getrf.hpp

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// Copyright (c) 2021--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 "../basic_functions.hpp"
#include "../blas/tools.hpp"
#include "../concepts.hpp"
#include "../device.hpp"
#include "../layout_transforms.hpp"
#include "../macros.hpp"
#include "../mem/address_space.hpp"
#include "../traits.hpp"
 
#include <algorithm>
#include <type_traits>
 
namespace nda::lapack {

  template <BlasArray<2> A, PivotArrayFor<A, 1> IPIV, BlasArrayFor<A, 1> W = vector_value_t<A>>
  int getrf(A &&a, IPIV &&ipiv, [[maybe_unused]] W &&work = vector_value_t<A>{}) { // NOLINT (temporary views are allowed here)
    // for C-layout arrays/views, call getrf with the transpose
    if constexpr (has_C_layout<A>) return getrf(transpose(a), ipiv);
 
    // check the dimensions of the input/output arrays/views and resize if necessary
    auto const [m, n] = a.shape();
    resize_or_check_if_view(ipiv, {std::min(m, n)});
 
    // arrays/views must be LAPACK compatible
    EXPECTS(a.indexmap().min_stride() == 1);
    EXPECTS(ipiv.indexmap().min_stride() == 1);
 
#if defined(__has_feature)
#if __has_feature(memory_sanitizer)
    ipiv = 0;
#endif
#endif
 
    // perform actual library call
    int info = 0;
    if constexpr (mem::have_device_compatible_addr_space<A, IPIV, W>) {
      // resize/check work buffer
      int const lwork = device::getrf_buffer_size(m, n, a.data(), get_ld(a));
      resize_or_check_work_buffer(work, lwork);
 
      device::getrf(m, n, a.data(), get_ld(a), work.data(), ipiv.data(), info);
    } else {
      f77::getrf(m, n, a.data(), get_ld(a), ipiv.data(), info);
    }
    return info;
  }
 
} // namespace nda::lapack