boost/random/additive_combine.hpp
/* 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 52492 2009-04-19 14:55:57Z steven_watanabe $
*
* 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/detail/config.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.seed(seed1);
_mlcg2.seed(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_RANDOM_NO_STREAM_OPERATORS
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