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package org.scijava.common3;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.Serializable;

/**
 * A faster version of {@link java.util.Random} functionality,
 * built on the Mersenne Twister algorithm.
 *
 * 

MersenneTwister and MersenneTwisterFast

*

* Version 17, based on version MT199937(99/10/29) of the Mersenne * Twister algorithm found at * The Mersenne Twister * Home Page, with the initialization improved using the new 2002/1/26 * initialization algorithm By Sean Luke, October 2004. *

* MersenneTwister is a drop-in subclass replacement for * java.util.Random. It is properly synchronized and can be used in a * multithreaded environment. On modern VMs such as HotSpot, it is approximately * 1/3 slower than java.util.Random. *

* 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 well over twice the speed of * MersenneTwister. java.util.Random is about 1/3 slower than * MersenneTwisterFast. *

About the Mersenne Twister

*

* This is a Java version of the C-program for MT19937: Integer version. The * MT19937 algorithm was created by Makoto Matsumoto and Takuji Nishimura, who * ask: "When you use this, send an email to: [email protected] with an * appropriate reference to your work". Indicate that this is a translation of * their algorithm into Java. *

* Reference. Makato Matsumoto and Takuji 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

*

* Changes since V16: Added nextDouble(includeZero, includeOne) and * nextFloat(includeZero, includeOne) to allow for half-open, fully-closed, and * fully-open intervals. *

* Changes Since V15: Added serialVersionUID to quiet compiler warnings * from Sun's overly verbose compilers as of JDK 1.5. *

* Changes Since V14: made strictfp, with StrictMath.log and * StrictMath.sqrt in nextGaussian instead of Math.log and Math.sqrt. This is * largely just to be safe, as it presently makes no difference in the speed, * correctness, or results of the algorithm. *

* Changes Since V13: clone() method CloneNotSupportedException removed. *

* Changes Since V12: clone() method added. *

* Changes Since V11: stateEquals(...) method added. MersenneTwisterFast * is equal to other MersenneTwisterFasts with identical state; likewise * MersenneTwister is equal to other MersenneTwister with identical state. This * isn't equals(...) because that requires a contract of immutability to compare * by value. *

* Changes Since V10: A documentation error suggested that setSeed(int[]) * required an int[] array 624 long. In fact, the array can be any non-zero * length. The new version also checks for this fact. *

* Changes Since V9: readState(stream) and writeState(stream) provided. *

* Changes Since V8: setSeed(int) was only using the first 28 bits of the * seed; it should have been 32 bits. For small-number seeds the behavior is * identical. *

* Changes Since V7: A documentation error in MersenneTwisterFast (but * not MersenneTwister) stated that nextDouble selects uniformly from the * full-open interval [0,1]. It does not. nextDouble's contract is identical * across MersenneTwisterFast, MersenneTwister, and java.util.Random, namely, * selection in the half-open interval [0,1). That is, 1.0 should not be * returned. A similar contract exists in nextFloat. *

* Changes Since V6: License has changed from LGPL to BSD. New timing * information to compare against java.util.Random. Recent versions of HotSpot * have helped Random increase in speed to the point where it is faster than * MersenneTwister but slower than MersenneTwisterFast (which should be the * case, as it's a less complex algorithm but is synchronized). *

* Changes Since V5: New empty constructor made to work the same as * java.util.Random -- namely, it seeds based on the current time in * milliseconds. *

* Changes Since V4: New initialization algorithms (see * * http://www.math.keio.ac.jp/matumoto/MT2002/emt19937ar.html). *

* The MersenneTwister code is based on standard MT19937 C/C++ code by Takuji * Nishimura, with suggestions from Topher Cooper and Marc Rieffel, July 1997. * The code was originally translated into Java by Michael Lecuyer, January * 1999, and the original code is Copyright (c) 1999 by Michael Lecuyer. *

Java notes

*

* 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. *

* 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. *

* MersenneTwister can be used reliably on JDK version 1.1.5 or above. Earlier * Java versions have serious bugs in java.util.Random; only MersenneTwisterFast * (and not MersenneTwister nor java.util.Random) should be used with them. * *

License

* Copyright (c) 2003 by Sean Luke.
* Portions copyright (c) 1993 by Michael Lecuyer.
* All rights reserved.
*

* Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: *

    *
  • Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. *
  • Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. *
  • Neither the name of the copyright owners, their employers, nor the names * of its contributors may be used to endorse or promote products derived from * this software without specific prior written permission. *
*

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNERS OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * * @author Sean Luke * @version 17 */ @SuppressWarnings("all") public strictfp class MersenneTwisterFast implements Serializable, Cloneable { // Note: this class is hard-inlined in all of its methods. This makes some // of the methods well-nigh unreadable in their complexity. In fact, the // Mersenne Twister is fairly easy code to understand: if you're trying to // get a handle on the code, I strongly suggest looking at // MersenneTwister.java first. // -- Sean // Serialization private static final long serialVersionUID = -8219700664442619525L; // locked as of Version 15 // 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; 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; /* We're overriding all internal data, to my knowledge, so this should be okay */ @Override public Object clone() { try { MersenneTwisterFast f = (MersenneTwisterFast) (super.clone()); f.mt = (int[]) (mt.clone()); f.mag01 = (int[]) (mag01.clone()); return f; } catch (CloneNotSupportedException e) { throw new InternalError(); } // should never happen } public boolean stateEquals(Object o) { if (o == this) return true; if (o == null || !(o instanceof MersenneTwisterFast)) return false; MersenneTwisterFast other = (MersenneTwisterFast) o; if (mti != other.mti) return false; for (int x = 0; x < mag01.length; x++) if (mag01[x] != other.mag01[x]) return false; for (int x = 0; x < mt.length; x++) if (mt[x] != other.mt[x]) return false; return true; } /** Reads the entire state of the MersenneTwister RNG from the stream */ public void readState(DataInputStream stream) throws IOException { int len = mt.length; for (int x = 0; x < len; x++) mt[x] = stream.readInt(); len = mag01.length; for (int x = 0; x < len; x++) mag01[x] = stream.readInt(); mti = stream.readInt(); __nextNextGaussian = stream.readDouble(); __haveNextNextGaussian = stream.readBoolean(); } /** Writes the entire state of the MersenneTwister RNG to the stream */ public void writeState(DataOutputStream stream) throws IOException { int len = mt.length; for (int x = 0; x < len; x++) stream.writeInt(mt[x]); len = mag01.length; for (int x = 0; x < len; x++) stream.writeInt(mag01[x]); stream.writeInt(mti); stream.writeDouble(__nextNextGaussian); stream.writeBoolean(__haveNextNextGaussian); } /** * Constructor using the default seed. */ public MersenneTwisterFast() { this(System.currentTimeMillis()); } /** * 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. */ public MersenneTwisterFast(final long seed) { setSeed(seed); } /** * Constructor using an array of integers as seed. Your array must have a * non-zero length. Only the first 624 integers in the array are used; if the * array is shorter than this then integers are repeatedly used in a * wrap-around fashion. */ public MersenneTwisterFast(final int[] array) { setSeed(array); } /** * Initalize the pseudo random number generator. Don't pass in a long that's * bigger than an int (Mersenne Twister only uses the first 32 bits for its * seed). */ synchronized public void setSeed(final long seed) { // Due to a bug in java.util.Random clear up to 1.2, we're // doing our own Gaussian variable. __haveNextNextGaussian = false; mt = new int[N]; mag01 = new int[2]; mag01[0] = 0x0; mag01[1] = MATRIX_A; mt[0] = (int) (seed & 0xffffffff); for (mti = 1; mti < N; mti++) { mt[mti] = (1812433253 * (mt[mti - 1] ^ (mt[mti - 1] >>> 30)) + mti); /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */ /* In the previous versions, MSBs of the seed affect */ /* only MSBs of the array mt[]. */ /* 2002/01/09 modified by Makoto Matsumoto */ mt[mti] &= 0xffffffff; /* for >32 bit machines */ } } /** * Sets the seed of the MersenneTwister using an array of integers. Your array * must have a non-zero length. Only the first 624 integers in the array are * used; if the array is shorter than this then integers are repeatedly used * in a wrap-around fashion. */ synchronized public void setSeed(final int[] array) { if (array.length == 0) throw new IllegalArgumentException( "Array length must be greater than zero"); int i, j, k; setSeed(19650218); i = 1; j = 0; k = (N > array.length ? N : array.length); for (; k != 0; k--) { mt[i] = (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >>> 30)) * 1664525)) + array[j] + j; /* non linear */ mt[i] &= 0xffffffff; /* for WORDSIZE > 32 machines */ i++; j++; if (i >= N) { mt[0] = mt[N - 1]; i = 1; } if (j >= array.length) j = 0; } for (k = N - 1; k != 0; k--) { mt[i] = (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >>> 30)) * 1566083941)) - i; /* non linear */ mt[i] &= 0xffffffff; /* for WORDSIZE > 32 machines */ i++; if (i >= N) { mt[0] = mt[N - 1]; i = 1; } } mt[0] = 0x80000000; /* MSB is 1; assuring non-zero initial array */ } public final int nextInt() { int y; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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); } /** * This generates a coin flip with a probability {@code probability} of * returning true, else returning false. {@code probability} must be between * 0.0 and 1.0, inclusive. Not as precise a random real event as * nextBoolean(double), but twice as fast. To explicitly use this, remember * you may need to cast to float first. */ public final boolean nextBoolean(final float probability) { int y; if (probability < 0.0f || probability > 1.0f) throw new IllegalArgumentException( "probability must be between 0.0 and 1.0 inclusive."); if (probability == 0.0f) return false; // fix half-open issues else if (probability == 1.0f) return true; // fix half-open issues if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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 >>> 8) / ((float) (1 << 24)) < probability; } /** * This generates a coin flip with a probability {@code probability} of * returning true, else returning false. {@code probability} must be between * 0.0 and 1.0, inclusive. */ public final boolean nextBoolean(final double probability) { int y; int z; if (probability < 0.0 || probability > 1.0) throw new IllegalArgumentException( "probability must be between 0.0 and 1.0 inclusive."); if (probability == 0.0) return false; // fix half-open issues else if (probability == 1.0) return true; // fix half-open issues if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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) if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster for (kk = 0; kk < N - M; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + M] ^ (z >>> 1) ^ mag01[z & 0x1]; } for (; kk < N - 1; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + (M - N)] ^ (z >>> 1) ^ mag01[z & 0x1]; } z = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); mt[N - 1] = mt[M - 1] ^ (z >>> 1) ^ mag01[z & 0x1]; mti = 0; } z = mt[mti++]; z ^= z >>> 11; // TEMPERING_SHIFT_U(z) z ^= (z << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(z) z ^= (z << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(z) z ^= (z >>> 18); // TEMPERING_SHIFT_L(z) /* derived from nextDouble documentation in jdk 1.2 docs, see top */ return ((((long) (y >>> 6)) << 27) + (z >>> 5)) / (double) (1L << 53) < probability; } public final byte nextByte() { int y; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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 < bytes.length; x++) { if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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) bytes[x] = (byte) (y >>> 24); } } public final long nextLong() { int y; int z; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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) if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster for (kk = 0; kk < N - M; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + M] ^ (z >>> 1) ^ mag01[z & 0x1]; } for (; kk < N - 1; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + (M - N)] ^ (z >>> 1) ^ mag01[z & 0x1]; } z = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); mt[N - 1] = mt[M - 1] ^ (z >>> 1) ^ mag01[z & 0x1]; mti = 0; } z = mt[mti++]; z ^= z >>> 11; // TEMPERING_SHIFT_U(z) z ^= (z << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(z) z ^= (z << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(z) z ^= (z >>> 18); // TEMPERING_SHIFT_L(z) return (((long) y) << 32) + (long) z; } /** * Returns a long drawn uniformly from 0 to n-1. Suffice it to say, n must be * > 0, or an IllegalArgumentException is raised. */ public final long nextLong(final long n) { if (n <= 0) throw new IllegalArgumentException("n must be positive, got: " + n); long bits, val; do { int y; int z; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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) if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster for (kk = 0; kk < N - M; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + M] ^ (z >>> 1) ^ mag01[z & 0x1]; } for (; kk < N - 1; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + (M - N)] ^ (z >>> 1) ^ mag01[z & 0x1]; } z = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); mt[N - 1] = mt[M - 1] ^ (z >>> 1) ^ mag01[z & 0x1]; mti = 0; } z = mt[mti++]; z ^= z >>> 11; // TEMPERING_SHIFT_U(z) z ^= (z << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(z) z ^= (z << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(z) z ^= (z >>> 18); // TEMPERING_SHIFT_L(z) bits = (((((long) y) << 32) + (long) z) >>> 1); val = bits % n; } while (bits - val + (n - 1) < 0); return val; } /** * Returns a random double in the half-open range from [0.0,1.0). Thus 0.0 is * a valid result but 1.0 is not. */ public final double nextDouble() { int y; int z; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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) if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster for (kk = 0; kk < N - M; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + M] ^ (z >>> 1) ^ mag01[z & 0x1]; } for (; kk < N - 1; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + (M - N)] ^ (z >>> 1) ^ mag01[z & 0x1]; } z = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); mt[N - 1] = mt[M - 1] ^ (z >>> 1) ^ mag01[z & 0x1]; mti = 0; } z = mt[mti++]; z ^= z >>> 11; // TEMPERING_SHIFT_U(z) z ^= (z << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(z) z ^= (z << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(z) z ^= (z >>> 18); // TEMPERING_SHIFT_L(z) /* derived from nextDouble documentation in jdk 1.2 docs, see top */ return ((((long) (y >>> 6)) << 27) + (z >>> 5)) / (double) (1L << 53); } /** * Returns a double in the range from 0.0 to 1.0, possibly inclusive of 0.0 * and 1.0 themselves. Thus: *

* * * * * * * * * * * * * * * * * * * * * *
Table
ExpressionInterval
nextDouble(false, false)(0.0, 1.0)
nextDouble(true, false)[0.0, 1.0)
nextDouble(false, true)(0.0, 1.0]
nextDouble(true, true)[0.0, 1.0]
*

* This version preserves all possible random values in the double range. */ public double nextDouble(boolean includeZero, boolean includeOne) { double d = 0.0; do { d = nextDouble(); // grab a value, initially from half-open [0.0, 1.0) if (includeOne && nextBoolean()) d += 1.0; // if includeOne, with 1/2 // probability, push to [1.0, // 2.0) } while ((d > 1.0) || // everything above 1.0 is always invalid (!includeZero && d == 0.0)); // if we're not including zero, 0.0 is // invalid return d; } public final double nextGaussian() { if (__haveNextNextGaussian) { __haveNextNextGaussian = false; return __nextNextGaussian; } else { double v1, v2, s; do { int y; int z; int a; int b; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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) if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster for (kk = 0; kk < N - M; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + M] ^ (z >>> 1) ^ mag01[z & 0x1]; } for (; kk < N - 1; kk++) { z = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + (M - N)] ^ (z >>> 1) ^ mag01[z & 0x1]; } z = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); mt[N - 1] = mt[M - 1] ^ (z >>> 1) ^ mag01[z & 0x1]; mti = 0; } z = mt[mti++]; z ^= z >>> 11; // TEMPERING_SHIFT_U(z) z ^= (z << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(z) z ^= (z << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(z) z ^= (z >>> 18); // TEMPERING_SHIFT_L(z) if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster for (kk = 0; kk < N - M; kk++) { a = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + M] ^ (a >>> 1) ^ mag01[a & 0x1]; } for (; kk < N - 1; kk++) { a = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + (M - N)] ^ (a >>> 1) ^ mag01[a & 0x1]; } a = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); mt[N - 1] = mt[M - 1] ^ (a >>> 1) ^ mag01[a & 0x1]; mti = 0; } a = mt[mti++]; a ^= a >>> 11; // TEMPERING_SHIFT_U(a) a ^= (a << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(a) a ^= (a << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(a) a ^= (a >>> 18); // TEMPERING_SHIFT_L(a) if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster for (kk = 0; kk < N - M; kk++) { b = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + M] ^ (b >>> 1) ^ mag01[b & 0x1]; } for (; kk < N - 1; kk++) { b = (mt[kk] & UPPER_MASK) | (mt[kk + 1] & LOWER_MASK); mt[kk] = mt[kk + (M - N)] ^ (b >>> 1) ^ mag01[b & 0x1]; } b = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK); mt[N - 1] = mt[M - 1] ^ (b >>> 1) ^ mag01[b & 0x1]; mti = 0; } b = mt[mti++]; b ^= b >>> 11; // TEMPERING_SHIFT_U(b) b ^= (b << 7) & TEMPERING_MASK_B; // TEMPERING_SHIFT_S(b) b ^= (b << 15) & TEMPERING_MASK_C; // TEMPERING_SHIFT_T(b) b ^= (b >>> 18); // TEMPERING_SHIFT_L(b) /* derived from nextDouble documentation in jdk 1.2 docs, see top */ v1 = 2 * (((((long) (y >>> 6)) << 27) + (z >>> 5)) / (double) (1L << 53)) - 1; v2 = 2 * (((((long) (a >>> 6)) << 27) + (b >>> 5)) / (double) (1L << 53)) - 1; s = v1 * v1 + v2 * v2; } while (s >= 1 || s == 0); double multiplier = StrictMath.sqrt(-2 * StrictMath.log(s) / s); __nextNextGaussian = v2 * multiplier; __haveNextNextGaussian = true; return v1 * multiplier; } } /** * Returns a random float in the half-open range from [0.0f,1.0f). Thus 0.0f * is a valid result but 1.0f is not. */ public final float nextFloat() { int y; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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 >>> 8) / ((float) (1 << 24)); } /** * Returns a float in the range from 0.0f to 1.0f, possibly inclusive of 0.0f * and 1.0f themselves. Thus: *

* * * * * * * * * * * * * * * * * * * * * *
Table
ExpressionInterval
nextFloat(false, false)(0.0f, 1.0f)
nextFloat(true, false)[0.0f, 1.0f)
nextFloat(false, true)(0.0f, 1.0f]
nextFloat(true, true)[0.0f, 1.0f]
*

* This version preserves all possible random values in the float range. */ public double nextFloat(boolean includeZero, boolean includeOne) { float d = 0.0f; do { d = nextFloat(); // grab a value, initially from half-open [0.0f, 1.0f) if (includeOne && nextBoolean()) d += 1.0f; // if includeOne, with 1/2 // probability, push to [1.0f, // 2.0f) } while ((d > 1.0f) || // everything above 1.0f is always invalid (!includeZero && d == 0.0f)); // if we're not including zero, 0.0f is // invalid return d; } /** * Returns an integer drawn uniformly from 0 to n-1. Suffice it to say, n must * be > 0, or an IllegalArgumentException is raised. */ public final int nextInt(final int n) { if (n <= 0) throw new IllegalArgumentException("n must be positive, got: " + n); if ((n & -n) == n) // i.e., n is a power of 2 { int y; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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 (int) ((n * (long) (y >>> 1)) >> 31); } int bits, val; do { int y; if (mti >= N) // generate N words at one time { int kk; final int[] mt = this.mt; // locals are slightly faster final int[] mag01 = this.mag01; // locals are slightly faster 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) bits = (y >>> 1); val = bits % n; } while (bits - val + (n - 1) < 0); return val; } }





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