williamr@2: /* boost random/additive_combine.hpp header file
williamr@2:  *
williamr@2:  * Copyright Jens Maurer 2000-2001
williamr@2:  * Distributed under the Boost Software License, Version 1.0. (See
williamr@2:  * accompanying file LICENSE_1_0.txt or copy at
williamr@2:  * http://www.boost.org/LICENSE_1_0.txt)
williamr@2:  *
williamr@2:  * See http://www.boost.org for most recent version including documentation.
williamr@2:  *
williamr@2:  * $Id: additive_combine.hpp,v 1.11 2005/05/21 15:57:00 dgregor Exp $
williamr@2:  *
williamr@2:  * Revision history
williamr@2:  *  2001-02-18  moved to individual header files
williamr@2:  */
williamr@2: 
williamr@2: #ifndef BOOST_RANDOM_ADDITIVE_COMBINE_HPP
williamr@2: #define BOOST_RANDOM_ADDITIVE_COMBINE_HPP
williamr@2: 
williamr@2: #include <iostream>
williamr@2: #include <algorithm> // for std::min and std::max
williamr@2: #include <boost/config.hpp>
williamr@2: #include <boost/cstdint.hpp>
williamr@2: #include <boost/random/linear_congruential.hpp>
williamr@2: 
williamr@2: namespace boost {
williamr@2: namespace random {
williamr@2: 
williamr@2: // L'Ecuyer 1988
williamr@2: template<class MLCG1, class MLCG2,
williamr@2: #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS
williamr@2:   typename MLCG1::result_type 
williamr@2: #else
williamr@2:   int32_t
williamr@2: #endif
williamr@2:   val>
williamr@2: class additive_combine
williamr@2: {
williamr@2: public:
williamr@2:   typedef MLCG1 first_base;
williamr@2:   typedef MLCG2 second_base;
williamr@2:   typedef typename MLCG1::result_type result_type;
williamr@2: #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
williamr@2:   static const bool has_fixed_range = true;
williamr@2:   static const result_type min_value = 1;
williamr@2:   static const result_type max_value = MLCG1::max_value-1;
williamr@2: #else
williamr@2:   enum { has_fixed_range = false };
williamr@2: #endif
williamr@2:   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 1; }
williamr@2:   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_mlcg1.max)()-1; }
williamr@2: 
williamr@2:   additive_combine() : _mlcg1(), _mlcg2() { }
williamr@2:   additive_combine(typename MLCG1::result_type seed1, 
williamr@2:                    typename MLCG2::result_type seed2)
williamr@2:     : _mlcg1(seed1), _mlcg2(seed2) { }
williamr@2:   template<class It> additive_combine(It& first, It last)
williamr@2:     : _mlcg1(first, last), _mlcg2(first, last) { }
williamr@2: 
williamr@2:   void seed()
williamr@2:   {
williamr@2:     _mlcg1.seed();
williamr@2:     _mlcg2.seed();
williamr@2:   }
williamr@2: 
williamr@2:   void seed(typename MLCG1::result_type seed1,
williamr@2:             typename MLCG2::result_type seed2)
williamr@2:   {
williamr@2:     _mlcg1(seed1);
williamr@2:     _mlcg2(seed2);
williamr@2:   }
williamr@2: 
williamr@2:   template<class It> void seed(It& first, It last)
williamr@2:   {
williamr@2:     _mlcg1.seed(first, last);
williamr@2:     _mlcg2.seed(first, last);
williamr@2:   }
williamr@2: 
williamr@2:   result_type operator()() {
williamr@2:     result_type z = _mlcg1() - _mlcg2();
williamr@2:     if(z < 1)
williamr@2:       z += MLCG1::modulus-1;
williamr@2:     return z;
williamr@2:   }
williamr@2:   static bool validation(result_type x) { return val == x; }
williamr@2: 
williamr@2: #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE
williamr@2: 
williamr@2: #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
williamr@2:   template<class CharT, class Traits>
williamr@2:   friend std::basic_ostream<CharT,Traits>&
williamr@2:   operator<<(std::basic_ostream<CharT,Traits>& os, const additive_combine& r)
williamr@2:   { os << r._mlcg1 << " " << r._mlcg2; return os; }
williamr@2: 
williamr@2:   template<class CharT, class Traits>
williamr@2:   friend std::basic_istream<CharT,Traits>&
williamr@2:   operator>>(std::basic_istream<CharT,Traits>& is, additive_combine& r)
williamr@2:   { is >> r._mlcg1 >> std::ws >> r._mlcg2; return is; }
williamr@2: #endif
williamr@2: 
williamr@2:   friend bool operator==(const additive_combine& x, const additive_combine& y)
williamr@2:   { return x._mlcg1 == y._mlcg1 && x._mlcg2 == y._mlcg2; }
williamr@2:   friend bool operator!=(const additive_combine& x, const additive_combine& y)
williamr@2:   { return !(x == y); }
williamr@2: #else
williamr@2:   // Use a member function; Streamable concept not supported.
williamr@2:   bool operator==(const additive_combine& rhs) const
williamr@2:   { return _mlcg1 == rhs._mlcg1 && _mlcg2 == rhs._mlcg2; }
williamr@2:   bool operator!=(const additive_combine& rhs) const
williamr@2:   { return !(*this == rhs); }
williamr@2: #endif
williamr@2: private:
williamr@2:   MLCG1 _mlcg1;
williamr@2:   MLCG2 _mlcg2;
williamr@2: };
williamr@2: 
williamr@2: } // namespace random
williamr@2: 
williamr@2: typedef random::additive_combine<
williamr@2:     random::linear_congruential<int32_t, 40014, 0, 2147483563, 0>,
williamr@2:     random::linear_congruential<int32_t, 40692, 0, 2147483399, 0>,
williamr@2:   2060321752> ecuyer1988;
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_RANDOM_ADDITIVE_COMBINE_HPP