blas2_matrix_vector_product.hpp

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// SPDX-License-Identifier: BSL-1.0
 
#ifndef TETL_LINALG_BLAS2_MATRIX_VECTOR_PRODUCT_HPP
#define TETL_LINALG_BLAS2_MATRIX_VECTOR_PRODUCT_HPP
 
#include <etl/_contracts/check.hpp>
#include <etl/_linalg/concepts.hpp>
#include <etl/_utility/cmp_less.hpp>
 
namespace etl::linalg {

template <in_matrix InMat, in_vector InVec, out_vector OutVec>
constexpr auto matrix_vector_product(InMat a, InVec x, OutVec y) noexcept -> void
{
    TETL_PRECONDITION(a.extent(1) == x.extent(0));
    TETL_PRECONDITION(a.extent(0) == y.extent(0));
 
    using size_type = detail::common_size_type_t<InMat, InVec, OutVec>;
 
    for (size_type i(0); etl::cmp_less(i, a.extent(0)); ++i) {
        y(i) = typename OutVec::element_type{};
        for (size_type j(0); etl::cmp_less(j, a.extent(1)); ++j) {
            y(i) += a(i, j) * x(j);
        }
    }
}
 
} // namespace etl::linalg
 
#endif // TETL_LINALG_BLAS2_MATRIX_VECTOR_PRODUCT_HPP