1 /* boost random/additive_combine.hpp header file

     2  *

     3  * Copyright Jens Maurer 2000-2001

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

     5  * accompanying file LICENSE_1_0.txt or copy at

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

     7  *

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

     9  *

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

    11  *

    12  * Revision history

    13  *  2001-02-18  moved to individual header files

    14  */

    15 

    16 #ifndef BOOST_RANDOM_ADDITIVE_COMBINE_HPP

    17 #define BOOST_RANDOM_ADDITIVE_COMBINE_HPP

    18 

    19 #include <iostream>

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

    21 #include <boost/config.hpp>

    22 #include <boost/cstdint.hpp>

    23 #include <boost/random/linear_congruential.hpp>

    24 

    25 namespace boost {

    26 namespace random {

    27 

    28 // L'Ecuyer 1988

    29 template<class MLCG1, class MLCG2,

    30 #ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS

    31   typename MLCG1::result_type 

    32 #else

    33   int32_t

    34 #endif

    35   val>

    36 class additive_combine

    37 {

    38 public:

    39   typedef MLCG1 first_base;

    40   typedef MLCG2 second_base;

    41   typedef typename MLCG1::result_type result_type;

    42 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

    43   static const bool has_fixed_range = true;

    44   static const result_type min_value = 1;

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

    46 #else

    47   enum { has_fixed_range = false };

    48 #endif

    49   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 1; }

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

    51 

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

    53   additive_combine(typename MLCG1::result_type seed1, 

    54                    typename MLCG2::result_type seed2)

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

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

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

    58 

    59   void seed()

    60   {

    61     _mlcg1.seed();

    62     _mlcg2.seed();

    63   }

    64 

    65   void seed(typename MLCG1::result_type seed1,

    66             typename MLCG2::result_type seed2)

    67   {

    68     _mlcg1(seed1);

    69     _mlcg2(seed2);

    70   }

    71 

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

    73   {

    74     _mlcg1.seed(first, last);

    75     _mlcg2.seed(first, last);

    76   }

    77 

    78   result_type operator()() {

    79     result_type z = _mlcg1() - _mlcg2();

    80     if(z < 1)

    81       z += MLCG1::modulus-1;

    82     return z;

    83   }

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

    85 

    86 #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE

    87 

    88 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS

    89   template<class CharT, class Traits>

    90   friend std::basic_ostream<CharT,Traits>&

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

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

    93 

    94   template<class CharT, class Traits>

    95   friend std::basic_istream<CharT,Traits>&

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

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

    98 #endif

    99 

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

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

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

   103   { return !(x == y); }

   104 #else

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

   106   bool operator==(const additive_combine& rhs) const

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

   108   bool operator!=(const additive_combine& rhs) const

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

   110 #endif

   111 private:

   112   MLCG1 _mlcg1;

   113   MLCG2 _mlcg2;

   114 };

   115 

   116 } // namespace random

   117 

   118 typedef random::additive_combine<

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

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

   121   2060321752> ecuyer1988;

   122 

   123 } // namespace boost

   124 

   125 #endif // BOOST_RANDOM_ADDITIVE_COMBINE_HPP