/* 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 |