001 /* 002 * Copyright (C) 2008-2010 by Holger Arndt 003 * 004 * This file is part of the Universal Java Matrix Package (UJMP). 005 * See the NOTICE file distributed with this work for additional 006 * information regarding copyright ownership and licensing. 007 * 008 * UJMP is free software; you can redistribute it and/or modify 009 * it under the terms of the GNU Lesser General Public License as 010 * published by the Free Software Foundation; either version 2 011 * of the License, or (at your option) any later version. 012 * 013 * UJMP is distributed in the hope that it will be useful, 014 * but WITHOUT ANY WARRANTY; without even the implied warranty of 015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 016 * GNU Lesser General Public License for more details. 017 * 018 * You should have received a copy of the GNU Lesser General Public 019 * License along with UJMP; if not, write to the 020 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, 021 * Boston, MA 02110-1301 USA 022 */ 023 024 package org.ujmp.core.util; 025 026 import java.util.Random; 027 028 /** 029 * Better than java.util.Random and almost as fast. 030 * 031 * @author arndt 032 * 033 */ 034 public class RandomMersenne extends Random { 035 private static final long serialVersionUID = 5949991470054762974L; 036 037 private long u; 038 private long v = 4101842887655102017L; 039 private long w = 1; 040 041 public RandomMersenne() { 042 this(System.nanoTime()); 043 } 044 045 public RandomMersenne(long seed) { 046 u = seed ^ v; 047 nextLong(); 048 v = u; 049 nextLong(); 050 w = v; 051 nextLong(); 052 } 053 054 public long nextLong() { 055 u = u * 2862933555777941757L + 7046029254386353087L; 056 v ^= v >>> 17; 057 v ^= v << 31; 058 v ^= v >>> 8; 059 w = 4294957665L * (w & 0xffffffff) + (w >>> 32); 060 long x = u ^ (u << 21); 061 x ^= x >>> 35; 062 x ^= x << 4; 063 long ret = (x + v) ^ w; 064 return ret; 065 } 066 067 protected int next(int bits) { 068 return (int) (nextLong() >>> (64 - bits)); 069 } 070 071 }