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/* boost random/bernoulli_distribution.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: bernoulli_distribution.hpp,v 1.19 2004/07/27 03:43:32 dgregor Exp $
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*
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* Revision history
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* 2001-02-18 moved to individual header files
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*/
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#ifndef BOOST_RANDOM_BERNOULLI_DISTRIBUTION_HPP
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#define BOOST_RANDOM_BERNOULLI_DISTRIBUTION_HPP
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#include <cassert>
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#include <iostream>
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namespace boost {
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// Bernoulli distribution: p(true) = p, p(false) = 1-p (boolean)
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template<class RealType = double>
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class bernoulli_distribution
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{
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public:
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// In principle, this could work with both integer and floating-point
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// types. Generating floating-point random numbers in the first
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// place is probably more expensive, so use integer as input.
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typedef int input_type;
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typedef bool result_type;
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explicit bernoulli_distribution(const RealType& p = RealType(0.5))
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: _p(p)
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{
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assert(p >= 0);
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assert(p <= 1);
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}
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// compiler-generated copy ctor and assignment operator are fine
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RealType p() const { return _p; }
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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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{
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if(_p == RealType(0))
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return false;
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else
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return RealType(eng() - (eng.min)()) <= _p * RealType((eng.max)()-(eng.min)());
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}
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#if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
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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 bernoulli_distribution& bd)
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{
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os << bd._p;
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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, bernoulli_distribution& bd)
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{
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is >> std::ws >> bd._p;
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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 _p;
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};
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} // namespace boost
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#endif // BOOST_RANDOM_BERNOULLI_DISTRIBUTION_HPP
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