// 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_stddev
//! @{



template<typename T1>
inline
void
op_stddev::apply(Mat<typename T1::pod_type>& out, const mtOp<typename T1::pod_type, T1, op_stddev>& in)
  {
  arma_debug_sigprint();
  
  typedef typename T1::pod_type out_eT;
  
  const uword norm_type = in.aux_uword_a;
  const uword dim       = in.aux_uword_b;
  
  arma_conform_check( (norm_type > 1), "stddev(): parameter 'norm_type' must be 0 or 1" );
  arma_conform_check( (dim > 1),       "stddev(): parameter 'dim' must be 0 or 1"       );
  
  const quasi_unwrap<T1> U(in.m);
  
  if(U.is_alias(out))
    {
    Mat<out_eT> tmp;
    
    op_stddev::apply_noalias(tmp, U.M, norm_type, dim);
    
    out.steal_mem(tmp);
    }
  else
    {
    op_stddev::apply_noalias(out, U.M, norm_type, dim);
    }
  }



template<typename in_eT>
inline
void
op_stddev::apply_noalias(Mat<typename get_pod_type<in_eT>::result>& out, const Mat<in_eT>& X, const uword norm_type, const uword dim)
  {
  arma_debug_sigprint();
  
  typedef typename get_pod_type<in_eT>::result out_eT;
  
  const uword X_n_rows = X.n_rows;
  const uword X_n_cols = X.n_cols;
  
  if(dim == 0)
    {
    arma_debug_print("op_stddev::apply_noalias(): dim = 0");
    
    out.set_size((X_n_rows > 0) ? 1 : 0, X_n_cols);
    
    if(X_n_rows > 0)
      {
      out_eT* out_mem = out.memptr();
      
      for(uword col=0; col<X_n_cols; ++col)
        {
        out_mem[col] = std::sqrt( op_var::direct_var( X.colptr(col), X_n_rows, norm_type ) );
        }
      }
    }
  else
  if(dim == 1)
    {
    arma_debug_print("op_stddev::apply_noalias(): dim = 1");
    
    out.set_size(X_n_rows, (X_n_cols > 0) ? 1 : 0);
    
    if(X_n_cols > 0)
      {
      podarray<in_eT> dat(X_n_cols);
      
      in_eT*  dat_mem = dat.memptr();
      out_eT* out_mem = out.memptr();
      
      for(uword row=0; row<X_n_rows; ++row)
        {
        dat.copy_row(X, row);
        
        out_mem[row] = std::sqrt( op_var::direct_var( dat_mem, X_n_cols, norm_type) );
        }
      }
    }
  }



template<typename T1>
inline
typename T1::pod_type
op_stddev::stddev_vec(const Base<typename T1::elem_type, T1>& X, const uword norm_type)
  {
  arma_debug_sigprint();
  
  typedef typename T1::pod_type T;
  
  arma_conform_check( (norm_type > 1), "stddev(): parameter 'norm_type' must be 0 or 1" );
  
  const quasi_unwrap<T1> U(X.get_ref());
  
  if(U.M.n_elem == 0)
    {
    arma_conform_check(true, "stddev(): object has no elements");
    
    return Datum<T>::nan;
    }
  
  return std::sqrt( op_var::direct_var(U.M.memptr(), U.M.n_elem, norm_type) );
  }



template<typename eT>
inline
typename get_pod_type<eT>::result
op_stddev::stddev_vec(const subview_col<eT>& X, const uword norm_type)
  {
  arma_debug_sigprint();
  
  typedef typename get_pod_type<eT>::result T;
  
  arma_conform_check( (norm_type > 1), "stddev(): parameter 'norm_type' must be 0 or 1" );
  
  if(X.n_elem == 0)
    {
    arma_conform_check(true, "stddev(): object has no elements");
    
    return Datum<T>::nan;
    }
  
  return std::sqrt( op_var::direct_var(X.colptr(0), X.n_rows, norm_type) );
  }




template<typename eT>
inline
typename get_pod_type<eT>::result
op_stddev::stddev_vec(const subview_row<eT>& X, const uword norm_type)
  {
  arma_debug_sigprint();
  
  typedef typename get_pod_type<eT>::result T;
  
  arma_conform_check( (norm_type > 1), "stddev(): parameter 'norm_type' must be 0 or 1" );
  
  if(X.n_elem == 0)
    {
    arma_conform_check(true, "stddev(): object has no elements");
    
    return Datum<T>::nan;
    }
  
  const Mat<eT>& A = X.m;
  
  const uword start_row = X.aux_row1;
  const uword start_col = X.aux_col1;
  
  const uword end_col_p1 = start_col + X.n_cols;
  
  podarray<eT> tmp(X.n_elem);
  eT* tmp_mem = tmp.memptr();
  
  for(uword i=0, col=start_col; col < end_col_p1; ++col, ++i)
    {
    tmp_mem[i] = A.at(start_row, col);
    }
  
  return std::sqrt( op_var::direct_var(tmp.memptr(), tmp.n_elem, norm_type) );
  }



//! @}