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125 lines
3.2 KiB
125 lines
3.2 KiB
/////////////////////////////////////////////////////////////////////////////// |
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// moment.hpp |
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// |
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// Copyright 2005 Eric Niebler. Distributed under the Boost |
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// 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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#ifndef BOOST_ACCUMULATORS_STATISTICS_MOMENT_HPP_EAN_15_11_2005 |
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#define BOOST_ACCUMULATORS_STATISTICS_MOMENT_HPP_EAN_15_11_2005 |
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#include <boost/config/no_tr1/cmath.hpp> |
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#include <boost/mpl/int.hpp> |
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#include <boost/mpl/assert.hpp> |
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#include <boost/mpl/placeholders.hpp> |
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#include <boost/accumulators/framework/accumulator_base.hpp> |
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#include <boost/accumulators/framework/extractor.hpp> |
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#include <boost/accumulators/numeric/functional.hpp> |
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#include <boost/accumulators/framework/parameters/sample.hpp> |
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#include <boost/accumulators/framework/depends_on.hpp> |
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#include <boost/accumulators/statistics_fwd.hpp> |
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#include <boost/accumulators/statistics/count.hpp> |
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namespace boost { namespace numeric |
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{ |
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/// INTERNAL ONLY |
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/// |
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template<typename T> |
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T const &pow(T const &x, mpl::int_<1>) |
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{ |
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return x; |
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} |
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/// INTERNAL ONLY |
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/// |
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template<typename T, int N> |
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T pow(T const &x, mpl::int_<N>) |
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{ |
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using namespace operators; |
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T y = numeric::pow(x, mpl::int_<N/2>()); |
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T z = y * y; |
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return (N % 2) ? (z * x) : z; |
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} |
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}} |
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namespace boost { namespace accumulators |
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{ |
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namespace impl |
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{ |
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/////////////////////////////////////////////////////////////////////////////// |
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// moment_impl |
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template<typename N, typename Sample> |
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struct moment_impl |
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: accumulator_base // TODO: also depends_on sum of powers |
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{ |
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BOOST_MPL_ASSERT_RELATION(N::value, >, 0); |
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// for boost::result_of |
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typedef typename numeric::functional::average<Sample, std::size_t>::result_type result_type; |
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template<typename Args> |
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moment_impl(Args const &args) |
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: sum(args[sample | Sample()]) |
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{ |
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} |
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template<typename Args> |
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void operator ()(Args const &args) |
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{ |
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this->sum += numeric::pow(args[sample], N()); |
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} |
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template<typename Args> |
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result_type result(Args const &args) const |
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{ |
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return numeric::average(this->sum, count(args)); |
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} |
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private: |
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Sample sum; |
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}; |
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} // namespace impl |
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/////////////////////////////////////////////////////////////////////////////// |
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// tag::moment |
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// |
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namespace tag |
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{ |
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template<int N> |
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struct moment |
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: depends_on<count> |
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{ |
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/// INTERNAL ONLY |
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/// |
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typedef accumulators::impl::moment_impl<mpl::int_<N>, mpl::_1> impl; |
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}; |
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} |
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/////////////////////////////////////////////////////////////////////////////// |
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// extract::moment |
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// |
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namespace extract |
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{ |
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BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, moment, (int)) |
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} |
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using extract::moment; |
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// So that moment<N> can be automatically substituted with |
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// weighted_moment<N> when the weight parameter is non-void |
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template<int N> |
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struct as_weighted_feature<tag::moment<N> > |
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{ |
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typedef tag::weighted_moment<N> type; |
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}; |
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template<int N> |
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struct feature_of<tag::weighted_moment<N> > |
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: feature_of<tag::moment<N> > |
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{ |
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}; |
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}} // namespace boost::accumulators |
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#endif
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