mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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104 lines
4.2 KiB
C++
104 lines
4.2 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2017 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_NUMERIC_DFT_DETAIL_DFT_ELEMENT_GEN_HPP
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#define SPROUT_NUMERIC_DFT_DETAIL_DFT_ELEMENT_GEN_HPP
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#include <iterator>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/iterator/operation.hpp>
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#include <sprout/math/sin.hpp>
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#include <sprout/math/cos.hpp>
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namespace sprout {
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namespace detail {
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template<typename RandomAccessIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<RandomAccessIterator>::value_type
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dft_element_gen_impl_ra(
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RandomAccessIterator const& first, RandomAccessIterator const& last,
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typename std::iterator_traits<RandomAccessIterator>::value_type::value_type arg,
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typename std::iterator_traits<RandomAccessIterator>::difference_type pivot,
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typename std::iterator_traits<RandomAccessIterator>::difference_type k = 0
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)
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{
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typedef typename std::iterator_traits<RandomAccessIterator>::value_type value_type;
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using sprout::cos;
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using sprout::sin;
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return pivot == 0 ? *first * value_type(cos(arg * k), sin(arg * k))
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: sprout::detail::dft_element_gen_impl_ra(
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first, sprout::next(first, pivot), arg, pivot / 2, k
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)
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+ sprout::detail::dft_element_gen_impl_ra(
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sprout::next(first, pivot), last, arg, (sprout::distance(first, last) - pivot) / 2, k + pivot
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)
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;
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}
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template<typename RandomAccessIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<RandomAccessIterator>::value_type
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dft_element_gen_impl(
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RandomAccessIterator const& first, RandomAccessIterator const& last,
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typename std::iterator_traits<RandomAccessIterator>::value_type::value_type arg,
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std::random_access_iterator_tag*
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)
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{
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typedef typename std::iterator_traits<RandomAccessIterator>::value_type value_type;
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return first == last ? value_type()
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: sprout::detail::dft_element_gen_impl_ra(first, last, arg, sprout::distance(first, last) / 2)
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;
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}
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::value_type
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dft_element_gen_impl_1(
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InputIterator const& first, InputIterator const& last,
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typename std::iterator_traits<InputIterator>::value_type::value_type arg,
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typename std::iterator_traits<InputIterator>::difference_type k = 0,
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typename std::iterator_traits<InputIterator>::value_type value
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= typename std::iterator_traits<InputIterator>::value_type(),
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typename std::iterator_traits<InputIterator>::value_type::value_type theta
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= typename std::iterator_traits<InputIterator>::value_type::value_type()
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)
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{
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typedef typename std::iterator_traits<InputIterator>::value_type value_type;
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using sprout::cos;
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using sprout::sin;
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return first == last ? value
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: value + sprout::detail::dft_element_gen_impl_1(
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sprout::next(first), last,
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arg,
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k + 1,
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*first * value_type(cos(theta), sin(theta)),
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arg * (k + 1)
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)
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;
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}
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::value_type
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dft_element_gen_impl(
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InputIterator const& first, InputIterator const& last,
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typename std::iterator_traits<InputIterator>::value_type::value_type arg,
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std::input_iterator_tag*
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)
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{
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return sprout::detail::dft_element_gen_impl_1(first, last, arg);
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}
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template<typename InputIterator>
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inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::value_type
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dft_element_gen(
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InputIterator const& first, InputIterator const& last,
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typename std::iterator_traits<InputIterator>::value_type::value_type arg
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)
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{
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typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
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return sprout::detail::dft_element_gen_impl(first, last, arg, category());
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}
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} // namespace detail
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} // namespace sprout
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#endif // #ifndef SPROUT_NUMERIC_DFT_DETAIL_DFT_ELEMENT_GEN_HPP
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