/src/contrib/boost/random/additive_combine.hpp
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- /* 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 60755 2010-03-22 00:45:06Z 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 {
- /**
- * An instantiation of class template \additive_combine model a
- * \pseudo_random_number_generator. It combines two multiplicative
- * \linear_congruential number generators, i.e. those with @c c = 0.
- * It is described in
- *
- * @blockquote
- * "Efficient and Portable Combined Random Number Generators", Pierre L'Ecuyer,
- * Communications of the ACM, Vol. 31, No. 6, June 1988, pp. 742-749, 774
- * @endblockquote
- *
- * The template parameters MLCG1 and MLCG2 shall denote two different
- * \linear_congruential number generators, each with c = 0. Each invocation
- * returns a random number X(n) := (MLCG1(n) - MLCG2(n)) mod (m1 - 1), where
- * m1 denotes the modulus of MLCG1.
- *
- * The template parameter @c val is the validation value checked by validation.
- */
- 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
- /**
- * Returns: The smallest value that the generator can produce
- */
- result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 1; }
- /**
- * Returns: The largest value that the generator can produce
- */
- result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_mlcg1.max)()-1; }
- /**
- * Constructs an \additive_combine generator using the
- * default constructors of the two base generators.
- */
- additive_combine() : _mlcg1(), _mlcg2() { }
- /**
- * Constructs an \additive_combine generator, using aseed as
- * the constructor argument for both base generators.
- */
- explicit additive_combine(result_type aseed)
- : _mlcg1(aseed), _mlcg2(aseed) { }
- /**
- * Constructs an \additive_combine generator, using
- * @c seed1 and @c seed2 as the constructor argument to
- * the first and second base generators, respectively.
- */
- additive_combine(typename MLCG1::result_type seed1,
- typename MLCG2::result_type seed2)
- : _mlcg1(seed1), _mlcg2(seed2) { }
- /**
- * Contructs an \additive_combine generator with
- * values from the range defined by the input iterators first
- * and last. first will be modified to point to the element
- * after the last one used.
- *
- * Throws: @c std::invalid_argument if the input range is too small.
- *
- * Exception Safety: Basic
- */
- template<class It> additive_combine(It& first, It last)
- : _mlcg1(first, last), _mlcg2(first, last) { }
- /**
- * Seeds an \additive_combine generator using the default
- * seeds of the two base generators.
- */
- void seed()
- {
- _mlcg1.seed();
- _mlcg2.seed();
- }
- /**
- * Seeds an \additive_combine generator, using @c aseed as the
- * seed for both base generators.
- */
- void seed(result_type aseed)
- {
- _mlcg1.seed(aseed);
- _mlcg2.seed(aseed);
- }
- /**
- * Seeds an \additive_combine generator, using @c seed1 and @c seed2 as
- * the seeds to the first and second base generators, respectively.
- */
- void seed(typename MLCG1::result_type seed1,
- typename MLCG2::result_type seed2)
- {
- _mlcg1.seed(seed1);
- _mlcg2.seed(seed2);
- }
- /**
- * Seeds an \additive_combine generator with
- * values from the range defined by the input iterators first
- * and last. first will be modified to point to the element
- * after the last one used.
- *
- * Throws: @c std::invalid_argument if the input range is too small.
- *
- * Exception Safety: Basic
- */
- template<class It> void seed(It& first, It last)
- {
- _mlcg1.seed(first, last);
- _mlcg2.seed(first, last);
- }
- /**
- * Returns: the next value of the generator
- */
- 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
- /**
- * Writes the state of an \additive_combine generator to a @c
- * std::ostream. The textual representation of an \additive_combine
- * generator is the textual representation of the first base
- * generator followed by the textual representation of the
- * second base generator.
- */
- 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; }
- /**
- * Reads the state of an \additive_combine generator from a
- * @c std::istream.
- */
- 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
- /**
- * Returns: true iff the two \additive_combine generators will
- * produce the same sequence of values.
- */
- friend bool operator==(const additive_combine& x, const additive_combine& y)
- { return x._mlcg1 == y._mlcg1 && x._mlcg2 == y._mlcg2; }
- /**
- * Returns: true iff the two \additive_combine generators will
- * produce different sequences of values.
- */
- 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
- /**
- * The specialization \ecuyer1988 was suggested in
- *
- * @blockquote
- * "Efficient and Portable Combined Random Number Generators", Pierre L'Ecuyer,
- * Communications of the ACM, Vol. 31, No. 6, June 1988, pp. 742-749, 774
- * @endblockquote
- */
- 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