inner_product.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2019 Tobias Hienzsch
#ifndef TETL_NUMERIC_INNER_PRODUCT_HPP
#define TETL_NUMERIC_INNER_PRODUCT_HPP
 
#include <etl/_utility/move.hpp>
 
namespace etl {
 
/// \brief Computes inner product (i.e. sum of products) or performs ordered
/// map/reduce operation on the range [first1, last1) and the range beginning at
/// first2.
/// \ingroup numeric
template <typename InputIt1, typename InputIt2, typename T>
[[nodiscard]] constexpr auto inner_product(InputIt1 first1, InputIt1 last1, InputIt2 first2, T init) -> T
{
    for (; first1 != last1; ++first1, ++first2) {
        init = etl::move(init) + *first1 * *first2;
    }
    return init;
}
 
/// \ingroup numeric
template <typename InputIt1, typename InputIt2, typename T, typename BinaryOperation1, typename BinaryOperation2>
[[nodiscard]] constexpr auto
inner_product(InputIt1 first1, InputIt1 last1, InputIt2 first2, T init, BinaryOperation1 op1, BinaryOperation2 op2) -> T
{
    for (; first1 != last1; ++first1, ++first2) {
        init = op1(etl::move(init), op2(*first1, *first2));
    }
    return init;
}
 
} // namespace etl
 
#endif // TETL_NUMERIC_INNER_PRODUCT_HPP