// 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_sp_mean
//! @{

//! Class for finding mean values of a sparse matrix
class op_sp_mean : public traits_op_xvec {
 public:
  // Apply mean into an output sparse matrix (or vector).
  template <typename T1>
  inline static void apply(
      Mat<typename T1::elem_type>& out,
      const mtSpReduceOp<typename T1::elem_type, T1, op_sp_mean>& in);

  template <typename T1>
  inline static void apply_fast(Mat<typename T1::elem_type>& out, const SpProxy<T1>& p,
                                const uword dim);

  template <typename T1>
  inline static void apply_slow(Mat<typename T1::elem_type>& out, const SpProxy<T1>& p,
                                const uword dim);

  // Take direct mean of a set of values.  Length of array and number of values can be
  // different.
  template <typename eT>
  inline static eT direct_mean(const eT* const X, const uword length, const uword N);

  template <typename eT>
  inline static eT direct_mean_robust(const eT* const X, const uword length,
                                      const uword N);

  template <typename T1>
  inline static typename T1::elem_type mean_all(
      const SpBase<typename T1::elem_type, T1>& X);

  template <typename T1, typename spop_type>
  inline static typename T1::elem_type mean_all(const SpOp<T1, spop_type>& expr);

  // Take the mean using an iterator.
  template <typename T1, typename eT>
  inline static eT iterator_mean(T1& it, const T1& end, const uword n_zero,
                                 const eT junk);

  template <typename T1, typename eT>
  inline static eT iterator_mean_robust(T1& it, const T1& end, const uword n_zero,
                                        const eT junk);
};

//! @}
