| /* 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. |
| * |
| * $Id$ |
| * |
| * Revision history |
| * 2001-02-18 moved to individual header files |
| */ |
| |
| #ifndef BOOST_RANDOM_ADDITIVE_COMBINE_HPP |
| #define BOOST_RANDOM_ADDITIVE_COMBINE_HPP |
| |
| #include <istream> |
| #include <iosfwd> |
| #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/detail/operators.hpp> |
| #include <boost/random/detail/seed.hpp> |
| #include <boost/random/linear_congruential.hpp> |
| |
| namespace boost { |
| namespace random { |
| |
| /** |
| * An instantiation of class template @c additive_combine_engine models a |
| * \pseudo_random_number_generator. It combines two multiplicative |
| * \linear_congruential_engine 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_engine 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. |
| */ |
| template<class MLCG1, class MLCG2> |
| class additive_combine_engine |
| { |
| public: |
| typedef MLCG1 first_base; |
| typedef MLCG2 second_base; |
| typedef typename MLCG1::result_type result_type; |
| |
| // Required by old Boost.Random concept |
| BOOST_STATIC_CONSTANT(bool, has_fixed_range = false); |
| /** |
| * Returns the smallest value that the generator can produce |
| */ |
| static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () |
| { return 1; } |
| /** |
| * Returns the largest value that the generator can produce |
| */ |
| static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () |
| { return MLCG1::modulus-1; } |
| |
| /** |
| * Constructs an @c additive_combine_engine using the |
| * default constructors of the two base generators. |
| */ |
| additive_combine_engine() : _mlcg1(), _mlcg2() { } |
| /** |
| * Constructs an @c additive_combine_engine, using seed as |
| * the constructor argument for both base generators. |
| */ |
| BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(additive_combine_engine, |
| result_type, seed_arg) |
| { |
| _mlcg1.seed(seed_arg); |
| _mlcg2.seed(seed_arg); |
| } |
| /** |
| * Constructs an @c additive_combine_engine, using seq as |
| * the constructor argument for both base generators. |
| * |
| * @xmlwarning |
| * The semantics of this function are liable to change. |
| * A @c seed_seq is designed to generate all the seeds |
| * in one shot, but this seeds the two base engines |
| * independantly and probably ends up giving the same |
| * sequence to both. |
| * @endxmlwarning |
| */ |
| BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(additive_combine_engine, |
| SeedSeq, seq) |
| { |
| _mlcg1.seed(seq); |
| _mlcg2.seed(seq); |
| } |
| /** |
| * Constructs an @c additive_combine_engine, using |
| * @c seed1 and @c seed2 as the constructor argument to |
| * the first and second base generators, respectively. |
| */ |
| additive_combine_engine(typename MLCG1::result_type seed1, |
| typename MLCG2::result_type seed2) |
| : _mlcg1(seed1), _mlcg2(seed2) { } |
| /** |
| * Contructs an @c additive_combine_engine 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_engine(It& first, It last) |
| : _mlcg1(first, last), _mlcg2(first, last) { } |
| |
| /** |
| * Seeds an @c additive_combine_engine using the default |
| * seeds of the two base generators. |
| */ |
| void seed() |
| { |
| _mlcg1.seed(); |
| _mlcg2.seed(); |
| } |
| |
| /** |
| * Seeds an @c additive_combine_engine, using @c seed as the |
| * seed for both base generators. |
| */ |
| BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(additive_combine_engine, |
| result_type, seed_arg) |
| { |
| _mlcg1.seed(seed_arg); |
| _mlcg2.seed(seed_arg); |
| } |
| |
| /** |
| * Seeds an @c additive_combine_engine, using @c seq to |
| * seed both base generators. |
| * |
| * See the warning on the corresponding constructor. |
| */ |
| BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(additive_combine_engine, |
| SeedSeq, seq) |
| { |
| _mlcg1.seed(seq); |
| _mlcg2.seed(seq); |
| } |
| |
| /** |
| * Seeds an @c 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 @c additive_combine_engine 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 val1 = _mlcg1(); |
| result_type val2 = _mlcg2(); |
| if(val2 < val1) return val1 - val2; |
| else return val1 - val2 + MLCG1::modulus - 1; |
| } |
| |
| /** Fills a range with random values */ |
| template<class Iter> |
| void generate(Iter first, Iter last) |
| { detail::generate_from_int(*this, first, last); } |
| |
| /** Advances the state of the generator by @c z. */ |
| void discard(boost::uintmax_t z) |
| { |
| _mlcg1.discard(z); |
| _mlcg2.discard(z); |
| } |
| |
| /** |
| * Writes the state of an @c additive_combine_engine to a @c |
| * std::ostream. The textual representation of an @c |
| * additive_combine_engine is the textual representation of |
| * the first base generator followed by the textual representation |
| * of the second base generator. |
| */ |
| BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, additive_combine_engine, r) |
| { os << r._mlcg1 << ' ' << r._mlcg2; return os; } |
| |
| /** |
| * Reads the state of an @c additive_combine_engine from a |
| * @c std::istream. |
| */ |
| BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, additive_combine_engine, r) |
| { is >> r._mlcg1 >> std::ws >> r._mlcg2; return is; } |
| |
| /** |
| * Returns: true iff the two @c additive_combine_engines will |
| * produce the same sequence of values. |
| */ |
| BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(additive_combine_engine, x, y) |
| { return x._mlcg1 == y._mlcg1 && x._mlcg2 == y._mlcg2; } |
| /** |
| * Returns: true iff the two @c additive_combine_engines will |
| * produce different sequences of values. |
| */ |
| BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(additive_combine_engine) |
| |
| private: |
| MLCG1 _mlcg1; |
| MLCG2 _mlcg2; |
| }; |
| |
| #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION |
| template<class MLCG1, class MLCG2> |
| const bool additive_combine_engine<MLCG1, MLCG2>::has_fixed_range; |
| #endif |
| |
| /// \cond show_deprecated |
| |
| /** Provided for backwards compatibility. */ |
| template<class MLCG1, class MLCG2, typename MLCG1::result_type val = 0> |
| class additive_combine : public additive_combine_engine<MLCG1, MLCG2> |
| { |
| typedef additive_combine_engine<MLCG1, MLCG2> base_t; |
| public: |
| typedef typename base_t::result_type result_type; |
| additive_combine() {} |
| template<class T> |
| additive_combine(T& arg) : base_t(arg) {} |
| template<class T> |
| additive_combine(const T& arg) : base_t(arg) {} |
| template<class It> |
| additive_combine(It& first, It last) : base_t(first, last) {} |
| }; |
| |
| /// \endcond |
| |
| /** |
| * 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 additive_combine_engine< |
| linear_congruential_engine<uint32_t, 40014, 0, 2147483563>, |
| linear_congruential_engine<uint32_t, 40692, 0, 2147483399> |
| > ecuyer1988; |
| |
| } // namespace random |
| |
| using random::ecuyer1988; |
| |
| } // namespace boost |
| |
| #endif // BOOST_RANDOM_ADDITIVE_COMBINE_HPP |