NAME

Math::Random::MT - The Mersenne Twister PRNG

SYNOPSIS

## Object-oriented interface:
use Math::Random::MT;
$gen = Math::Random::MT->new()        # or...
$gen = Math::Random::MT->new($seed);  # or...
$gen = Math::Random::MT->new(@seeds);
$seed = $gen->get_seed();             # seed used to generate the random numbers
$rand = $gen->rand(42);               # random number in the interval [0, 42)
$dice = int($gen->rand(6)+1);         # random integer between 1 and 6
$coin = $gen->rand() < 0.5 ?          # flip a coin
  "heads" : "tails"
$int = $gen->irand();                 # random integer in [0, 2^32-1]

## Function-oriented interface:
use Math::Random::MT qw(srand rand irand);
# now use srand() and rand() as you usually do in Perl

DESCRIPTION

The Mersenne Twister is a pseudorandom number generator developed by Makoto Matsumoto and Takuji Nishimura. It is described in their paper at <URL:http://www.math.keio.ac.jp/~nisimura/random/doc/mt.ps>. This algorithm has a very uniform distribution and is good for modelling purposes but do not use it for cryptography.

This module implements two interfaces:

Object-oriented interface

new()

Creates a new generator that is automatically seeded based on gettimeofday.

new($seed)

Creates a new generator seeded with an unsigned 32-bit integer.

new(@seeds)

Creates a new generator seeded with an array of (up to 624) unsigned 32-bit integers.

set_seed()

Seeds the generator and returns the seed used. It takes the same arguments as new().

get_seed()

Retrieves the value of the seed used.

rand($num)

Behaves exactly like Perl's builtin rand(), returning a number uniformly distributed in [0, $num) ($num defaults to 1).

irand()

Returns a 32-bit integer, i.e. an integer uniformly distributed in [0, 2^32-1].

Function-oriented interface

srand($seed)

Behaves just like Perl's builtin srand(). As in Perl >= 5.14, the seed is returned. If you use this interface, it is strongly recommended that you call srand() explicitly, rather than relying on rand() to call it the first time it is used.

rand($num)

Behaves exactly like Perl's builtin rand(), returning a number uniformly distributed in [0, $num) ($num defaults to 1).

irand()

Returns a 32-bit integer, i.e. an integer uniformly distributed in [0, 2^32-1].

SEE ALSO

<URL:http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html>

Data::Entropy

ACKNOWLEDGEMENTS

Sean M. Burke

For giving me the idea to write this module.

Philip Newton

For several useful patches.

Florent Angly

For implementing seed generation and retrieval.

AUTHOR

Abhijit Menon-Sen <ams@toroid.org>

Copyright 2001 Abhijit Menon-Sen. All rights reserved.

Based on the C implementation of MT19937 Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura

This software is distributed under a (three-clause) BSD-style license. See the LICENSE file in the distribution for details.