());
			assertEquals(xorShiftStar.nextInt(), xorShiftStarRandom.nextInt());
			assertEquals(xorShiftStar.nextInt(99), xorShiftStarRandom.nextInt(99));
			assertEquals(xorShiftStar.nextInt(128), xorShiftStarRandom.nextInt(128));
		}
	}

	@Test
	public void testJump() {
		final XorShift1024StarPhiRandomGenerator xorShiftRandom0 = new XorShift1024StarPhiRandomGenerator(0), xorShiftRandom1 = new XorShift1024StarPhiRandomGenerator(0);
		xorShiftRandom0.nextLong();
		xorShiftRandom0.jump();
		xorShiftRandom1.jump();
		xorShiftRandom1.nextLong();
		assertEquals(xorShiftRandom0.nextLong(), xorShiftRandom1.nextLong());
	}
}