test.it.unimi.dsi.util.XoRoShiRo128PlusRandomGeneratorTest Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of dsiutils Show documentation

The DSI utilities are a mish mash of classes accumulated during the last ten years in projects developed at the DSI (Dipartimento di Scienze dell'Informazione, i.e., Information Sciences Department), now DI (Dipartimento di Informatica, i.e., Informatics Department), of the Universita` degli Studi di Milano.

There is a newer version: 2.7.3

Show newest version

package it.unimi.dsi.util;

/*		 
 * DSI utilities
 *
 * Copyright (C) 2014-2016 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 .
 *
 */


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

import org.junit.Test;


public class XoRoShiRo128PlusRandomGeneratorTest {
	private final static long seeds[] = { 0, 1, 1024, 0x5555555555555555L };

	@Test
	public void testNextFloat() {
		for ( long seed : seeds ) {
			XoRoShiRo128PlusRandomGenerator xorShift = new XoRoShiRo128PlusRandomGenerator( seed );
			double avg = 0;
			for ( int i = 1000000; i-- != 0; ) {
				float d = xorShift.nextFloat();
				assertTrue( Float.toString( d ), d < 1 );
				assertTrue( Float.toString( d ), d >= 0 );
				avg += d;
			}

			assertEquals( 500000, avg, 1000 );
		}
	}

	@Test
	public void testNextDouble() {
		for ( long seed : seeds ) {
			XoRoShiRo128PlusRandomGenerator xorShift = new XoRoShiRo128PlusRandomGenerator( seed );
			double avg = 0;
			for ( int i = 1000000; i-- != 0; ) {
				double d = xorShift.nextDouble();
				assertTrue( d < 1 );
				assertTrue( d >= 0 );
				avg += d;
			}

			assertEquals( 500000, avg, 1000 );
		}
	}

	@Test
	public void testNextInt() {
		for ( long seed : seeds ) {
			XoRoShiRo128PlusRandomGenerator xorShift = new XoRoShiRo128PlusRandomGenerator( seed );
			double avg = 0;
			for ( int i = 100000000; i-- != 0; ) {
				int d = xorShift.nextInt( 101 );
				assertTrue( d <= 100 );
				assertTrue( d >= 0 );
				avg += d;
			}

			assertEquals( 5000000000L, avg, 1000000 );
		}
	}

	@Test
	public void testNextInt2() {
		for ( long seed : seeds ) {
			XoRoShiRo128PlusRandomGenerator xorShift = new XoRoShiRo128PlusRandomGenerator( seed );
			final int[] count = new int[ 32 ];
			long change = 0;
			int prev = 0;
			for ( int i = 1000000; i-- != 0; ) {
				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, 33000 );
			for ( int b = 32; b-- != 0; ) assertEquals( 500000, count[ b ], 2000 );
		}
	}

	@Test
	public void testNextLong() {
		for ( long seed : seeds ) {
			XoRoShiRo128PlusRandomGenerator xorShift = new XoRoShiRo128PlusRandomGenerator( seed );
			final int[] count = new int[ 64 ];
			long change = 0;
			long prev = 0;
			for ( int i = 1000000; i-- != 0; ) {
				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, 7000 );
			for ( int b = 64; b-- != 0; ) assertEquals( 500000, count[ b ], 2000 );
		}
	}
	
	@Test
	public void testSameAsRandom() {
		XoRoShiRo128PlusRandom xorShiftStarRandom = new XoRoShiRo128PlusRandom( 0 );
		XoRoShiRo128PlusRandomGenerator xorShiftStar = new XoRoShiRo128PlusRandomGenerator( 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 ) );
		}
	}
}