109 lines
3.3 KiB
C++
109 lines
3.3 KiB
C++
/* boost random/uniform_real.hpp header file
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*
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* Copyright Jens Maurer 2000-2001
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* Distributed under the Boost Software License, Version 1.0. (See
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* accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* See http://www.boost.org for most recent version including documentation.
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*
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* $Id: uniform_real.hpp 60755 2010-03-22 00:45:06Z steven_watanabe $
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*
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* Revision history
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* 2001-04-08 added min<max assertion (N. Becker)
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* 2001-02-18 moved to individual header files
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*/
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#ifndef BOOST_RANDOM_UNIFORM_REAL_HPP
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#define BOOST_RANDOM_UNIFORM_REAL_HPP
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#include <cassert>
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#include <iostream>
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#include <boost/config.hpp>
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#include <boost/limits.hpp>
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#include <boost/static_assert.hpp>
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#include <boost/random/detail/config.hpp>
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namespace boost {
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/**
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* The distribution function uniform_real models a random distribution.
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* On each invocation, it returns a random floating-point value uniformly
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* distributed in the range [min..max). The value is computed using
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* std::numeric_limits<RealType>::digits random binary digits, i.e.
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* the mantissa of the floating-point value is completely filled with
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* random bits.
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*
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* Note: The current implementation is buggy, because it may not fill
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* all of the mantissa with random bits.
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*/
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template<class RealType = double>
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class uniform_real
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{
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public:
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typedef RealType input_type;
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typedef RealType result_type;
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/**
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* Constructs a uniform_real object. @c min and @c max are the
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* parameters of the distribution.
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*
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* Requires: min <= max
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*/
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explicit uniform_real(RealType min_arg = RealType(0),
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RealType max_arg = RealType(1))
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: _min(min_arg), _max(max_arg)
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{
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#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
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BOOST_STATIC_ASSERT(!std::numeric_limits<RealType>::is_integer);
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#endif
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assert(min_arg <= max_arg);
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}
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// compiler-generated copy ctor and assignment operator are fine
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/**
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* Returns: The "min" parameter of the distribution
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*/
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result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return _min; }
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/**
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* Returns: The "max" parameter of the distribution
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*/
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result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return _max; }
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void reset() { }
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template<class Engine>
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result_type operator()(Engine& eng) {
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result_type numerator = static_cast<result_type>(eng() - eng.min BOOST_PREVENT_MACRO_SUBSTITUTION());
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result_type divisor = static_cast<result_type>(eng.max BOOST_PREVENT_MACRO_SUBSTITUTION() - eng.min BOOST_PREVENT_MACRO_SUBSTITUTION());
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assert(divisor > 0);
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assert(numerator >= 0 && numerator <= divisor);
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return numerator / divisor * (_max - _min) + _min;
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}
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#ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
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template<class CharT, class Traits>
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friend std::basic_ostream<CharT,Traits>&
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operator<<(std::basic_ostream<CharT,Traits>& os, const uniform_real& ud)
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{
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os << ud._min << " " << ud._max;
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return os;
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}
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template<class CharT, class Traits>
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friend std::basic_istream<CharT,Traits>&
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operator>>(std::basic_istream<CharT,Traits>& is, uniform_real& ud)
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{
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is >> std::ws >> ud._min >> std::ws >> ud._max;
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return is;
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}
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#endif
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private:
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RealType _min, _max;
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};
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} // namespace boost
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#endif // BOOST_RANDOM_UNIFORM_REAL_HPP
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