[857] | 1 | /* boost random/uniform_on_sphere.hpp header file
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| 2 | *
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| 3 | * Copyright Jens Maurer 2000-2001
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| 4 | * Distributed under the Boost Software License, Version 1.0. (See
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| 5 | * accompanying file LICENSE_1_0.txt or copy at
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| 6 | * http://www.boost.org/LICENSE_1_0.txt)
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| 7 | *
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| 8 | * See http://www.boost.org for most recent version including documentation.
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| 9 | *
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| 10 | * $Id: uniform_on_sphere.hpp,v 1.11 2004/07/27 03:43:32 dgregor Exp $
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| 11 | *
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| 12 | * Revision history
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| 13 | * 2001-02-18 moved to individual header files
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| 14 | */
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| 15 |
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| 16 | #ifndef BOOST_RANDOM_UNIFORM_ON_SPHERE_HPP
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| 17 | #define BOOST_RANDOM_UNIFORM_ON_SPHERE_HPP
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| 18 |
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| 19 | #include <vector>
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| 20 | #include <algorithm> // std::transform
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| 21 | #include <functional> // std::bind2nd, std::divides
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| 22 | #include <boost/random/normal_distribution.hpp>
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| 23 |
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| 24 | namespace boost {
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| 25 |
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| 26 | template<class RealType = double, class Cont = std::vector<RealType> >
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| 27 | class uniform_on_sphere
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| 28 | {
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| 29 | public:
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| 30 | typedef RealType input_type;
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| 31 | typedef Cont result_type;
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| 32 |
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| 33 | explicit uniform_on_sphere(int dim = 2) : _container(dim), _dim(dim) { }
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| 34 |
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| 35 | // compiler-generated copy ctor and assignment operator are fine
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| 36 |
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| 37 | void reset() { _normal.reset(); }
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| 38 |
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| 39 | template<class Engine>
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| 40 | const result_type & operator()(Engine& eng)
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| 41 | {
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| 42 | RealType sqsum = 0;
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| 43 | for(typename Cont::iterator it = _container.begin();
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| 44 | it != _container.end();
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| 45 | ++it) {
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| 46 | RealType val = _normal(eng);
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| 47 | *it = val;
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| 48 | sqsum += val * val;
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| 49 | }
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| 50 | #ifndef BOOST_NO_STDC_NAMESPACE
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| 51 | using std::sqrt;
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| 52 | #endif
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| 53 | // for all i: result[i] /= sqrt(sqsum)
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| 54 | std::transform(_container.begin(), _container.end(), _container.begin(),
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| 55 | std::bind2nd(std::divides<RealType>(), sqrt(sqsum)));
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| 56 | return _container;
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| 57 | }
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| 58 |
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| 59 | #if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
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| 60 | template<class CharT, class Traits>
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| 61 | friend std::basic_ostream<CharT,Traits>&
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| 62 | operator<<(std::basic_ostream<CharT,Traits>& os, const uniform_on_sphere& sd)
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| 63 | {
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| 64 | os << sd._dim;
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| 65 | return os;
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| 66 | }
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| 67 |
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| 68 | template<class CharT, class Traits>
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| 69 | friend std::basic_istream<CharT,Traits>&
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| 70 | operator>>(std::basic_istream<CharT,Traits>& is, uniform_on_sphere& sd)
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| 71 | {
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| 72 | is >> std::ws >> sd._dim;
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| 73 | sd._container.resize(sd._dim);
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| 74 | return is;
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| 75 | }
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| 76 | #endif
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| 77 |
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| 78 | private:
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| 79 | normal_distribution<RealType> _normal;
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| 80 | result_type _container;
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| 81 | int _dim;
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| 82 | };
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| 83 |
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| 84 | } // namespace boost
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| 85 |
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| 86 | #endif // BOOST_RANDOM_UNIFORM_ON_SPHERE_HPP
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