householder_qr.hpp

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//
// Copyright (c) 2021-2023, University of Colorado Denver. All rights reserved.
//
// This file is part of <T>LAPACK.
// <T>LAPACK is free software: you can redistribute it and/or modify it under
// the terms of the BSD 3-Clause license. See the accompanying LICENSE file.
 
#ifndef TLAPACK_HOUSEHOLDER_QR_HH
#define TLAPACK_HOUSEHOLDER_QR_HH
 
#include "tlapack/base/utils.hpp"
#include "tlapack/lapack/geqr2.hpp"
#include "tlapack/lapack/geqrf.hpp"
 
namespace tlapack {
 
enum class HouseholderQRVariant : char { Level2 = '2', Blocked = 'B' };
 
struct HouseholderQROpts : public GeqrfOpts {
    HouseholderQRVariant variant = HouseholderQRVariant::Blocked;
};
 
template <class T, TLAPACK_MATRIX matrix_t, TLAPACK_VECTOR vector_t>
constexpr WorkInfo householder_qr_worksize(const matrix_t& A,
                                           const vector_t& tau,
                                           const HouseholderQROpts& opts = {})
{
    // Call variant
    if (opts.variant == HouseholderQRVariant::Level2)
        return geqr2_worksize<T>(A, tau);
    else
        return geqrf_worksize<T>(A, tau, opts);
}
 
template <TLAPACK_MATRIX matrix_t,
          TLAPACK_VECTOR vector_t,
          TLAPACK_WORKSPACE workspace_t>
int householder_qr_work(matrix_t& A,
                        vector_t& tau,
                        workspace_t& work,
                        const HouseholderQROpts& opts = {})
{
    // Call variant
    if (opts.variant == HouseholderQRVariant::Level2)
        return geqr2_work(A, tau, work);
    else
        return geqrf_work(A, tau, work, opts);
}
 
template <TLAPACK_MATRIX matrix_t, TLAPACK_VECTOR vector_t>
int householder_qr(matrix_t& A,
                   vector_t& tau,
                   const HouseholderQROpts& opts = {})
{
    // Call variant
    if (opts.variant == HouseholderQRVariant::Level2)
        return geqr2(A, tau);
    else
        return geqrf(A, tau, opts);
}
 
}  // namespace tlapack
 
#endif  // TLAPACK_HOUSEHOLDER_QR_HH