// SPDX-License-Identifier: Apache-2.0
// 
// Copyright 2008-2016 Conrad Sanderson (https://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
// https://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 glue_trapz
//! @{



template<typename T1, typename T2>
inline
void
glue_trapz::apply(Mat<typename T1::elem_type>& out, const Glue<T1,T2,glue_trapz>& in)
  {
  arma_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const uword dim = in.aux_uword;
  
  const quasi_unwrap<T1> UX(in.A);
  const quasi_unwrap<T2> UY(in.B);
  
  if( UX.is_alias(out) || UY.is_alias(out) )
    {
    Mat<eT> tmp;
    
    glue_trapz::apply_noalias(tmp, UX.M, UY.M, dim);
    
    out.steal_mem(tmp);
    }
  else
    {
    glue_trapz::apply_noalias(out, UX.M, UY.M, dim);
    }
  }



template<typename eT>
inline
void
glue_trapz::apply_noalias(Mat<eT>& out, const Mat<eT>& X, const Mat<eT>& Y, const uword dim)
  {
  arma_debug_sigprint();
  
  arma_conform_check( (dim > 1), "trapz(): argument 'dim' must be 0 or 1" );
  
  arma_conform_check( ((X.is_vec() == false) && (X.is_empty() == false)), "trapz(): argument 'X' must be a vector" );
  
  const uword N = X.n_elem;
  
  if(dim == 0)
    {
    arma_conform_check( (N != Y.n_rows), "trapz(): length of X must equal the number of rows in Y when dim=0" );
    }
  else
  if(dim == 1)
    {
    arma_conform_check( (N != Y.n_cols), "trapz(): length of X must equal the number of columns in Y when dim=1" );
    }
  
  if(N <= 1)
    {
         if(dim == 0)  { out.zeros(1, Y.n_cols); }
    else if(dim == 1)  { out.zeros(Y.n_rows, 1); }
    
    return;
    }
  
  const Col<eT> vec_X( const_cast<eT*>(X.memptr()), X.n_elem, false, true );
  
  const Col<eT> diff_X = diff(vec_X);
  
  if(dim == 0)
    {
    const Row<eT> diff_X_t( const_cast<eT*>(diff_X.memptr()), diff_X.n_elem, false, true );
    
    out = diff_X_t * (0.5 * (Y.rows(0, N-2) + Y.rows(1, N-1)));
    }
  else
  if(dim == 1)
    {
    out = (0.5 * (Y.cols(0, N-2) + Y.cols(1, N-1))) * diff_X;
    }
  }



template<typename T1>
inline
void
op_trapz::apply(Mat<typename T1::elem_type>& out, const Op<T1,op_trapz>& in)
  {
  arma_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const uword dim = in.aux_uword_a;
  
  const quasi_unwrap<T1> UY(in.m);
  
  if(UY.is_alias(out))
    {
    Mat<eT> tmp;
    
    op_trapz::apply_noalias(tmp, UY.M, dim);
    
    out.steal_mem(tmp);
    }
  else
    {
    op_trapz::apply_noalias(out, UY.M, dim);
    }
  }



template<typename eT>
inline
void
op_trapz::apply_noalias(Mat<eT>& out, const Mat<eT>& Y, const uword dim)
  {
  arma_debug_sigprint();
  
  arma_conform_check( (dim > 1), "trapz(): argument 'dim' must be 0 or 1" );
  
  uword N = 0;
  
       if(dim == 0)  { N = Y.n_rows; }
  else if(dim == 1)  { N = Y.n_cols; }
  
  if(N <= 1)
    {
         if(dim == 0)  { out.zeros(1, Y.n_cols); }
    else if(dim == 1)  { out.zeros(Y.n_rows, 1); }
    
    return;
    }
  
  if(dim == 0)
    {
    out = sum( (0.5 * (Y.rows(0, N-2) + Y.rows(1, N-1))), 0 );
    }
  else
  if(dim == 1)
    {
    out = sum( (0.5 * (Y.cols(0, N-2) + Y.cols(1, N-1))), 1 );
    }
  }



//! @}
