gemv.hpp

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// Copyright (c) 2019--present, The Simons Foundation
// This file is part of TRIQS/nda and is licensed under the Apache License, Version 2.0.
// SPDX-License-Identifier: Apache-2.0
// See LICENSE in the root of this distribution for details.

 
#pragma once
 
#include "./interface/cxx_interface.hpp"
#include "./tools.hpp"
#include "../concepts.hpp"
#include "../device.hpp"
#include "../macros.hpp"
#include "../mem/address_space.hpp"
#include "../traits.hpp"
 
#include <utility>
 
namespace nda::blas {


  template <BlasArrayOrConj<2> A, BlasArrayFor<A, 1> X, BlasArrayFor<A, 1> Y>
  void gemv(get_value_t<A> alpha, A const &a, X const &x, get_value_t<A> beta, Y &&y) { // NOLINT (temporary views are allowed here)
    // get the underlying matrix in case it is given as a conjugate expression
    auto &mat = get_array(a);
 
    // check the dimensions of the input/output arrays/views
    auto [m, n] = mat.shape();
    EXPECTS(m == y.size());
    EXPECTS(n == x.size());
 
    // arrays/views must be BLAS compatible
    EXPECTS(mat.indexmap().min_stride() == 1);
 
    // swap axis for the transpose case
    if constexpr (has_C_layout<A>) std::swap(m, n);
 
    // perform actual library call
    if constexpr (mem::have_device_compatible_addr_space<A, X, Y>) {
      device::gemv(get_op<A>, m, n, alpha, mat.data(), get_ld(mat), x.data(), x.indexmap().strides()[0], beta, y.data(), y.indexmap().strides()[0]);
    } else {
      f77::gemv(get_op<A>, m, n, alpha, mat.data(), get_ld(mat), x.data(), x.indexmap().strides()[0], beta, y.data(), y.indexmap().strides()[0]);
    }
  }

 
} // namespace nda::blas