111 lines
3.0 KiB
C++
111 lines
3.0 KiB
C++
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// Copyright John Maddock 2007.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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/*
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This header defines two traits classes, both in namespace boost::math::tools.
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is_distribution<D>::value is true iff D has overloaded "cdf" and
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"quantile" functions, plus member typedefs value_type and policy_type.
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It's not much of a definitive test frankly,
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but if it looks like a distribution and quacks like a distribution
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then it must be a distribution.
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is_scaled_distribution<D>::value is true iff D is a distribution
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as defined above, and has member functions "scale" and "location".
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*/
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#ifndef BOOST_STATS_IS_DISTRIBUTION_HPP
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#define BOOST_STATS_IS_DISTRIBUTION_HPP
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#ifdef _MSC_VER
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#pragma once
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#endif
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#include <boost/mpl/has_xxx.hpp>
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#include <boost/type_traits/integral_constant.hpp>
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namespace boost{ namespace math{ namespace tools{
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namespace detail{
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BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_value_type, value_type, true)
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BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_policy_type, policy_type, true)
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template<class D>
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char cdf(const D& ...);
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template<class D>
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char quantile(const D& ...);
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template <class D>
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struct has_cdf
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{
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static D d;
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BOOST_STATIC_CONSTANT(bool, value = sizeof(cdf(d, 0.0f)) != 1);
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};
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template <class D>
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struct has_quantile
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{
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static D d;
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BOOST_STATIC_CONSTANT(bool, value = sizeof(quantile(d, 0.0f)) != 1);
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};
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template <class D>
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struct is_distribution_imp
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{
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BOOST_STATIC_CONSTANT(bool, value =
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has_quantile<D>::value
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&& has_cdf<D>::value
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&& has_value_type<D>::value
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&& has_policy_type<D>::value);
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};
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template <class sig, sig val>
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struct result_tag{};
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template <class D>
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double test_has_location(const volatile result_tag<typename D::value_type (D::*)()const, &D::location>*);
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template <class D>
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char test_has_location(...);
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template <class D>
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double test_has_scale(const volatile result_tag<typename D::value_type (D::*)()const, &D::scale>*);
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template <class D>
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char test_has_scale(...);
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template <class D, bool b>
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struct is_scaled_distribution_helper
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{
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BOOST_STATIC_CONSTANT(bool, value = false);
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};
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template <class D>
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struct is_scaled_distribution_helper<D, true>
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{
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BOOST_STATIC_CONSTANT(bool, value =
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(sizeof(test_has_location<D>(0)) != 1)
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&&
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(sizeof(test_has_scale<D>(0)) != 1));
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};
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template <class D>
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struct is_scaled_distribution_imp
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{
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BOOST_STATIC_CONSTANT(bool, value = (::boost::math::tools::detail::is_scaled_distribution_helper<D, ::boost::math::tools::detail::is_distribution_imp<D>::value>::value));
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};
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} // namespace detail
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template <class T> struct is_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_distribution_imp<T>::value> {};
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template <class T> struct is_scaled_distribution : public boost::integral_constant<bool, ::boost::math::tools::detail::is_scaled_distribution_imp<T>::value> {};
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}}}
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#endif
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