ungqr_batch.hpp

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// Copyright (c) 2026--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 "./ungqr.hpp"
#include "../blas/tools.hpp"
#include "../macros.hpp"
 
#include <type_traits>
#include <utility>
 
namespace nda::lapack {

  template <BlasArrayCplx<3> A, BlasArrayFor<A, 2> TAU, BlasArrayFor<A, 1> W = vector_value_t<A>>
    requires(has_F_layout<A, TAU>)
  int ungqr_batch(A &&a, TAU &&tau, W &&work = vector_value_t<A>{}) { // NOLINT (temporary views are allowed here)
    auto const n_b = a.extent(2);
    auto const k   = tau.extent(0);
    EXPECTS(tau.extent(1) == n_b);
    EXPECTS(k <= a.extent(0) && k <= a.extent(1));
 
    // arrays/views must be LAPACK compatible
    EXPECTS(a.indexmap().min_stride() == 1);
    EXPECTS(tau.indexmap().min_stride() == 1);
 
    int info = 0;
    for (int i = 0; i < n_b; ++i) {
      int local_info = ungqr(a(range::all, range(k), i), tau(range::all, i), work);
      if (local_info != 0 && info == 0) info = local_info;
    }
    return info;
  }

  template <BlasArrayCplx<3> A, BlasArrayFor<A, 2> TAU, BlasArrayFor<A, 1> W = vector_value_t<A>>
    requires(has_F_layout<A, TAU>)
  int ungqr(A &&a, TAU &&tau, W &&work = vector_value_t<A>{}) { // NOLINT (temporary views are allowed here)
    return ungqr_batch(std::forward<A>(a), std::forward<TAU>(tau), std::forward<W>(work));
  }
 
} // namespace nda::lapack