// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------

//! \addtogroup op_chol
//! @{

template <typename T1>
inline void op_chol::apply(Mat<typename T1::elem_type>& out, const Op<T1, op_chol>& X) {
  arma_debug_sigprint();

  const bool status = op_chol::apply_direct(out, X.m, X.aux_uword_a);

  if (status == false) {
    out.soft_reset();
    arma_stop_runtime_error("chol(): decomposition failed");
  }
}

template <typename T1>
inline bool op_chol::apply_direct(Mat<typename T1::elem_type>& out,
                                  const Base<typename T1::elem_type, T1>& A_expr,
                                  const uword layout) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  out = A_expr.get_ref();

  arma_conform_check((out.is_square() == false),
                     "chol(): given matrix must be square sized",
                     [&]() { out.soft_reset(); });

  if (out.is_empty()) {
    return true;
  }

  if ((arma_config::check_conform) && (auxlib::rudimentary_sym_check(out) == false)) {
    if (is_cx<eT>::no) {
      arma_warn(1, "chol(): given matrix is not symmetric");
    }
    if (is_cx<eT>::yes) {
      arma_warn(1, "chol(): given matrix is not hermitian");
    }
  }

  uword KD = 0;

  const bool is_band =
      arma_config::optimise_band &&
      ((auxlib::crippled_lapack(out))
           ? false
           : ((layout == 0) ? band_helper::is_band_upper(KD, out, uword(32))
                            : band_helper::is_band_lower(KD, out, uword(32))));

  const bool status =
      (is_band) ? auxlib::chol_band(out, KD, layout) : auxlib::chol(out, layout);

  return status;
}

//! @}
