Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // weighted_moment.hpp
Chris@16: //
Chris@16: //  Copyright 2006, Eric Niebler, Olivier Gygi. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_ACCUMULATORS_STATISTICS_WEIGHTED_MOMENT_HPP_EAN_15_11_2005
Chris@16: #define BOOST_ACCUMULATORS_STATISTICS_WEIGHTED_MOMENT_HPP_EAN_15_11_2005
Chris@16: 
Chris@16: #include <boost/config/no_tr1/cmath.hpp>
Chris@16: #include <boost/mpl/int.hpp>
Chris@16: #include <boost/mpl/assert.hpp>
Chris@16: #include <boost/mpl/placeholders.hpp>
Chris@16: #include <boost/preprocessor/arithmetic/inc.hpp>
Chris@16: #include <boost/preprocessor/repetition/repeat_from_to.hpp>
Chris@16: #include <boost/preprocessor/repetition/enum_trailing_params.hpp>
Chris@16: #include <boost/preprocessor/repetition/enum_trailing_binary_params.hpp>
Chris@16: #include <boost/accumulators/framework/accumulator_base.hpp>
Chris@16: #include <boost/accumulators/framework/extractor.hpp>
Chris@16: #include <boost/accumulators/numeric/functional.hpp>
Chris@16: #include <boost/accumulators/framework/parameters/sample.hpp>
Chris@16: #include <boost/accumulators/framework/depends_on.hpp>
Chris@16: #include <boost/accumulators/statistics_fwd.hpp>
Chris@16: #include <boost/accumulators/statistics/count.hpp>
Chris@16: #include <boost/accumulators/statistics/moment.hpp> // for pow()
Chris@16: #include <boost/accumulators/statistics/sum.hpp>
Chris@16: 
Chris@16: namespace boost { namespace accumulators
Chris@16: {
Chris@16: 
Chris@16: namespace impl
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////////
Chris@16:     // weighted_moment_impl
Chris@16:     template<typename N, typename Sample, typename Weight>
Chris@16:     struct weighted_moment_impl
Chris@16:       : accumulator_base // TODO: also depends_on sum of powers
Chris@16:     {
Chris@16:         BOOST_MPL_ASSERT_RELATION(N::value, >, 0);
Chris@16:         typedef typename numeric::functional::multiplies<Sample, Weight>::result_type weighted_sample;
Chris@16:         // for boost::result_of
Chris@16:         typedef typename numeric::functional::fdiv<weighted_sample, Weight>::result_type result_type;
Chris@16: 
Chris@16:         template<typename Args>
Chris@16:         weighted_moment_impl(Args const &args)
Chris@16:           : sum(args[sample | Sample()] * numeric::one<Weight>::value)
Chris@16:         {
Chris@16:         }
Chris@16: 
Chris@16:         template<typename Args>
Chris@16:         void operator ()(Args const &args)
Chris@16:         {
Chris@16:             this->sum += args[weight] * numeric::pow(args[sample], N());
Chris@16:         }
Chris@16: 
Chris@16:         template<typename Args>
Chris@16:         result_type result(Args const &args) const
Chris@16:         {
Chris@16:             return numeric::fdiv(this->sum, sum_of_weights(args));
Chris@16:         }
Chris@16: 
Chris@16:     private:
Chris@16:         weighted_sample sum;
Chris@16:     };
Chris@16: 
Chris@16: } // namespace impl
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // tag::weighted_moment
Chris@16: //
Chris@16: namespace tag
Chris@16: {
Chris@16:     template<int N>
Chris@16:     struct weighted_moment
Chris@16:       : depends_on<count, sum_of_weights>
Chris@16:     {
Chris@16:         /// INTERNAL ONLY
Chris@16:         ///
Chris@16:         typedef accumulators::impl::weighted_moment_impl<mpl::int_<N>, mpl::_1, mpl::_2> impl;
Chris@16:     };
Chris@16: }
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // extract::weighted_moment
Chris@16: //
Chris@16: namespace extract
Chris@16: {
Chris@16:     BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, weighted_moment, (int))
Chris@16: }
Chris@16: 
Chris@16: using extract::weighted_moment;
Chris@16: 
Chris@16: }} // namespace boost::accumulators
Chris@16: 
Chris@16: #endif