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-rw-r--r-- | src/boost/libs/hana/example/cppcon_2014/matrix/det.hpp | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/cppcon_2014/matrix/det.hpp b/src/boost/libs/hana/example/cppcon_2014/matrix/det.hpp new file mode 100644 index 000000000..f499fda7e --- /dev/null +++ b/src/boost/libs/hana/example/cppcon_2014/matrix/det.hpp @@ -0,0 +1,60 @@ +// Copyright Louis Dionne 2013-2017 +// Distributed under the Boost Software License, Version 1.0. +// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) + +#ifndef BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_DET_HPP +#define BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_DET_HPP + +#include <boost/hana/equal.hpp> +#include <boost/hana/eval_if.hpp> +#include <boost/hana/front.hpp> +#include <boost/hana/functional/always.hpp> +#include <boost/hana/functional/fix.hpp> +#include <boost/hana/functional/flip.hpp> +#include <boost/hana/functional/on.hpp> +#include <boost/hana/functional/partial.hpp> +#include <boost/hana/integral_constant.hpp> +#include <boost/hana/plus.hpp> +#include <boost/hana/power.hpp> +#include <boost/hana/range.hpp> +#include <boost/hana/remove_at.hpp> +#include <boost/hana/transform.hpp> +#include <boost/hana/tuple.hpp> +#include <boost/hana/unpack.hpp> + +#include <utility> + +#include "matrix.hpp" + + +namespace cppcon { + namespace hana = boost::hana; + auto det = hana::fix([](auto det, auto&& m) -> decltype(auto) { + auto matrix_minor = [=](auto&& m, auto i, auto j) -> decltype(auto) { + return det(hana::unpack( + hana::transform( + hana::remove_at(rows(std::forward<decltype(m)>(m)), i), + hana::partial(hana::flip(hana::remove_at), j) + ), + matrix + )); + }; + + auto cofactor = [=](auto&& m, auto i, auto j) { + return hana::power(hana::int_c<-1>, hana::plus(i, j)) * + matrix_minor(std::forward<decltype(m)>(m), i, j); + }; + + return hana::eval_if(m.size() == hana::size_c<1>, + hana::always(m.at(hana::size_c<0>, hana::size_c<0>)), + [=](auto _) { + auto cofactors_1st_row = hana::unpack(_(hana::make_range)(hana::size_c<0>, m.ncolumns()), + hana::on(hana::make_tuple, hana::partial(cofactor, m, hana::size_c<0>)) + ); + return detail::tuple_scalar_product(hana::front(rows(m)), cofactors_1st_row); + } + ); + }); +} // end namespace cppcon + +#endif // !BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_DET_HPP |