/* boost random/additive_combine.hpp header file

  *

  * Copyright Jens Maurer 2000-2001

  * Distributed under the Boost Software License, Version 1.0. (See

  * accompanying file LICENSE_1_0.txt or copy at

  * http://www.boost.org/LICENSE_1_0.txt)

  *

  * See http://www.boost.org for most recent version including documentation.

  *

  * $Id: additive_combine.hpp,v 1.11 2005/05/21 15:57:00 dgregor Exp $

  *

  * Revision history

  *  2001-02-18  moved to individual header files

  */

 #ifndef BOOST_RANDOM_ADDITIVE_COMBINE_HPP

 #define BOOST_RANDOM_ADDITIVE_COMBINE_HPP

 #include <iostream>

 #include <algorithm> // for std::min and std::max

 #include <boost/config.hpp>

 #include <boost/cstdint.hpp>

 #include <boost/random/linear_congruential.hpp>

 namespace boost {

 namespace random {

 // L'Ecuyer 1988

 template<class MLCG1, class MLCG2,

 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS

   typename MLCG1::result_type 

 #else

   int32_t

 #endif

   val>

 class additive_combine

 {

 public:

   typedef MLCG1 first_base;

   typedef MLCG2 second_base;

   typedef typename MLCG1::result_type result_type;

 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

   static const bool has_fixed_range = true;

   static const result_type min_value = 1;

   static const result_type max_value = MLCG1::max_value-1;

 #else

   enum { has_fixed_range = false };

 #endif

   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 1; }

   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_mlcg1.max)()-1; }

   additive_combine() : _mlcg1(), _mlcg2() { }

   additive_combine(typename MLCG1::result_type seed1, 

                    typename MLCG2::result_type seed2)

     : _mlcg1(seed1), _mlcg2(seed2) { }

   template<class It> additive_combine(It& first, It last)

     : _mlcg1(first, last), _mlcg2(first, last) { }

   void seed()

   {

     _mlcg1.seed();

     _mlcg2.seed();

   }

   void seed(typename MLCG1::result_type seed1,

             typename MLCG2::result_type seed2)

   {

     _mlcg1(seed1);

     _mlcg2(seed2);

   }

   template<class It> void seed(It& first, It last)

   {

     _mlcg1.seed(first, last);

     _mlcg2.seed(first, last);

   }

   result_type operator()() {

     result_type z = _mlcg1() - _mlcg2();

     if(z < 1)

       z += MLCG1::modulus-1;

     return z;

   }

   static bool validation(result_type x) { return val == x; }

 #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE

 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS

   template<class CharT, class Traits>

   friend std::basic_ostream<CharT,Traits>&

   operator<<(std::basic_ostream<CharT,Traits>& os, const additive_combine& r)

   { os << r._mlcg1 << " " << r._mlcg2; return os; }

   template<class CharT, class Traits>

   friend std::basic_istream<CharT,Traits>&

   operator>>(std::basic_istream<CharT,Traits>& is, additive_combine& r)

   { is >> r._mlcg1 >> std::ws >> r._mlcg2; return is; }

 #endif

   friend bool operator==(const additive_combine& x, const additive_combine& y)

   { return x._mlcg1 == y._mlcg1 && x._mlcg2 == y._mlcg2; }

   friend bool operator!=(const additive_combine& x, const additive_combine& y)

   { return !(x == y); }

 #else

   // Use a member function; Streamable concept not supported.

   bool operator==(const additive_combine& rhs) const

   { return _mlcg1 == rhs._mlcg1 && _mlcg2 == rhs._mlcg2; }

   bool operator!=(const additive_combine& rhs) const

   { return !(*this == rhs); }

 #endif

 private:

   MLCG1 _mlcg1;

   MLCG2 _mlcg2;

 };

 } // namespace random

 typedef random::additive_combine<

     random::linear_congruential<int32_t, 40014, 0, 2147483563, 0>,

     random::linear_congruential<int32_t, 40692, 0, 2147483399, 0>,

   2060321752> ecuyer1988;

 } // namespace boost

 #endif // BOOST_RANDOM_ADDITIVE_COMBINE_HPP