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			467 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
|   | /* boost random/linear_congruential.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_LINEAR_CONGRUENTIAL_HPP | ||
|  | #define BOOST_RANDOM_LINEAR_CONGRUENTIAL_HPP | ||
|  | 
 | ||
|  | #include <iostream> | ||
|  | #include <stdexcept> | ||
|  | #include <boost/assert.hpp> | ||
|  | #include <boost/config.hpp> | ||
|  | #include <boost/cstdint.hpp> | ||
|  | #include <boost/limits.hpp> | ||
|  | #include <boost/static_assert.hpp> | ||
|  | #include <boost/integer/static_log2.hpp> | ||
|  | #include <boost/mpl/if.hpp> | ||
|  | #include <boost/type_traits/is_arithmetic.hpp> | ||
|  | #include <boost/random/detail/config.hpp> | ||
|  | #include <boost/random/detail/const_mod.hpp> | ||
|  | #include <boost/random/detail/seed.hpp> | ||
|  | #include <boost/random/detail/seed_impl.hpp> | ||
|  | #include <boost/detail/workaround.hpp> | ||
|  | 
 | ||
|  | #include <boost/random/detail/disable_warnings.hpp> | ||
|  | 
 | ||
|  | namespace boost { | ||
|  | namespace random { | ||
|  | 
 | ||
|  | /** | ||
|  |  * Instantiations of class template linear_congruential_engine model a | ||
|  |  * \pseudo_random_number_generator. Linear congruential pseudo-random | ||
|  |  * number generators are described in: | ||
|  |  * | ||
|  |  *  @blockquote | ||
|  |  *  "Mathematical methods in large-scale computing units", D. H. Lehmer, | ||
|  |  *  Proc. 2nd Symposium on Large-Scale Digital Calculating Machines, | ||
|  |  *  Harvard University Press, 1951, pp. 141-146 | ||
|  |  *  @endblockquote | ||
|  |  * | ||
|  |  * Let x(n) denote the sequence of numbers returned by some pseudo-random | ||
|  |  * number generator. Then for the linear congruential generator, | ||
|  |  * x(n+1) := (a * x(n) + c) mod m. Parameters for the generator are | ||
|  |  * x(0), a, c, m. The template parameter IntType shall denote an integral | ||
|  |  * type. It must be large enough to hold values a, c, and m. The template | ||
|  |  * parameters a and c must be smaller than m. | ||
|  |  * | ||
|  |  * Note: The quality of the generator crucially depends on the choice of | ||
|  |  * the parameters. User code should use one of the sensibly parameterized | ||
|  |  * generators such as minstd_rand instead. | ||
|  |  */ | ||
|  | template<class IntType, IntType a, IntType c, IntType m> | ||
|  | class linear_congruential_engine | ||
|  | { | ||
|  | public: | ||
|  |     typedef IntType result_type; | ||
|  | 
 | ||
|  |     // Required for old Boost.Random concept | ||
|  |     BOOST_STATIC_CONSTANT(bool, has_fixed_range = false); | ||
|  | 
 | ||
|  |     BOOST_STATIC_CONSTANT(IntType, multiplier = a); | ||
|  |     BOOST_STATIC_CONSTANT(IntType, increment = c); | ||
|  |     BOOST_STATIC_CONSTANT(IntType, modulus = m); | ||
|  |     BOOST_STATIC_CONSTANT(IntType, default_seed = 1); | ||
|  |      | ||
|  |     BOOST_STATIC_ASSERT(std::numeric_limits<IntType>::is_integer); | ||
|  |     BOOST_STATIC_ASSERT(m == 0 || a < m); | ||
|  |     BOOST_STATIC_ASSERT(m == 0 || c < m); | ||
|  |      | ||
|  |     /** | ||
|  |      * Constructs a @c linear_congruential_engine, using the default seed | ||
|  |      */ | ||
|  |     linear_congruential_engine() { seed(); } | ||
|  | 
 | ||
|  |     /** | ||
|  |      * Constructs a @c linear_congruential_engine, seeding it with @c x0. | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(linear_congruential_engine, | ||
|  |                                                IntType, x0) | ||
|  |     { seed(x0); } | ||
|  |      | ||
|  |     /** | ||
|  |      * Constructs a @c linear_congruential_engine, seeding it with values | ||
|  |      * produced by a call to @c seq.generate(). | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(linear_congruential_engine, | ||
|  |                                              SeedSeq, seq) | ||
|  |     { seed(seq); } | ||
|  | 
 | ||
|  |     /** | ||
|  |      * Constructs a @c linear_congruential_engine  and seeds it | ||
|  |      * with values taken from the itrator range [first, last) | ||
|  |      * and adjusts first to point to the element after the last one | ||
|  |      * used.  If there are not enough elements, throws @c std::invalid_argument. | ||
|  |      * | ||
|  |      * first and last must be input iterators. | ||
|  |      */ | ||
|  |     template<class It> | ||
|  |     linear_congruential_engine(It& first, It last) | ||
|  |     { | ||
|  |         seed(first, last); | ||
|  |     } | ||
|  | 
 | ||
|  |     // compiler-generated copy constructor and assignment operator are fine | ||
|  | 
 | ||
|  |     /** | ||
|  |      * Calls seed(default_seed) | ||
|  |      */ | ||
|  |     void seed() { seed(default_seed); } | ||
|  | 
 | ||
|  |     /** | ||
|  |      * If c mod m is zero and x0 mod m is zero, changes the current value of | ||
|  |      * the generator to 1. Otherwise, changes it to x0 mod m. If c is zero, | ||
|  |      * distinct seeds in the range [1,m) will leave the generator in distinct | ||
|  |      * states. If c is not zero, the range is [0,m). | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(linear_congruential_engine, IntType, x0) | ||
|  |     { | ||
|  |         // wrap _x if it doesn't fit in the destination | ||
|  |         if(modulus == 0) { | ||
|  |             _x = x0; | ||
|  |         } else { | ||
|  |             _x = x0 % modulus; | ||
|  |         } | ||
|  |         // handle negative seeds | ||
|  |         if(_x <= 0 && _x != 0) { | ||
|  |             _x += modulus; | ||
|  |         } | ||
|  |         // adjust to the correct range | ||
|  |         if(increment == 0 && _x == 0) { | ||
|  |             _x = 1; | ||
|  |         } | ||
|  |         BOOST_ASSERT(_x >= (min)()); | ||
|  |         BOOST_ASSERT(_x <= (max)()); | ||
|  |     } | ||
|  | 
 | ||
|  |     /** | ||
|  |      * Seeds a @c linear_congruential_engine using values from a SeedSeq. | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(linear_congruential_engine, SeedSeq, seq) | ||
|  |     { seed(detail::seed_one_int<IntType, m>(seq)); } | ||
|  | 
 | ||
|  |     /** | ||
|  |      * seeds a @c linear_congruential_engine with values taken | ||
|  |      * from the itrator range [first, last) and adjusts @c first to | ||
|  |      * point to the element after the last one used.  If there are | ||
|  |      * not enough elements, throws @c std::invalid_argument. | ||
|  |      * | ||
|  |      * @c first and @c last must be input iterators. | ||
|  |      */ | ||
|  |     template<class It> | ||
|  |     void seed(It& first, It last) | ||
|  |     { seed(detail::get_one_int<IntType, m>(first, last)); } | ||
|  | 
 | ||
|  |     /** | ||
|  |      * Returns the smallest value that the @c linear_congruential_engine | ||
|  |      * can produce. | ||
|  |      */ | ||
|  |     static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () | ||
|  |     { return c == 0 ? 1 : 0; } | ||
|  |     /** | ||
|  |      * Returns the largest value that the @c linear_congruential_engine | ||
|  |      * can produce. | ||
|  |      */ | ||
|  |     static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () | ||
|  |     { return modulus-1; } | ||
|  | 
 | ||
|  |     /** Returns the next value of the @c linear_congruential_engine. */ | ||
|  |     IntType operator()() | ||
|  |     { | ||
|  |         _x = const_mod<IntType, m>::mult_add(a, _x, c); | ||
|  |         return _x; | ||
|  |     } | ||
|  |    | ||
|  |     /** 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) | ||
|  |     { | ||
|  |         typedef const_mod<IntType, m> mod_type; | ||
|  |         IntType b_inv = mod_type::invert(a-1); | ||
|  |         IntType b_gcd = mod_type::mult(a-1, b_inv); | ||
|  |         if(b_gcd == 1) { | ||
|  |             IntType a_z = mod_type::pow(a, z); | ||
|  |             _x = mod_type::mult_add(a_z, _x,  | ||
|  |                 mod_type::mult(mod_type::mult(c, b_inv), a_z - 1)); | ||
|  |         } else { | ||
|  |             // compute (a^z - 1)*c % (b_gcd * m) / (b / b_gcd) * inv(b / b_gcd) | ||
|  |             // we're storing the intermediate result / b_gcd | ||
|  |             IntType a_zm1_over_gcd = 0; | ||
|  |             IntType a_km1_over_gcd = (a - 1) / b_gcd; | ||
|  |             boost::uintmax_t exponent = z; | ||
|  |             while(exponent != 0) { | ||
|  |                 if(exponent % 2 == 1) { | ||
|  |                     a_zm1_over_gcd = | ||
|  |                         mod_type::mult_add( | ||
|  |                             b_gcd, | ||
|  |                             mod_type::mult(a_zm1_over_gcd, a_km1_over_gcd), | ||
|  |                             mod_type::add(a_zm1_over_gcd, a_km1_over_gcd)); | ||
|  |                 } | ||
|  |                 a_km1_over_gcd = mod_type::mult_add( | ||
|  |                     b_gcd, | ||
|  |                     mod_type::mult(a_km1_over_gcd, a_km1_over_gcd), | ||
|  |                     mod_type::add(a_km1_over_gcd, a_km1_over_gcd)); | ||
|  |                 exponent /= 2; | ||
|  |             } | ||
|  |              | ||
|  |             IntType a_z = mod_type::mult_add(b_gcd, a_zm1_over_gcd, 1); | ||
|  |             IntType num = mod_type::mult(c, a_zm1_over_gcd); | ||
|  |             b_inv = mod_type::invert((a-1)/b_gcd); | ||
|  |             _x = mod_type::mult_add(a_z, _x, mod_type::mult(b_inv, num)); | ||
|  |         } | ||
|  |     } | ||
|  | 
 | ||
|  |     friend bool operator==(const linear_congruential_engine& x, | ||
|  |                            const linear_congruential_engine& y) | ||
|  |     { return x._x == y._x; } | ||
|  |     friend bool operator!=(const linear_congruential_engine& x, | ||
|  |                            const linear_congruential_engine& y) | ||
|  |     { return !(x == y); } | ||
|  |      | ||
|  | #if !defined(BOOST_RANDOM_NO_STREAM_OPERATORS) | ||
|  |     /** Writes a @c linear_congruential_engine to a @c std::ostream. */ | ||
|  |     template<class CharT, class Traits> | ||
|  |     friend std::basic_ostream<CharT,Traits>& | ||
|  |     operator<<(std::basic_ostream<CharT,Traits>& os, | ||
|  |                const linear_congruential_engine& lcg) | ||
|  |     { | ||
|  |         return os << lcg._x; | ||
|  |     } | ||
|  | 
 | ||
|  |     /** Reads a @c linear_congruential_engine from a @c std::istream. */ | ||
|  |     template<class CharT, class Traits> | ||
|  |     friend std::basic_istream<CharT,Traits>& | ||
|  |     operator>>(std::basic_istream<CharT,Traits>& is, | ||
|  |                linear_congruential_engine& lcg) | ||
|  |     { | ||
|  |         lcg.read(is); | ||
|  |         return is; | ||
|  |     } | ||
|  | #endif | ||
|  | 
 | ||
|  | private: | ||
|  | 
 | ||
|  |     /// \cond show_private | ||
|  | 
 | ||
|  |     template<class CharT, class Traits> | ||
|  |     void read(std::basic_istream<CharT, Traits>& is) { | ||
|  |         IntType x; | ||
|  |         if(is >> x) { | ||
|  |             if(x >= (min)() && x <= (max)()) { | ||
|  |                 _x = x; | ||
|  |             } else { | ||
|  |                 is.setstate(std::ios_base::failbit); | ||
|  |             } | ||
|  |         } | ||
|  |     } | ||
|  | 
 | ||
|  |     /// \endcond | ||
|  | 
 | ||
|  |     IntType _x; | ||
|  | }; | ||
|  | 
 | ||
|  | #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION | ||
|  | //  A definition is required even for integral static constants | ||
|  | template<class IntType, IntType a, IntType c, IntType m> | ||
|  | const bool linear_congruential_engine<IntType, a, c, m>::has_fixed_range; | ||
|  | template<class IntType, IntType a, IntType c, IntType m> | ||
|  | const IntType linear_congruential_engine<IntType,a,c,m>::multiplier; | ||
|  | template<class IntType, IntType a, IntType c, IntType m> | ||
|  | const IntType linear_congruential_engine<IntType,a,c,m>::increment; | ||
|  | template<class IntType, IntType a, IntType c, IntType m> | ||
|  | const IntType linear_congruential_engine<IntType,a,c,m>::modulus; | ||
|  | template<class IntType, IntType a, IntType c, IntType m> | ||
|  | const IntType linear_congruential_engine<IntType,a,c,m>::default_seed; | ||
|  | #endif | ||
|  | 
 | ||
|  | /// \cond show_deprecated | ||
|  | 
 | ||
|  | // provided for backwards compatibility | ||
|  | template<class IntType, IntType a, IntType c, IntType m, IntType val = 0> | ||
|  | class linear_congruential : public linear_congruential_engine<IntType, a, c, m> | ||
|  | { | ||
|  |     typedef linear_congruential_engine<IntType, a, c, m> base_type; | ||
|  | public: | ||
|  |     linear_congruential(IntType x0 = 1) : base_type(x0) {} | ||
|  |     template<class It> | ||
|  |     linear_congruential(It& first, It last) : base_type(first, last) {} | ||
|  | }; | ||
|  | 
 | ||
|  | /// \endcond | ||
|  | 
 | ||
|  | /** | ||
|  |  * The specialization \minstd_rand0 was originally suggested in | ||
|  |  * | ||
|  |  *  @blockquote | ||
|  |  *  A pseudo-random number generator for the System/360, P.A. Lewis, | ||
|  |  *  A.S. Goodman, J.M. Miller, IBM Systems Journal, Vol. 8, No. 2, | ||
|  |  *  1969, pp. 136-146 | ||
|  |  *  @endblockquote | ||
|  |  * | ||
|  |  * It is examined more closely together with \minstd_rand in | ||
|  |  * | ||
|  |  *  @blockquote | ||
|  |  *  "Random Number Generators: Good ones are hard to find", | ||
|  |  *  Stephen K. Park and Keith W. Miller, Communications of | ||
|  |  *  the ACM, Vol. 31, No. 10, October 1988, pp. 1192-1201  | ||
|  |  *  @endblockquote | ||
|  |  */ | ||
|  | typedef linear_congruential_engine<uint32_t, 16807, 0, 2147483647> minstd_rand0; | ||
|  | 
 | ||
|  | /** The specialization \minstd_rand was suggested in | ||
|  |  * | ||
|  |  *  @blockquote | ||
|  |  *  "Random Number Generators: Good ones are hard to find", | ||
|  |  *  Stephen K. Park and Keith W. Miller, Communications of | ||
|  |  *  the ACM, Vol. 31, No. 10, October 1988, pp. 1192-1201 | ||
|  |  *  @endblockquote | ||
|  |  */ | ||
|  | typedef linear_congruential_engine<uint32_t, 48271, 0, 2147483647> minstd_rand; | ||
|  | 
 | ||
|  | 
 | ||
|  | #if !defined(BOOST_NO_INT64_T) && !defined(BOOST_NO_INTEGRAL_INT64_T) | ||
|  | /** | ||
|  |  * Class @c rand48 models a \pseudo_random_number_generator. It uses | ||
|  |  * the linear congruential algorithm with the parameters a = 0x5DEECE66D, | ||
|  |  * c = 0xB, m = 2**48. It delivers identical results to the @c lrand48() | ||
|  |  * function available on some systems (assuming lcong48 has not been called). | ||
|  |  * | ||
|  |  * It is only available on systems where @c uint64_t is provided as an | ||
|  |  * integral type, so that for example static in-class constants and/or | ||
|  |  * enum definitions with large @c uint64_t numbers work. | ||
|  |  */ | ||
|  | class rand48  | ||
|  | { | ||
|  | public: | ||
|  |     typedef boost::uint32_t result_type; | ||
|  | 
 | ||
|  |     BOOST_STATIC_CONSTANT(bool, has_fixed_range = false); | ||
|  |     /** | ||
|  |      * Returns the smallest value that the generator can produce | ||
|  |      */ | ||
|  |     static uint32_t min BOOST_PREVENT_MACRO_SUBSTITUTION () { return 0; } | ||
|  |     /** | ||
|  |      * Returns the largest value that the generator can produce | ||
|  |      */ | ||
|  |     static uint32_t max BOOST_PREVENT_MACRO_SUBSTITUTION () | ||
|  |     { return 0x7FFFFFFF; } | ||
|  |    | ||
|  |     /** Seeds the generator with the default seed. */ | ||
|  |     rand48() : lcf(cnv(static_cast<uint32_t>(1))) {} | ||
|  |     /** | ||
|  |      * Constructs a \rand48 generator with x(0) := (x0 << 16) | 0x330e. | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(rand48, result_type, x0) | ||
|  |     { seed(x0); } | ||
|  |     /** | ||
|  |      * Seeds the generator with values produced by @c seq.generate(). | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(rand48, SeedSeq, seq) | ||
|  |     { seed(seq); } | ||
|  |     /** | ||
|  |      * Seeds the generator using values from an iterator range, | ||
|  |      * and updates first to point one past the last value consumed. | ||
|  |      */ | ||
|  |     template<class It> rand48(It& first, It last) : lcf(first, last) { } | ||
|  | 
 | ||
|  |     // compiler-generated copy ctor and assignment operator are fine | ||
|  | 
 | ||
|  |     /** Seeds the generator with the default seed. */ | ||
|  |     void seed() { seed(static_cast<uint32_t>(1)); } | ||
|  |     /** | ||
|  |      * Changes the current value x(n) of the generator to (x0 << 16) | 0x330e. | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(rand48, result_type, x0) | ||
|  |     { lcf.seed(cnv(x0)); } | ||
|  |     /** | ||
|  |      * Seeds the generator using values from an iterator range, | ||
|  |      * and updates first to point one past the last value consumed. | ||
|  |      */ | ||
|  |     template<class It> void seed(It& first, It last) { lcf.seed(first,last); } | ||
|  |     /** | ||
|  |      * Seeds the generator with values produced by @c seq.generate(). | ||
|  |      */ | ||
|  |     BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(rand48, SeedSeq, seq) | ||
|  |     { lcf.seed(seq); } | ||
|  | 
 | ||
|  |     /**  Returns the next value of the generator. */ | ||
|  |     uint32_t operator()() { return static_cast<uint32_t>(lcf() >> 17); } | ||
|  |      | ||
|  |     /** Advances the state of the generator by @c z. */ | ||
|  |     void discard(boost::uintmax_t z) { lcf.discard(z); } | ||
|  |    | ||
|  |     /** Fills a range with random values */ | ||
|  |     template<class Iter> | ||
|  |     void generate(Iter first, Iter last) | ||
|  |     { | ||
|  |         for(; first != last; ++first) { | ||
|  |             *first = (*this)(); | ||
|  |         } | ||
|  |     } | ||
|  | 
 | ||
|  | #ifndef BOOST_RANDOM_NO_STREAM_OPERATORS | ||
|  |     /**  Writes a @c rand48 to a @c std::ostream. */ | ||
|  |     template<class CharT,class Traits> | ||
|  |     friend std::basic_ostream<CharT,Traits>& | ||
|  |     operator<<(std::basic_ostream<CharT,Traits>& os, const rand48& r) | ||
|  |     { os << r.lcf; return os; } | ||
|  | 
 | ||
|  |     /** Reads a @c rand48 from a @c std::istream. */ | ||
|  |     template<class CharT,class Traits> | ||
|  |     friend std::basic_istream<CharT,Traits>& | ||
|  |     operator>>(std::basic_istream<CharT,Traits>& is, rand48& r) | ||
|  |     { is >> r.lcf; return is; } | ||
|  | #endif | ||
|  | 
 | ||
|  |     /** | ||
|  |      * Returns true if the two generators will produce identical | ||
|  |      * sequences of values. | ||
|  |      */ | ||
|  |     friend bool operator==(const rand48& x, const rand48& y) | ||
|  |     { return x.lcf == y.lcf; } | ||
|  |     /** | ||
|  |      * Returns true if the two generators will produce different | ||
|  |      * sequences of values. | ||
|  |      */ | ||
|  |     friend bool operator!=(const rand48& x, const rand48& y) | ||
|  |     { return !(x == y); } | ||
|  | private: | ||
|  |     /// \cond show_private | ||
|  |     typedef random::linear_congruential_engine<uint64_t, | ||
|  |         // xxxxULL is not portable | ||
|  |         uint64_t(0xDEECE66DUL) | (uint64_t(0x5) << 32), | ||
|  |         0xB, uint64_t(1)<<48> lcf_t; | ||
|  |     lcf_t lcf; | ||
|  | 
 | ||
|  |     static boost::uint64_t cnv(boost::uint32_t x) | ||
|  |     { return (static_cast<uint64_t>(x) << 16) | 0x330e; } | ||
|  |     /// \endcond | ||
|  | }; | ||
|  | #endif /* !BOOST_NO_INT64_T && !BOOST_NO_INTEGRAL_INT64_T */ | ||
|  | 
 | ||
|  | } // namespace random | ||
|  | 
 | ||
|  | using random::minstd_rand0; | ||
|  | using random::minstd_rand; | ||
|  | using random::rand48; | ||
|  | 
 | ||
|  | } // namespace boost | ||
|  | 
 | ||
|  | #include <boost/random/detail/enable_warnings.hpp> | ||
|  | 
 | ||
|  | #endif // BOOST_RANDOM_LINEAR_CONGRUENTIAL_HPP |