import java.io.*; import java.util.*; /** * Mersenne Twister and MersenneTwisterFast: *
* MersenneTwisterFast is a drop-in subclass replacement * for java.util.Random. It is properly synchronized and * can be used in a multithreaded environment. * *
MersenneTwisterFast is not a subclass of java.util.Random. It has * the same public methods as Random does, however, and it is * algorithmically identical to MersenneTwister. MersenneTwisterFast * has hard-code inlined all of its methods directly, and made all of them * final (well, the ones of consequence anyway). Further, these * methods are not synchronized, so the same MersenneTwisterFast * instance cannot be shared by multiple threads. But all this helps * MersenneTwisterFast achieve over twice the speed of MersenneTwister. * *
About the Mersenne Twister. * This is a Java version of the C-program for MT19937: Integer version. * next(32) generates one pseudorandom unsigned integer (32bit) * which is uniformly distributed among 0 to 2^32-1 for each * call. next(int bits) >>>'s by (32-bits) to get a value ranging * between 0 and 2^bits-1 long inclusive; hope that's correct. * setSeed(seed) set initial values to the working area * of 624 words. For setSeed(seed), seed is any 32-bit integer * except for 0. * *
Orignally Coded by Takuji Nishimura, considering the suggestions by * Topher Cooper and Marc Rieffel in July-Aug. 1997. * More information can be found * * here. *
* Translated to Java by Michael Lecuyer January 30, 1999 * Copyright (C) 1999 Michael Lecuyer *
* This library is free software; you can redistribute it and or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 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 Library General Public License for more details. * You should have received a copy of the GNU Library General * Public License along with this library; if not, write to the * Free Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA * 02111-1307 USA *
* Makoto Matsumoto and Takuji Nishimura, the original authors * ask "When you use this, send an email to: matumoto@math.keio.ac.jp * with an appropriate reference to your work" You might also point * out this was a translation. *
* Reference. * M. Matsumoto and T. Nishimura, * "Mersenne Twister: A 623-Dimensionally Equidistributed Uniform * Pseudo-Random Number Generator", * ACM Transactions on Modeling and Computer Simulation, * Vol. 8, No. 1, January 1998, pp 3--30. * *
About this version. This is a modification of the * original * code made to conform to proper java.util.Random format by * Sean Luke, * August 7, 1999. * *
Bug Fixes. This implementation implements the bug fixes made * in Java 1.2's version of Random, which means it can be used with * earlier versions of Java. See * * the JDK 1.2 java.util.Random documentation for further documentation * on the random-number generation contracts made. Additionally, there's * an undocumented bug in the JDK java.util.Random.nextBytes() method, * which this code fixes. * *
Important Note. Just like java.util.Random, this
* generator accepts a long seed but doesn't use all of it. java.util.Random
* uses 48 bits. The Mersenne Twister instead uses 32 bits (int size).
* So it's best if your seed does not exceed the int range.
*/
public class MersenneTwisterFast implements Serializable
{
// Period parameters
private static final int N = 624;
private static final int M = 397;
private static final int MATRIX_A = 0x9908b0df; // private static final * constant vector a
private static final int UPPER_MASK = 0x80000000; // most significant w-r bits
private static final int LOWER_MASK = 0x7fffffff; // least significant r bits
// Tempering parameters
private static final int TEMPERING_MASK_B = 0x9d2c5680;
private static final int TEMPERING_MASK_C = 0xefc60000;
// #define TEMPERING_SHIFT_U(y) (y >>> 11)
// #define TEMPERING_SHIFT_S(y) (y << 7)
// #define TEMPERING_SHIFT_T(y) (y << 15)
// #define TEMPERING_SHIFT_L(y) (y >>> 18)
private int mt[]; // the array for the state vector
private int mti; // mti==N+1 means mt[N] is not initialized
private int mag01[];
// a good initial seed (of int size, though stored in a long)
private static final long GOOD_SEED = 4357;
private double nextNextGaussian;
private boolean haveNextNextGaussian;
/**
* Constructor using the default seed.
*/
public MersenneTwisterFast()
{
setSeed(GOOD_SEED);
}
/**
* Constructor using a given seed. Though you pass this seed in
* as a long, it's best to make sure it's actually an integer.
*
* @param seed generator starting number, often the time of day.
*/
public MersenneTwisterFast(long seed)
{
setSeed(seed);
}
/**
* Initalize the pseudo random number generator.
* The Mersenne Twister only uses an integer for its seed;
* It's best that you don't pass in a long that's bigger
* than an int.
*
* @param seed from constructor
*
*/
public final void setSeed(long seed)
{
haveNextNextGaussian = false;
mt = new int[N];
// setting initial seeds to mt[N] using
// the generator Line 25 of Table 1 in
// [KNUTH 1981, The Art of Computer Programming
// Vol. 2 (2nd Ed.), pp102]
// the 0xffffffff is commented out because in Java
// ints are always 32 bits; hence i & 0xffffffff == i
mt[0]= ((int)seed); // & 0xffffffff;
for (mti = 1; mti < N; mti++)
mt[mti] = (69069 * mt[mti-1]); //& 0xffffffff;
// mag01[x] = x * MATRIX_A for x=0,1
mag01 = new int[2];
mag01[0] = 0x0;
mag01[1] = MATRIX_A;
}
public final int nextInt()
{
int y;
if (mti >= N) // generate N words at one time
{
int kk;
for (kk = 0; kk < N - M; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+M] ^ (y >>> 1) ^ mag01[y & 0x1];
}
for (; kk < N-1; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+(M-N)] ^ (y >>> 1) ^ mag01[y & 0x1];
}
y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
mt[N-1] = mt[M-1] ^ (y >>> 1) ^ mag01[y & 0x1];
mti = 0;
}
y = mt[mti++];
y ^= y >>> 11; // TEMPERING_SHIFT_U(y)
y ^= (y << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(y)
y ^= (y << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(y)
y ^= (y >>> 18); // TEMPERING_SHIFT_L(y)
return y;
}
public final short nextShort()
{
int y;
if (mti >= N) // generate N words at one time
{
int kk;
for (kk = 0; kk < N - M; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+M] ^ (y >>> 1) ^ mag01[y & 0x1];
}
for (; kk < N-1; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+(M-N)] ^ (y >>> 1) ^ mag01[y & 0x1];
}
y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
mt[N-1] = mt[M-1] ^ (y >>> 1) ^ mag01[y & 0x1];
mti = 0;
}
y = mt[mti++];
y ^= y >>> 11; // TEMPERING_SHIFT_U(y)
y ^= (y << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(y)
y ^= (y << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(y)
y ^= (y >>> 18); // TEMPERING_SHIFT_L(y)
return (short)(y >>> 16);
}
public final char nextChar()
{
int y;
if (mti >= N) // generate N words at one time
{
int kk;
for (kk = 0; kk < N - M; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+M] ^ (y >>> 1) ^ mag01[y & 0x1];
}
for (; kk < N-1; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+(M-N)] ^ (y >>> 1) ^ mag01[y & 0x1];
}
y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
mt[N-1] = mt[M-1] ^ (y >>> 1) ^ mag01[y & 0x1];
mti = 0;
}
y = mt[mti++];
y ^= y >>> 11; // TEMPERING_SHIFT_U(y)
y ^= (y << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(y)
y ^= (y << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(y)
y ^= (y >>> 18); // TEMPERING_SHIFT_L(y)
return (char)(y >>> 16);
}
public final boolean nextBoolean()
{
int y;
if (mti >= N) // generate N words at one time
{
int kk;
for (kk = 0; kk < N - M; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+M] ^ (y >>> 1) ^ mag01[y & 0x1];
}
for (; kk < N-1; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+(M-N)] ^ (y >>> 1) ^ mag01[y & 0x1];
}
y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
mt[N-1] = mt[M-1] ^ (y >>> 1) ^ mag01[y & 0x1];
mti = 0;
}
y = mt[mti++];
y ^= y >>> 11; // TEMPERING_SHIFT_U(y)
y ^= (y << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(y)
y ^= (y << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(y)
y ^= (y >>> 18); // TEMPERING_SHIFT_L(y)
return (boolean)((y >>> 31) != 0);
}
public final byte nextByte()
{
int y;
if (mti >= N) // generate N words at one time
{
int kk;
for (kk = 0; kk < N - M; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+M] ^ (y >>> 1) ^ mag01[y & 0x1];
}
for (; kk < N-1; kk++)
{
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk+(M-N)] ^ (y >>> 1) ^ mag01[y & 0x1];
}
y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
mt[N-1] = mt[M-1] ^ (y >>> 1) ^ mag01[y & 0x1];
mti = 0;
}
y = mt[mti++];
y ^= y >>> 11; // TEMPERING_SHIFT_U(y)
y ^= (y << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(y)
y ^= (y << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(y)
y ^= (y >>> 18); // TEMPERING_SHIFT_L(y)
return (byte)(y >>> 24);
}
public final void nextBytes(byte[] bytes)
{
int y;
for (int x=0;x