| /* 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: linear_congruential.hpp 60755 2010-03-22 00:45:06Z steven_watanabe $ |
| * |
| * 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 <cassert> |
| #include <stdexcept> |
| #include <boost/config.hpp> |
| #include <boost/limits.hpp> |
| #include <boost/static_assert.hpp> |
| #include <boost/random/detail/config.hpp> |
| #include <boost/random/detail/const_mod.hpp> |
| #include <boost/detail/workaround.hpp> |
| |
| #include <boost/random/detail/disable_warnings.hpp> |
| |
| namespace boost { |
| namespace random { |
| |
| /** |
| * Instantiations of class template linear_congruential model a |
| * \pseudo_random_number_generator. Linear congruential pseudo-random |
| * number generators are described in: |
| * |
| * "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 |
| * |
| * 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, IntType val> |
| class linear_congruential |
| { |
| public: |
| typedef IntType result_type; |
| #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION |
| static const bool has_fixed_range = true; |
| static const result_type min_value = ( c == 0 ? 1 : 0 ); |
| static const result_type max_value = m-1; |
| #else |
| BOOST_STATIC_CONSTANT(bool, has_fixed_range = false); |
| #endif |
| BOOST_STATIC_CONSTANT(IntType, multiplier = a); |
| BOOST_STATIC_CONSTANT(IntType, increment = c); |
| BOOST_STATIC_CONSTANT(IntType, modulus = m); |
| |
| // MSVC 6 and possibly others crash when encountering complicated integral |
| // constant expressions. Avoid the check for now. |
| // BOOST_STATIC_ASSERT(m == 0 || a < m); |
| // BOOST_STATIC_ASSERT(m == 0 || c < m); |
| |
| /** |
| * Constructs a linear_congruential generator, seeding it with @c x0. |
| */ |
| explicit linear_congruential(IntType x0 = 1) |
| { |
| seed(x0); |
| |
| // MSVC fails BOOST_STATIC_ASSERT with std::numeric_limits at class scope |
| #ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS |
| BOOST_STATIC_ASSERT(std::numeric_limits<IntType>::is_integer); |
| #endif |
| } |
| |
| /** |
| * Constructs a @c linear_congruential generator 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(It& first, It last) |
| { |
| seed(first, last); |
| } |
| |
| // compiler-generated copy constructor and assignment operator are fine |
| |
| /** |
| * 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). |
| */ |
| void seed(IntType x0 = 1) |
| { |
| // 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; |
| } |
| assert(_x >= (min)()); |
| assert(_x <= (max)()); |
| } |
| |
| /** |
| * seeds a @c linear_congruential generator 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) |
| { |
| if(first == last) |
| throw std::invalid_argument("linear_congruential::seed"); |
| seed(*first++); |
| } |
| |
| /** |
| * Returns the smallest value that the @c linear_congruential generator |
| * can produce. |
| */ |
| result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return c == 0 ? 1 : 0; } |
| /** |
| * Returns the largest value that the @c linear_congruential generator |
| * can produce. |
| */ |
| result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return modulus-1; } |
| |
| /** Returns the next value of the @c linear_congruential generator. */ |
| IntType operator()() |
| { |
| _x = const_mod<IntType, m>::mult_add(a, _x, c); |
| return _x; |
| } |
| |
| static bool validation(IntType x) { return val == x; } |
| |
| #ifdef BOOST_NO_OPERATORS_IN_NAMESPACE |
| |
| // Use a member function; Streamable concept not supported. |
| bool operator==(const linear_congruential& rhs) const |
| { return _x == rhs._x; } |
| bool operator!=(const linear_congruential& rhs) const |
| { return !(*this == rhs); } |
| |
| #else |
| friend bool operator==(const linear_congruential& x, |
| const linear_congruential& y) |
| { return x._x == y._x; } |
| friend bool operator!=(const linear_congruential& x, |
| const linear_congruential& y) |
| { return !(x == y); } |
| |
| #if !defined(BOOST_RANDOM_NO_STREAM_OPERATORS) && !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551)) |
| template<class CharT, class Traits> |
| friend std::basic_ostream<CharT,Traits>& |
| operator<<(std::basic_ostream<CharT,Traits>& os, |
| const linear_congruential& lcg) |
| { |
| return os << lcg._x; |
| } |
| |
| template<class CharT, class Traits> |
| friend std::basic_istream<CharT,Traits>& |
| operator>>(std::basic_istream<CharT,Traits>& is, |
| linear_congruential& lcg) |
| { |
| return is >> lcg._x; |
| } |
| |
| private: |
| #endif |
| #endif |
| |
| IntType _x; |
| }; |
| |
| // probably needs the "no native streams" caveat for STLPort |
| #if !defined(__SGI_STL_PORT) && BOOST_WORKAROUND(__GNUC__, == 2) |
| template<class IntType, IntType a, IntType c, IntType m, IntType val> |
| std::ostream& |
| operator<<(std::ostream& os, |
| const linear_congruential<IntType,a,c,m,val>& lcg) |
| { |
| return os << lcg._x; |
| } |
| |
| template<class IntType, IntType a, IntType c, IntType m, IntType val> |
| std::istream& |
| operator>>(std::istream& is, |
| linear_congruential<IntType,a,c,m,val>& lcg) |
| { |
| return is >> lcg._x; |
| } |
| #elif defined(BOOST_RANDOM_NO_STREAM_OPERATORS) || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551)) |
| template<class CharT, class Traits, class IntType, IntType a, IntType c, IntType m, IntType val> |
| std::basic_ostream<CharT,Traits>& |
| operator<<(std::basic_ostream<CharT,Traits>& os, |
| const linear_congruential<IntType,a,c,m,val>& lcg) |
| { |
| return os << lcg._x; |
| } |
| |
| template<class CharT, class Traits, class IntType, IntType a, IntType c, IntType m, IntType val> |
| std::basic_istream<CharT,Traits>& |
| operator>>(std::basic_istream<CharT,Traits>& is, |
| linear_congruential<IntType,a,c,m,val>& lcg) |
| { |
| return is >> lcg._x; |
| } |
| #endif |
| |
| #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION |
| // A definition is required even for integral static constants |
| template<class IntType, IntType a, IntType c, IntType m, IntType val> |
| const bool linear_congruential<IntType, a, c, m, val>::has_fixed_range; |
| template<class IntType, IntType a, IntType c, IntType m, IntType val> |
| const typename linear_congruential<IntType, a, c, m, val>::result_type linear_congruential<IntType, a, c, m, val>::min_value; |
| template<class IntType, IntType a, IntType c, IntType m, IntType val> |
| const typename linear_congruential<IntType, a, c, m, val>::result_type linear_congruential<IntType, a, c, m, val>::max_value; |
| template<class IntType, IntType a, IntType c, IntType m, IntType val> |
| const IntType linear_congruential<IntType,a,c,m,val>::modulus; |
| #endif |
| |
| } // namespace random |
| |
| // validation values from the publications |
| /** |
| * 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 random::linear_congruential<int32_t, 16807, 0, 2147483647, |
| 1043618065> 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 random::linear_congruential<int32_t, 48271, 0, 2147483647, |
| 399268537> 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 int32_t result_type; |
| #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION |
| static const bool has_fixed_range = true; |
| static const int32_t min_value = 0; |
| static const int32_t max_value = integer_traits<int32_t>::const_max; |
| #else |
| enum { has_fixed_range = false }; |
| #endif |
| /** |
| * Returns the smallest value that the generator can produce |
| */ |
| int32_t min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 0; } |
| /** |
| * Returns the largest value that the generator can produce |
| */ |
| int32_t max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return std::numeric_limits<int32_t>::max BOOST_PREVENT_MACRO_SUBSTITUTION (); } |
| |
| #ifdef BOOST_RANDOM_DOXYGEN |
| /** |
| * If T is an integral type smaller than int46_t, constructs |
| * a \rand48 generator with x(0) := (x0 << 16) | 0x330e. Otherwise |
| * constructs a \rand48 generator with x(0) = x0. |
| */ |
| template<class T> explicit rand48(T x0 = 1); |
| #else |
| rand48() : lcf(cnv(static_cast<int32_t>(1))) {} |
| template<class T> explicit rand48(T x0) : lcf(cnv(x0)) { } |
| #endif |
| template<class It> rand48(It& first, It last) : lcf(first, last) { } |
| |
| // compiler-generated copy ctor and assignment operator are fine |
| |
| #ifdef BOOST_RANDOM_DOXYGEN |
| /** |
| * If T is an integral type smaller than int46_t, changes |
| * the current value x(n) of the generator to (x0 << 16) | 0x330e. |
| * Otherwise changes the current value x(n) to x0. |
| */ |
| template<class T> void seed(T x0 = 1); |
| #else |
| void seed() { seed(static_cast<int32_t>(1)); } |
| template<class T> void seed(T x0) { lcf.seed(cnv(x0)); } |
| #endif |
| template<class It> void seed(It& first, It last) { lcf.seed(first,last); } |
| |
| /** |
| * Returns the next value of the generator. |
| */ |
| int32_t operator()() { return static_cast<int32_t>(lcf() >> 17); } |
| // by experiment from lrand48() |
| static bool validation(int32_t x) { return x == 1993516219; } |
| |
| #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 rand48& r) |
| { os << r.lcf; return os; } |
| |
| 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 |
| |
| friend bool operator==(const rand48& x, const rand48& y) |
| { return x.lcf == y.lcf; } |
| friend bool operator!=(const rand48& x, const rand48& y) |
| { return !(x == y); } |
| #else |
| // Use a member function; Streamable concept not supported. |
| bool operator==(const rand48& rhs) const |
| { return lcf == rhs.lcf; } |
| bool operator!=(const rand48& rhs) const |
| { return !(*this == rhs); } |
| #endif |
| private: |
| /// \cond hide_private_members |
| random::linear_congruential<uint64_t, |
| uint64_t(0xDEECE66DUL) | (uint64_t(0x5) << 32), // xxxxULL is not portable |
| 0xB, uint64_t(1)<<48, /* unknown */ 0> lcf; |
| template<class T> |
| static uint64_t cnv(T x) |
| { |
| if(sizeof(T) < sizeof(uint64_t)) { |
| return (static_cast<uint64_t>(x) << 16) | 0x330e; |
| } else { |
| return(static_cast<uint64_t>(x)); |
| } |
| } |
| static uint64_t cnv(float x) { return(static_cast<uint64_t>(x)); } |
| static uint64_t cnv(double x) { return(static_cast<uint64_t>(x)); } |
| static uint64_t cnv(long double x) { return(static_cast<uint64_t>(x)); } |
| /// \endcond |
| }; |
| #endif /* !BOOST_NO_INT64_T && !BOOST_NO_INTEGRAL_INT64_T */ |
| |
| } // namespace boost |
| |
| #include <boost/random/detail/enable_warnings.hpp> |
| |
| #endif // BOOST_RANDOM_LINEAR_CONGRUENTIAL_HPP |