williamr@2: /* boost random/triangle_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: triangle_distribution.hpp,v 1.11 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_TRIANGLE_DISTRIBUTION_HPP williamr@2: #define BOOST_RANDOM_TRIANGLE_DISTRIBUTION_HPP williamr@2: williamr@2: #include williamr@2: #include williamr@2: #include williamr@2: williamr@2: namespace boost { williamr@2: williamr@2: // triangle distribution, with a smallest, b most probable, and c largest williamr@2: // value. williamr@2: template williamr@2: class triangle_distribution williamr@2: { williamr@2: public: williamr@2: typedef RealType input_type; williamr@2: typedef RealType result_type; williamr@2: williamr@2: explicit triangle_distribution(result_type a = result_type(0), williamr@2: result_type b = result_type(0.5), williamr@2: result_type c = result_type(1)) williamr@2: : _a(a), _b(b), _c(c) williamr@2: { williamr@2: assert(_a <= _b && _b <= _c); williamr@2: init(); williamr@2: } williamr@2: williamr@2: // compiler-generated copy ctor and assignment operator are fine williamr@2: result_type a() const { return _a; } williamr@2: result_type b() const { return _b; } williamr@2: result_type c() const { return _c; } williamr@2: williamr@2: void reset() { } williamr@2: williamr@2: template williamr@2: result_type operator()(Engine& eng) williamr@2: { williamr@2: #ifndef BOOST_NO_STDC_NAMESPACE williamr@2: using std::sqrt; williamr@2: #endif williamr@2: result_type u = eng(); williamr@2: if( u <= q1 ) williamr@2: return _a + p1*sqrt(u); williamr@2: else williamr@2: return _c - d3*sqrt(d2*u-d1); 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 triangle_distribution& td) williamr@2: { williamr@2: os << td._a << " " << td._b << " " << td._c; williamr@2: return os; williamr@2: } williamr@2: williamr@2: template williamr@2: friend std::basic_istream& williamr@2: operator>>(std::basic_istream& is, triangle_distribution& td) williamr@2: { williamr@2: is >> std::ws >> td._a >> std::ws >> td._b >> std::ws >> td._c; williamr@2: td.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: using std::sqrt; williamr@2: #endif williamr@2: d1 = _b - _a; williamr@2: d2 = _c - _a; williamr@2: d3 = sqrt(_c - _b); williamr@2: q1 = d1 / d2; williamr@2: p1 = sqrt(d1 * d2); williamr@2: } williamr@2: williamr@2: result_type _a, _b, _c; williamr@2: result_type d1, d2, d3, q1, p1; williamr@2: }; williamr@2: williamr@2: } // namespace boost williamr@2: williamr@2: #endif // BOOST_RANDOM_TRIANGLE_DISTRIBUTION_HPP