mt19937rng.h

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/*
    Sheep - A Rigid Body Dynamics Engine
    Copyright (C) 2001-2004 Francois Beaune
    Contact: http://toxicengine.sourceforge.net/

    This file is part of Sheep.

    Sheep is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    Sheep 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Sheep; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

/* 
   A C-program for MT19937, with initialization improved 2002/2/10.
   Coded by Takuji Nishimura and Makoto Matsumoto.
   This is a faster version by taking Shawn Cokus's optimization,
   Matthe Bellew's simplification, Isaku Wada's real version.

   Before using, initialize the state by using init_genrand(seed) 
   or init_by_array(init_key, key_length).

   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
   All rights reserved.                          

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

     1. Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.

     2. 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.

     3. The names of its contributors may not be used to endorse or promote 
        products derived from this software without specific prior written 
        permission.

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   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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   Any feedback is very welcome.
   http://www.math.keio.ac.jp/matumoto/emt.html
   email: matumoto@math.keio.ac.jp
*/

#ifndef SHEEP_MATH_MT19937RNG_H
#define SHEEP_MATH_MT19937RNG_H

#include "common/misc/config.h"

#include <cassert>

namespace sheep {

    class MT19937RNG {
    public:
        explicit MT19937RNG(unsigned long seed = 5489UL);

        //! Seed the generator.
        void Seed(unsigned long seed);

        //! Generates and returns a random number on [0,0xffffffff] integer interval.
        unsigned long RandomInt();

        //! Generates and returns a random number on [0,1] real interval.
        double RandomReal1();

        //! Generates and returns a random number on [0,1) real interval.
        double RandomReal2();

        //! Generates and returns a random number on [a, b] integer interval, b >= a.
        long RandomInt(long a, long b);

        //! Generates and returns a random number on [a, b] real interval, b >= a.
        double RandomReal1(double a, double b);

        //! Generates and returns a random number on [a, b) real interval, b > a.
        double RandomReal2(double a, double b);

    private:
        //! Period parameters.
        enum { N = 624, M = 397 };

        unsigned long state[N]; //!< The array for the state vector.
        int left;
        unsigned long *next;

        void next_state();
    };

#include "mt19937rng.inl"

}

#endif  // !SHEEP_MATH_MT19937RNG_H

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