| /* boost random/bernoulli_distribution.hpp header file |
| * |
| * Copyright Jens Maurer 2000-2001 |
| * Copyright Steven Watanabe 2011 |
| * 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_BERNOULLI_DISTRIBUTION_HPP |
| #define BOOST_RANDOM_BERNOULLI_DISTRIBUTION_HPP |
| |
| #include <iosfwd> |
| #include <boost/assert.hpp> |
| #include <boost/random/detail/config.hpp> |
| #include <boost/random/detail/operators.hpp> |
| |
| namespace boost { |
| namespace random { |
| |
| /** |
| * Instantiations of class template \bernoulli_distribution model a |
| * \random_distribution. Such a random distribution produces bool values |
| * distributed with probabilities P(true) = p and P(false) = 1-p. p is |
| * the parameter of the distribution. |
| */ |
| template<class RealType = double> |
| class bernoulli_distribution |
| { |
| public: |
| // In principle, this could work with both integer and floating-point |
| // types. Generating floating-point random numbers in the first |
| // place is probably more expensive, so use integer as input. |
| typedef int input_type; |
| typedef bool result_type; |
| |
| class param_type |
| { |
| public: |
| |
| typedef bernoulli_distribution distribution_type; |
| |
| /** |
| * Constructs the parameters of the distribution. |
| * |
| * Requires: 0 <= p <= 1 |
| */ |
| explicit param_type(RealType p_arg = RealType(0.5)) |
| : _p(p_arg) |
| { |
| BOOST_ASSERT(_p >= 0); |
| BOOST_ASSERT(_p <= 1); |
| } |
| |
| /** Returns the p parameter of the distribution. */ |
| RealType p() const { return _p; } |
| |
| /** Writes the parameters to a std::ostream. */ |
| BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, param_type, parm) |
| { |
| os << parm._p; |
| return os; |
| } |
| |
| /** Reads the parameters from a std::istream. */ |
| BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, param_type, parm) |
| { |
| is >> parm._p; |
| return is; |
| } |
| |
| /** Returns true if the two sets of parameters are equal. */ |
| BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(param_type, lhs, rhs) |
| { return lhs._p == rhs._p; } |
| |
| /** Returns true if the two sets of parameters are different. */ |
| BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(param_type) |
| |
| private: |
| RealType _p; |
| }; |
| |
| /** |
| * Constructs a \bernoulli_distribution object. |
| * p is the parameter of the distribution. |
| * |
| * Requires: 0 <= p <= 1 |
| */ |
| explicit bernoulli_distribution(const RealType& p_arg = RealType(0.5)) |
| : _p(p_arg) |
| { |
| BOOST_ASSERT(_p >= 0); |
| BOOST_ASSERT(_p <= 1); |
| } |
| /** |
| * Constructs \bernoulli_distribution from its parameters |
| */ |
| explicit bernoulli_distribution(const param_type& parm) |
| : _p(parm.p()) {} |
| |
| // compiler-generated copy ctor and assignment operator are fine |
| |
| /** |
| * Returns: The "p" parameter of the distribution. |
| */ |
| RealType p() const { return _p; } |
| |
| /** Returns the smallest value that the distribution can produce. */ |
| bool min BOOST_PREVENT_MACRO_SUBSTITUTION () const |
| { return false; } |
| /** Returns the largest value that the distribution can produce. */ |
| bool max BOOST_PREVENT_MACRO_SUBSTITUTION () const |
| { return true; } |
| |
| /** Returns the parameters of the distribution. */ |
| param_type param() const { return param_type(_p); } |
| /** Sets the parameters of the distribution. */ |
| void param(const param_type& parm) { _p = parm.p(); } |
| |
| /** |
| * Effects: Subsequent uses of the distribution do not depend |
| * on values produced by any engine prior to invoking reset. |
| */ |
| void reset() { } |
| |
| /** |
| * Returns: a random variate distributed according to the |
| * \bernoulli_distribution. |
| */ |
| template<class Engine> |
| bool operator()(Engine& eng) const |
| { |
| if(_p == RealType(0)) |
| return false; |
| else |
| return RealType(eng() - (eng.min)()) <= _p * RealType((eng.max)()-(eng.min)()); |
| } |
| |
| /** |
| * Returns: a random variate distributed according to the |
| * \bernoulli_distribution with parameters specified by param. |
| */ |
| template<class Engine> |
| bool operator()(Engine& eng, const param_type& parm) const |
| { |
| return bernoulli_distribution(parm)(eng); |
| } |
| |
| /** |
| * Writes the parameters of the distribution to a @c std::ostream. |
| */ |
| BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, bernoulli_distribution, bd) |
| { |
| os << bd._p; |
| return os; |
| } |
| |
| /** |
| * Reads the parameters of the distribution from a @c std::istream. |
| */ |
| BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, bernoulli_distribution, bd) |
| { |
| is >> bd._p; |
| return is; |
| } |
| |
| /** |
| * Returns true iff the two distributions will produce identical |
| * sequences of values given equal generators. |
| */ |
| BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(bernoulli_distribution, lhs, rhs) |
| { return lhs._p == rhs._p; } |
| |
| /** |
| * Returns true iff the two distributions will produce different |
| * sequences of values given equal generators. |
| */ |
| BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(bernoulli_distribution) |
| |
| private: |
| RealType _p; |
| }; |
| |
| } // namespace random |
| |
| using random::bernoulli_distribution; |
| |
| } // namespace boost |
| |
| #endif // BOOST_RANDOM_BERNOULLI_DISTRIBUTION_HPP |