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b32b8144 | 1 | // Copyright Louis Dionne 2013-2017 |
7c673cae FG |
2 | // Distributed under the Boost Software License, Version 1.0. |
3 | // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) | |
4 | ||
5 | #ifndef BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_DET_HPP | |
6 | #define BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_DET_HPP | |
7 | ||
8 | #include <boost/hana/equal.hpp> | |
9 | #include <boost/hana/eval_if.hpp> | |
10 | #include <boost/hana/front.hpp> | |
11 | #include <boost/hana/functional/always.hpp> | |
12 | #include <boost/hana/functional/fix.hpp> | |
13 | #include <boost/hana/functional/flip.hpp> | |
14 | #include <boost/hana/functional/on.hpp> | |
15 | #include <boost/hana/functional/partial.hpp> | |
16 | #include <boost/hana/integral_constant.hpp> | |
17 | #include <boost/hana/plus.hpp> | |
18 | #include <boost/hana/power.hpp> | |
19 | #include <boost/hana/range.hpp> | |
20 | #include <boost/hana/remove_at.hpp> | |
21 | #include <boost/hana/transform.hpp> | |
22 | #include <boost/hana/tuple.hpp> | |
23 | #include <boost/hana/unpack.hpp> | |
24 | ||
25 | #include <utility> | |
26 | ||
27 | #include "matrix.hpp" | |
28 | ||
29 | ||
30 | namespace cppcon { | |
31 | namespace hana = boost::hana; | |
32 | auto det = hana::fix([](auto det, auto&& m) -> decltype(auto) { | |
33 | auto matrix_minor = [=](auto&& m, auto i, auto j) -> decltype(auto) { | |
34 | return det(hana::unpack( | |
35 | hana::transform( | |
36 | hana::remove_at(rows(std::forward<decltype(m)>(m)), i), | |
37 | hana::partial(hana::flip(hana::remove_at), j) | |
38 | ), | |
39 | matrix | |
40 | )); | |
41 | }; | |
42 | ||
43 | auto cofactor = [=](auto&& m, auto i, auto j) { | |
44 | return hana::power(hana::int_c<-1>, hana::plus(i, j)) * | |
45 | matrix_minor(std::forward<decltype(m)>(m), i, j); | |
46 | }; | |
47 | ||
48 | return hana::eval_if(m.size() == hana::size_c<1>, | |
49 | hana::always(m.at(hana::size_c<0>, hana::size_c<0>)), | |
50 | [=](auto _) { | |
51 | auto cofactors_1st_row = hana::unpack(_(hana::make_range)(hana::size_c<0>, m.ncolumns()), | |
52 | hana::on(hana::make_tuple, hana::partial(cofactor, m, hana::size_c<0>)) | |
53 | ); | |
54 | return detail::tuple_scalar_product(hana::front(rows(m)), cofactors_1st_row); | |
55 | } | |
56 | ); | |
57 | }); | |
58 | } // end namespace cppcon | |
59 | ||
60 | #endif // !BOOST_HANA_EXAMPLE_CPPCON_2014_MATRIX_DET_HPP |