stream.generator

Class SFMT19937

java.lang.Object

stream.generator.SFMT19937

public class SFMT19937
extends Object

An adapation of SFMT (SIMD oriented Fast Mersenne Twister) version 1.3 by Mutsuo Saito (Hiroshima University) and Makoto Matsumoto (Hiroshima University). This adapation supports only the period 2¹⁹⁹³⁷ − 1; the original supports some longer and shorter periods.

The license (a modified BSD License) for the original C code from which this code is adapted:

 Copyright (c) 2006,2007 Mutsuo Saito, Makoto Matsumoto and Hiroshima
 University. 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 Hiroshima University 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
 OWNER 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:

Adrian King (ceroxylon at hotmail.com)

Field Summary

Fields

Modifier and Type	Field and Description
(package private) int	idx Index counter of the next int to return from next().
static int	MEXP Mersenne Exponent.
(package private) static int	MSK1 A bitmask parameter, used in the recursion to break symmetry of SIMD.
(package private) static int	MSK2 A bitmask parameter, used in the recursion to break symmetry of SIMD.
(package private) static int	MSK3 A bitmask parameter, used in the recursion to break symmetry of SIMD.
(package private) static int	MSK4 A bitmask parameter, used in the recursion to break symmetry of SIMD.
(package private) static int	N The SFMT generator has an internal state array of 128-bit integers, and N is its size.
static int	N32 N32 is the size of internal state array when regarded as an array of 32-bit integers.
(package private) static int[]	parity A parity check vector which certifies the period of 2MEXP .
(package private) static int	PARITY1 Part of a 128-bit period certification vector.
(package private) static int	PARITY2 Part of a 128-bit period certification vector.
(package private) static int	PARITY3 Part of a 128-bit period certification vector.
(package private) static int	PARITY4 Part of a 128-bit period certification vector.
(package private) static int	POS1 The pick up position of the array.
(package private) int[]	sfmt The internal state array.
(package private) static int	SL1 The parameter of shift left as four 32-bit registers.
(package private) static int	SL2 The parameter of shift left as one 128-bit register.
(package private) static int	SR1 The parameter of shift right as four 32-bit registers.
(package private) static int	SR2 The parameter of shift right as one 128-bit register.
(package private) static long	uniquifier A number mixed with the time of day to provide a unique seed to each generator of this type allocated.

Constructor Summary

Constructors

Constructor and Description
SFMT19937() Constructor that initially uses a seed based on the time of day.
SFMT19937(long seed) Constructor that initializes the internal state array by calling setSeed(long) with the specified argument.

Method Summary

Methods

Modifier and Type	Method and Description
(package private) void	doRecursion(int[] r, int rI, int[] a, int aI, int[] b, int bI, int[] c, int cI, int[] d, int dI) Applies the recursion formula.
void	fillArray(int[] array) Fills the given array with pseudorandom 32-bit integers.
void	fillArray(int[] array, int elems) Fills the given array with the specified number of pseudorandom 32-bit integers.
(package private) int	func1(int x) Used by initByArray(int...).
(package private) int	func2(int x) Used by initByArray(int...).
(package private) void	genRandAll() Fills the internal state array with pseudorandom integers.
(package private) void	genRandArray(int[] array, int size) Fills a user-specified array with pseudorandom integers.
void	initByArray(int... key) Initializes the internal state array with an array of 32-bit integers.
int	minArraySize() Returns the smallest array size allowed as an argument to fillArray(int[]).
int	next() Generates and returns the next 32-bit pseudorandom number.
(package private) void	periodCertification() Certifies the period of 2MEXP.
void	setIntSeed(int seed) Initializes the internal state array with a 32-bit seed.
void	setSeed(long seed) Initializes the internal state array with a 64-bit seed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MEXP

public static final int MEXP

Mersenne Exponent. The period of the sequence is a multiple of 2 ^MEXP − 1. If you adapt this code to support a different exponent, you must change many of the other constants here as well; consult the original C code.

See Also:

Constant Field Values

N

static final int N

The SFMT generator has an internal state array of 128-bit integers, and N is its size.

See Also:

Constant Field Values

N32

public static final int N32

N32 is the size of internal state array when regarded as an array of 32-bit integers.

See Also:

Constant Field Values

POS1

static final int POS1

The pick up position of the array.

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Constant Field Values

SL1

static final int SL1

The parameter of shift left as four 32-bit registers.

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Constant Field Values

SL2

static final int SL2

The parameter of shift left as one 128-bit register. The 128-bit integer is shifted by SL2 * 8 bits.

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Constant Field Values

SR1

static final int SR1

The parameter of shift right as four 32-bit registers.

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Constant Field Values

SR2

static final int SR2

The parameter of shift right as one 128-bit register. The 128-bit integer is shifted by SL2 * 8 bits.

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Constant Field Values

MSK1

static final int MSK1

A bitmask parameter, used in the recursion to break symmetry of SIMD.

See Also:

Constant Field Values

MSK2

static final int MSK2

A bitmask parameter, used in the recursion to break symmetry of SIMD.

See Also:

Constant Field Values

MSK3

static final int MSK3

A bitmask parameter, used in the recursion to break symmetry of SIMD.

See Also:

Constant Field Values

MSK4

static final int MSK4

A bitmask parameter, used in the recursion to break symmetry of SIMD.

See Also:

Constant Field Values

PARITY1

static final int PARITY1

Part of a 128-bit period certification vector.

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Constant Field Values

PARITY2

static final int PARITY2

Part of a 128-bit period certification vector.

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Constant Field Values

PARITY3

static final int PARITY3

Part of a 128-bit period certification vector.

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Constant Field Values

PARITY4

static final int PARITY4

Part of a 128-bit period certification vector.

See Also:

Constant Field Values

parity

static final int[] parity

A parity check vector which certifies the period of 2^MEXP .

uniquifier

static long uniquifier

A number mixed with the time of day to provide a unique seed to each generator of this type allocated.

sfmt

final int[] sfmt

The internal state array. Blocks of four consecutive ints are often treated as a single 128-bit integer that is little-endian—that is, its low-order bits are at lower indices in the array, and high-order bits at higher indices.

idx

int idx

Index counter of the next int to return from next().

Constructor Detail

SFMT19937

public SFMT19937()

Constructor that initially uses a seed based on the time of day.

SFMT19937

public SFMT19937(long seed)

Constructor that initializes the internal state array by calling setSeed(long) with the specified argument.

Parameters:

seed - initial seed for this generator.

Method Detail

doRecursion

void doRecursion(int[] r,
               int rI,
               int[] a,
               int aI,
               int[] b,
               int bI,
               int[] c,
               int cI,
               int[] d,
               int dI)

Applies the recursion formula.

Parameters:

r - output array.

rI - index in r.

a - state array.

aI - index in a.

b - state array.

bI - index in b.

c - state array.

cI - index in c.

d - state array.

dI - index in d.

genRandAll

void genRandAll()

Fills the internal state array with pseudorandom integers.

genRandArray

void genRandArray(int[] array,
                int size)

Fills a user-specified array with pseudorandom integers.

Parameters:

array - 128-bit array to be filled with pseudorandom numbers.

size - number of elements of array to fill.

Throws:

IllegalArgumentException - if size is greater than the length of array, or if size is less than N32, or is not a multiple of 4.

func1

int func1(int x)

Used by initByArray(int...).

Parameters:

x - 32-bit integer.

Returns:

32-bit integer.

func2

int func2(int x)

Used by initByArray(int...).

Parameters:

x - 32-bit integer.

Returns:

32-bit integer.

periodCertification

void periodCertification()

Certifies the period of 2^MEXP.

minArraySize

public int minArraySize()

Returns the smallest array size allowed as an argument to fillArray(int[]).

next

public int next()

Generates and returns the next 32-bit pseudorandom number.

Returns:

next number.

fillArray

public void fillArray(int[] array)

Fills the given array with pseudorandom 32-bit integers. Equivalent to fillArray(int[],int) applied to (array,array.length).

Parameters:

array - array to fill.

fillArray

public void fillArray(int[] array,
             int elems)

Fills the given array with the specified number of pseudorandom 32-bit integers. The specified number of elements must be a multiple of four.

Parameters:

array - array to fill.

elems - the number of elements of array (starting at index zero) to fill; subsequent elements are not modified.

Throws:

IllegalArgumentException - if elems is greater than the length of array, or is less than N32, or is not a multiple of 4.

setIntSeed

public void setIntSeed(int seed)

Initializes the internal state array with a 32-bit seed.

Parameters:

seed - 32-bit seed.

setSeed

public void setSeed(long seed)

Initializes the internal state array with a 64-bit seed.

Parameters:

seed - 64-bit seed.

initByArray

public void initByArray(int... key)

Initializes the internal state array with an array of 32-bit integers.

Parameters:

key - array of 32-bit integers, used as a seed.