1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/epoc32/include/stdapis/boost/random/triangle_distribution.hpp Tue Mar 16 16:12:26 2010 +0000
1.3 @@ -0,0 +1,101 @@
1.4 +/* boost random/triangle_distribution.hpp header file
1.5 + *
1.6 + * Copyright Jens Maurer 2000-2001
1.7 + * Distributed under the Boost Software License, Version 1.0. (See
1.8 + * accompanying file LICENSE_1_0.txt or copy at
1.9 + * http://www.boost.org/LICENSE_1_0.txt)
1.10 + *
1.11 + * See http://www.boost.org for most recent version including documentation.
1.12 + *
1.13 + * $Id: triangle_distribution.hpp,v 1.11 2004/07/27 03:43:32 dgregor Exp $
1.14 + *
1.15 + * Revision history
1.16 + * 2001-02-18 moved to individual header files
1.17 + */
1.18 +
1.19 +#ifndef BOOST_RANDOM_TRIANGLE_DISTRIBUTION_HPP
1.20 +#define BOOST_RANDOM_TRIANGLE_DISTRIBUTION_HPP
1.21 +
1.22 +#include <cmath>
1.23 +#include <cassert>
1.24 +#include <boost/random/uniform_01.hpp>
1.25 +
1.26 +namespace boost {
1.27 +
1.28 +// triangle distribution, with a smallest, b most probable, and c largest
1.29 +// value.
1.30 +template<class RealType = double>
1.31 +class triangle_distribution
1.32 +{
1.33 +public:
1.34 + typedef RealType input_type;
1.35 + typedef RealType result_type;
1.36 +
1.37 + explicit triangle_distribution(result_type a = result_type(0),
1.38 + result_type b = result_type(0.5),
1.39 + result_type c = result_type(1))
1.40 + : _a(a), _b(b), _c(c)
1.41 + {
1.42 + assert(_a <= _b && _b <= _c);
1.43 + init();
1.44 + }
1.45 +
1.46 + // compiler-generated copy ctor and assignment operator are fine
1.47 + result_type a() const { return _a; }
1.48 + result_type b() const { return _b; }
1.49 + result_type c() const { return _c; }
1.50 +
1.51 + void reset() { }
1.52 +
1.53 + template<class Engine>
1.54 + result_type operator()(Engine& eng)
1.55 + {
1.56 +#ifndef BOOST_NO_STDC_NAMESPACE
1.57 + using std::sqrt;
1.58 +#endif
1.59 + result_type u = eng();
1.60 + if( u <= q1 )
1.61 + return _a + p1*sqrt(u);
1.62 + else
1.63 + return _c - d3*sqrt(d2*u-d1);
1.64 + }
1.65 +
1.66 +#if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
1.67 + template<class CharT, class Traits>
1.68 + friend std::basic_ostream<CharT,Traits>&
1.69 + operator<<(std::basic_ostream<CharT,Traits>& os, const triangle_distribution& td)
1.70 + {
1.71 + os << td._a << " " << td._b << " " << td._c;
1.72 + return os;
1.73 + }
1.74 +
1.75 + template<class CharT, class Traits>
1.76 + friend std::basic_istream<CharT,Traits>&
1.77 + operator>>(std::basic_istream<CharT,Traits>& is, triangle_distribution& td)
1.78 + {
1.79 + is >> std::ws >> td._a >> std::ws >> td._b >> std::ws >> td._c;
1.80 + td.init();
1.81 + return is;
1.82 + }
1.83 +#endif
1.84 +
1.85 +private:
1.86 + void init()
1.87 + {
1.88 +#ifndef BOOST_NO_STDC_NAMESPACE
1.89 + using std::sqrt;
1.90 +#endif
1.91 + d1 = _b - _a;
1.92 + d2 = _c - _a;
1.93 + d3 = sqrt(_c - _b);
1.94 + q1 = d1 / d2;
1.95 + p1 = sqrt(d1 * d2);
1.96 + }
1.97 +
1.98 + result_type _a, _b, _c;
1.99 + result_type d1, d2, d3, q1, p1;
1.100 +};
1.101 +
1.102 +} // namespace boost
1.103 +
1.104 +#endif // BOOST_RANDOM_TRIANGLE_DISTRIBUTION_HPP