geev.hpp

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// Copyright (c) 2024--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_array.hpp"
#include "../basic_functions.hpp"
#include "../concepts.hpp"
#include "../declarations.hpp"
#include "../macros.hpp"
#include "../mem/address_space.hpp"
#include "../traits.hpp"
 
#include <cmath>
#include <complex>
#include <concepts>
 
namespace nda::lapack {

  template <MemoryMatrix A, MemoryVector WR, MemoryVector WI, MemoryMatrix VL, MemoryMatrix VR>
    requires(mem::have_host_compatible_addr_space<A, WR, WI, VL, VR> and std::same_as<double, get_value_t<A>>
             and have_same_value_type_v<A, WR, WI, VL, VR>)
  int geev(A &&a, WR &&wr, WI &&wi, VL &&vl, VR &&vr, char jobvl = 'N', char jobvr = 'V') { // NOLINT (temporary views are allowed here)
    static_assert(has_F_layout<A>, "Error in nda::lapack::geev: A must have Fortran layout");
    static_assert(has_F_layout<VL>, "Error in nda::lapack::geev: VL must have Fortran layout");
    static_assert(has_F_layout<VR>, "Error in nda::lapack::geev: VR must have Fortran layout");
 
    // check the dimensions of the input/output arrays/views
    auto const [m, n] = a.shape();
    EXPECTS(m == n);
    resize_or_check_if_view(wr, {n});
    resize_or_check_if_view(wi, {n});
 
    // check parameters
    EXPECTS(jobvl == 'V' or jobvl == 'N');
    EXPECTS(jobvr == 'V' or jobvr == 'N');
 
    // resize eigenvector matrices if needed
    int ldvl = 1;
    int ldvr = 1;
    if (jobvl == 'V') {
      resize_or_check_if_view(vl, {n, n});
      ldvl = get_ld(vl);
    }
    if (jobvr == 'V') {
      resize_or_check_if_view(vr, {n, n});
      ldvr = get_ld(vr);
    }
 
    // arrays/views must be LAPACK compatible
    EXPECTS(a.indexmap().min_stride() == 1);
    EXPECTS(wr.indexmap().min_stride() == 1);
    EXPECTS(wi.indexmap().min_stride() == 1);
    EXPECTS(jobvl == 'N' or vl.indexmap().min_stride() == 1);
    EXPECTS(jobvr == 'N' or vr.indexmap().min_stride() == 1);
 
    // first call to get the optimal buffer size
    double tmp_lwork{};
    int info = 0;
    lapack::f77::geev(jobvl, jobvr, n, a.data(), get_ld(a), wr.data(), wi.data(), vl.data(), ldvl, vr.data(), ldvr, &tmp_lwork, -1, info);
    int lwork = static_cast<int>(std::ceil(tmp_lwork));
 
    // allocate work buffer and perform actual library call
    array<double, 1> work(lwork);
    lapack::f77::geev(jobvl, jobvr, n, a.data(), get_ld(a), wr.data(), wi.data(), vl.data(), ldvl, vr.data(), ldvr, work.data(), lwork, info);
 
    return info;
  }

  template <MemoryMatrix A, MemoryVector W, MemoryMatrix VL, MemoryMatrix VR>
    requires(mem::have_host_compatible_addr_space<A, W, VL, VR> and std::same_as<std::complex<double>, get_value_t<A>>
             and have_same_value_type_v<A, W, VL, VR>)
  int geev(A &&a, W &&w, VL &&vl, VR &&vr, char jobvl = 'N', char jobvr = 'V') { // NOLINT (temporary views are allowed here)
    static_assert(has_F_layout<A>, "Error in nda::lapack::geev: A must have Fortran layout");
    static_assert(has_F_layout<VL>, "Error in nda::lapack::geev: VL must have Fortran layout");
    static_assert(has_F_layout<VR>, "Error in nda::lapack::geev: VR must have Fortran layout");
 
    // check the dimensions of the input/output arrays/views
    auto const [m, n] = a.shape();
    EXPECTS(m == n);
    resize_or_check_if_view(w, {n});
 
    // check parameters
    EXPECTS(jobvl == 'V' or jobvl == 'N');
    EXPECTS(jobvr == 'V' or jobvr == 'N');
 
    // resize eigenvector matrices if needed
    int ldvl = 1;
    int ldvr = 1;
    if (jobvl == 'V') {
      resize_or_check_if_view(vl, {n, n});
      ldvl = get_ld(vl);
    }
    if (jobvr == 'V') {
      resize_or_check_if_view(vr, {n, n});
      ldvr = get_ld(vr);
    }
 
    // arrays/views must be LAPACK compatible
    EXPECTS(a.indexmap().min_stride() == 1);
    EXPECTS(w.indexmap().min_stride() == 1);
    EXPECTS(jobvl == 'N' or vl.indexmap().min_stride() == 1);
    EXPECTS(jobvr == 'N' or vr.indexmap().min_stride() == 1);
 
    // first call to get the optimal buffer size
    array<double, 1> rwork(2 * n);
    std::complex<double> tmp_lwork{};
    int info = 0;
    lapack::f77::geev(jobvl, jobvr, n, a.data(), get_ld(a), w.data(), vl.data(), ldvl, vr.data(), ldvr, &tmp_lwork, -1, rwork.data(), info);
    int lwork = static_cast<int>(std::ceil(std::real(tmp_lwork)));
 
    // allocate work buffer and perform actual library call
    array<std::complex<double>, 1> work(lwork);
    lapack::f77::geev(jobvl, jobvr, n, a.data(), get_ld(a), w.data(), vl.data(), ldvl, vr.data(), ldvr, work.data(), lwork, rwork.data(), info);
 
    return info;
  }
 
} // namespace nda::lapack