williamr@2: /* boost random/lognormal_distribution.hpp header file williamr@2: * williamr@2: * Copyright Jens Maurer 2000-2001 williamr@2: * Distributed under the Boost Software License, Version 1.0. (See williamr@2: * accompanying file LICENSE_1_0.txt or copy at williamr@2: * http://www.boost.org/LICENSE_1_0.txt) williamr@2: * williamr@2: * See http://www.boost.org for most recent version including documentation. williamr@2: * williamr@2: * $Id: lognormal_distribution.hpp,v 1.16 2004/07/27 03:43:32 dgregor Exp $ williamr@2: * williamr@2: * Revision history williamr@2: * 2001-02-18 moved to individual header files williamr@2: */ williamr@2: williamr@2: #ifndef BOOST_RANDOM_LOGNORMAL_DISTRIBUTION_HPP williamr@2: #define BOOST_RANDOM_LOGNORMAL_DISTRIBUTION_HPP williamr@2: williamr@2: #include // std::exp, std::sqrt williamr@2: #include williamr@2: #include williamr@2: #include williamr@2: #include williamr@2: #include williamr@2: williamr@2: #ifdef BOOST_NO_STDC_NAMESPACE williamr@2: namespace std { williamr@2: using ::log; williamr@2: using ::sqrt; williamr@2: } williamr@2: #endif williamr@2: williamr@2: namespace boost { williamr@2: williamr@2: #if defined(__GNUC__) && (__GNUC__ < 3) williamr@2: // Special gcc workaround: gcc 2.95.x ignores using-declarations williamr@2: // in template classes (confirmed by gcc author Martin v. Loewis) williamr@2: using std::sqrt; williamr@2: using std::exp; williamr@2: #endif williamr@2: williamr@2: template williamr@2: class lognormal_distribution williamr@2: { williamr@2: public: williamr@2: typedef typename normal_distribution::input_type input_type; williamr@2: typedef RealType result_type; williamr@2: williamr@2: #ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS williamr@2: BOOST_STATIC_ASSERT(!std::numeric_limits::is_integer); williamr@2: #endif williamr@2: williamr@2: explicit lognormal_distribution(result_type mean = result_type(1), williamr@2: result_type sigma = result_type(1)) williamr@2: : _mean(mean), _sigma(sigma) williamr@2: { williamr@2: assert(mean > result_type(0)); williamr@2: init(); williamr@2: } williamr@2: williamr@2: // compiler-generated copy ctor and assignment operator are fine williamr@2: williamr@2: RealType& mean() const { return _mean; } williamr@2: RealType& sigma() const { return _sigma; } williamr@2: void reset() { _normal.reset(); } williamr@2: williamr@2: template williamr@2: result_type operator()(Engine& eng) williamr@2: { williamr@2: #ifndef BOOST_NO_STDC_NAMESPACE williamr@2: // allow for Koenig lookup williamr@2: using std::exp; williamr@2: #endif williamr@2: return exp(_normal(eng) * _nsigma + _nmean); williamr@2: } williamr@2: williamr@2: #if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) williamr@2: template williamr@2: friend std::basic_ostream& williamr@2: operator<<(std::basic_ostream& os, const lognormal_distribution& ld) williamr@2: { williamr@2: os << ld._normal << " " << ld._mean << " " << ld._sigma; williamr@2: return os; williamr@2: } williamr@2: williamr@2: template williamr@2: friend std::basic_istream& williamr@2: operator>>(std::basic_istream& is, lognormal_distribution& ld) williamr@2: { williamr@2: is >> std::ws >> ld._normal >> std::ws >> ld._mean >> std::ws >> ld._sigma; williamr@2: ld.init(); williamr@2: return is; williamr@2: } williamr@2: #endif williamr@2: williamr@2: private: williamr@2: void init() williamr@2: { williamr@2: #ifndef BOOST_NO_STDC_NAMESPACE williamr@2: // allow for Koenig lookup williamr@2: using std::exp; using std::log; using std::sqrt; williamr@2: #endif williamr@2: _nmean = log(_mean*_mean/sqrt(_sigma*_sigma + _mean*_mean)); williamr@2: _nsigma = sqrt(log(_sigma*_sigma/_mean/_mean+result_type(1))); williamr@2: } williamr@2: williamr@2: RealType _mean, _sigma; williamr@2: RealType _nmean, _nsigma; williamr@2: normal_distribution _normal; williamr@2: }; williamr@2: williamr@2: } // namespace boost williamr@2: williamr@2: #endif // BOOST_RANDOM_LOGNORMAL_DISTRIBUTION_HPP