// 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 subview
//! @{


template<typename eT>
inline
subview<eT>::~subview()
  {
  arma_extra_debug_sigprint_this(this);
  }



template<typename eT>
inline
subview<eT>::subview(const Mat<eT>& in_m, const uword in_row1, const uword in_col1, const uword in_n_rows, const uword in_n_cols)
  : m       (in_m     )
  , aux_row1(in_row1  )
  , aux_col1(in_col1  )
  , n_rows  (in_n_rows)
  , n_cols  (in_n_cols)
  , n_elem  (in_n_rows*in_n_cols)
  {
  arma_extra_debug_sigprint_this(this);
  }



template<typename eT>
inline
subview<eT>::subview(const subview<eT>& in)
  : m       (in.m       )
  , aux_row1(in.aux_row1)
  , aux_col1(in.aux_col1)
  , n_rows  (in.n_rows  )
  , n_cols  (in.n_cols  )
  , n_elem  (in.n_elem  )
  {
  arma_extra_debug_sigprint(arma_str::format("this = %x   in = %x") % this % &in);
  }



template<typename eT>
inline
subview<eT>::subview(subview<eT>&& in)
  : m       (in.m       )
  , aux_row1(in.aux_row1)
  , aux_col1(in.aux_col1)
  , n_rows  (in.n_rows  )
  , n_cols  (in.n_cols  )
  , n_elem  (in.n_elem  )
  {
  arma_extra_debug_sigprint(arma_str::format("this = %x   in = %x") % this % &in);
  
  // for paranoia
  
  access::rw(in.aux_row1) = 0;
  access::rw(in.aux_col1) = 0;
  access::rw(in.n_rows  ) = 0;
  access::rw(in.n_cols  ) = 0;
  access::rw(in.n_elem  ) = 0;
  }



template<typename eT>
template<typename op_type>
inline
void
subview<eT>::inplace_op(const eT val)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>& s = *this;
  
  const uword s_n_rows = s.n_rows;
  const uword s_n_cols = s.n_cols;
  
  if(s_n_rows == 1)
    {
    Mat<eT>& A = const_cast< Mat<eT>& >(s.m);
    
    const uword A_n_rows = A.n_rows;
    
    eT* Aptr = &(A.at(s.aux_row1,s.aux_col1));
    
    uword jj;
    for(jj=1; jj < s_n_cols; jj+=2)
      {
      if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += val; Aptr += A_n_rows;  (*Aptr) += val; Aptr += A_n_rows; }
      if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= val; Aptr += A_n_rows;  (*Aptr) -= val; Aptr += A_n_rows; }
      if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= val; Aptr += A_n_rows;  (*Aptr) *= val; Aptr += A_n_rows; }
      if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= val; Aptr += A_n_rows;  (*Aptr) /= val; Aptr += A_n_rows; }
      }
    
    if((jj-1) < s_n_cols)
      {
      if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += val; }
      if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= val; }
      if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= val; }
      if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= val; }
      }
    }
  else
    {
    for(uword ucol=0; ucol < s_n_cols; ++ucol)
      {
      if(is_same_type<op_type, op_internal_plus >::yes)  { arrayops::inplace_plus ( colptr(ucol), val, s_n_rows ); }
      if(is_same_type<op_type, op_internal_minus>::yes)  { arrayops::inplace_minus( colptr(ucol), val, s_n_rows ); }
      if(is_same_type<op_type, op_internal_schur>::yes)  { arrayops::inplace_mul  ( colptr(ucol), val, s_n_rows ); }
      if(is_same_type<op_type, op_internal_div  >::yes)  { arrayops::inplace_div  ( colptr(ucol), val, s_n_rows ); }
      }
    }
  }



template<typename eT>
template<typename op_type, typename T1>
inline
void
subview<eT>::inplace_op(const Base<eT,T1>& in, const char* identifier)
  {
  arma_extra_debug_sigprint();
  
  const Proxy<T1> P(in.get_ref());
  
  subview<eT>& s = *this;
  
  const uword s_n_rows = s.n_rows;
  const uword s_n_cols = s.n_cols;
  
  arma_debug_assert_same_size(s, P, identifier);
  
  const bool use_mp      = arma_config::openmp && Proxy<T1>::use_mp && mp_gate<eT>::eval(s.n_elem);
  const bool has_overlap = P.has_overlap(s);
  
  if(has_overlap)  { arma_extra_debug_print("aliasing or overlap detected"); }
  
  if( (is_Mat<typename Proxy<T1>::stored_type>::value) || (use_mp) || (has_overlap) )
    {
    const unwrap_check<typename Proxy<T1>::stored_type> tmp(P.Q, has_overlap);
    const Mat<eT>& B = tmp.M;
    
    if(s_n_rows == 1)
      {
      Mat<eT>& A = const_cast< Mat<eT>& >(m);
      
      const uword A_n_rows = A.n_rows;
      
            eT* Aptr = &(A.at(aux_row1,aux_col1));
      const eT* Bptr = B.memptr();
      
      uword jj;
      for(jj=1; jj < s_n_cols; jj+=2)
        {
        const eT tmp1 = (*Bptr);  Bptr++;
        const eT tmp2 = (*Bptr);  Bptr++;
        
        if(is_same_type<op_type, op_internal_equ  >::yes)  { (*Aptr) =  tmp1; Aptr += A_n_rows;  (*Aptr) =  tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += tmp1; Aptr += A_n_rows;  (*Aptr) += tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= tmp1; Aptr += A_n_rows;  (*Aptr) -= tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= tmp1; Aptr += A_n_rows;  (*Aptr) *= tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= tmp1; Aptr += A_n_rows;  (*Aptr) /= tmp2; Aptr += A_n_rows; }
        }
      
      if((jj-1) < s_n_cols)
        {
        if(is_same_type<op_type, op_internal_equ  >::yes)  { (*Aptr) =  (*Bptr); }
        if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += (*Bptr); }
        if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= (*Bptr); }
        if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= (*Bptr); }
        if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= (*Bptr); }
        }
      }
    else  // not a row vector
      {
      if( (is_same_type<op_type, op_internal_equ>::yes) && (s.aux_row1 == 0) && (s_n_rows == s.m.n_rows) )
        {
        arrayops::copy( s.colptr(0), B.memptr(), s.n_elem );
        }
      else
        {
        for(uword ucol=0; ucol < s_n_cols; ++ucol)
          {
          if(is_same_type<op_type, op_internal_equ  >::yes)  { arrayops::copy         ( s.colptr(ucol), B.colptr(ucol), s_n_rows ); }
          if(is_same_type<op_type, op_internal_plus >::yes)  { arrayops::inplace_plus ( s.colptr(ucol), B.colptr(ucol), s_n_rows ); }
          if(is_same_type<op_type, op_internal_minus>::yes)  { arrayops::inplace_minus( s.colptr(ucol), B.colptr(ucol), s_n_rows ); }
          if(is_same_type<op_type, op_internal_schur>::yes)  { arrayops::inplace_mul  ( s.colptr(ucol), B.colptr(ucol), s_n_rows ); }
          if(is_same_type<op_type, op_internal_div  >::yes)  { arrayops::inplace_div  ( s.colptr(ucol), B.colptr(ucol), s_n_rows ); }
          }
        }
      }
    }
  else  // use the Proxy
    {
    if(s_n_rows == 1)
      {
      Mat<eT>& A = const_cast< Mat<eT>& >(m);
      
      const uword A_n_rows = A.n_rows;
      
      eT* Aptr = &(A.at(aux_row1,aux_col1));
      
      uword jj;
      for(jj=1; jj < s_n_cols; jj+=2)
        {
        const uword ii = (jj-1);
        
        const eT tmp1 = (Proxy<T1>::use_at) ? P.at(0,ii) : P[ii];
        const eT tmp2 = (Proxy<T1>::use_at) ? P.at(0,jj) : P[jj];
        
        if(is_same_type<op_type, op_internal_equ  >::yes)  { (*Aptr) =  tmp1; Aptr += A_n_rows;  (*Aptr) =  tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += tmp1; Aptr += A_n_rows;  (*Aptr) += tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= tmp1; Aptr += A_n_rows;  (*Aptr) -= tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= tmp1; Aptr += A_n_rows;  (*Aptr) *= tmp2; Aptr += A_n_rows; }
        if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= tmp1; Aptr += A_n_rows;  (*Aptr) /= tmp2; Aptr += A_n_rows; }
        }
      
      const uword ii = (jj-1);
      if(ii < s_n_cols)
        {
        if(is_same_type<op_type, op_internal_equ  >::yes)  { (*Aptr) =  (Proxy<T1>::use_at) ? P.at(0,ii) : P[ii]; }
        if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += (Proxy<T1>::use_at) ? P.at(0,ii) : P[ii]; }
        if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= (Proxy<T1>::use_at) ? P.at(0,ii) : P[ii]; }
        if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= (Proxy<T1>::use_at) ? P.at(0,ii) : P[ii]; }
        if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= (Proxy<T1>::use_at) ? P.at(0,ii) : P[ii]; }
        }
      }
    else  // not a row vector
      {
      if(Proxy<T1>::use_at)
        {
        for(uword ucol=0; ucol < s_n_cols; ++ucol)
          {
          eT* s_col_data = s.colptr(ucol);
          
          uword jj;
          for(jj=1; jj < s_n_rows; jj+=2)
            {
            const uword ii = (jj-1);
            
            const eT tmp1 = P.at(ii,ucol);
            const eT tmp2 = P.at(jj,ucol);
            
            if(is_same_type<op_type, op_internal_equ  >::yes)  { (*s_col_data) =  tmp1; s_col_data++;  (*s_col_data) =  tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_plus >::yes)  { (*s_col_data) += tmp1; s_col_data++;  (*s_col_data) += tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_minus>::yes)  { (*s_col_data) -= tmp1; s_col_data++;  (*s_col_data) -= tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_schur>::yes)  { (*s_col_data) *= tmp1; s_col_data++;  (*s_col_data) *= tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_div  >::yes)  { (*s_col_data) /= tmp1; s_col_data++;  (*s_col_data) /= tmp2; s_col_data++; }
            }
          
          const uword ii = (jj-1);
          if(ii < s_n_rows)
            {
            if(is_same_type<op_type, op_internal_equ  >::yes)  { (*s_col_data) =  P.at(ii,ucol); }
            if(is_same_type<op_type, op_internal_plus >::yes)  { (*s_col_data) += P.at(ii,ucol); }
            if(is_same_type<op_type, op_internal_minus>::yes)  { (*s_col_data) -= P.at(ii,ucol); }
            if(is_same_type<op_type, op_internal_schur>::yes)  { (*s_col_data) *= P.at(ii,ucol); }
            if(is_same_type<op_type, op_internal_div  >::yes)  { (*s_col_data) /= P.at(ii,ucol); }
            }
          }
        }
      else
        {
        typename Proxy<T1>::ea_type Pea = P.get_ea();
        
        uword count = 0;
        
        for(uword ucol=0; ucol < s_n_cols; ++ucol)
          {
          eT* s_col_data = s.colptr(ucol);
          
          uword jj;
          for(jj=1; jj < s_n_rows; jj+=2)
            {
            const eT tmp1 = Pea[count];  count++;
            const eT tmp2 = Pea[count];  count++;
            
            if(is_same_type<op_type, op_internal_equ  >::yes)  { (*s_col_data) =  tmp1; s_col_data++;  (*s_col_data) =  tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_plus >::yes)  { (*s_col_data) += tmp1; s_col_data++;  (*s_col_data) += tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_minus>::yes)  { (*s_col_data) -= tmp1; s_col_data++;  (*s_col_data) -= tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_schur>::yes)  { (*s_col_data) *= tmp1; s_col_data++;  (*s_col_data) *= tmp2; s_col_data++; }
            if(is_same_type<op_type, op_internal_div  >::yes)  { (*s_col_data) /= tmp1; s_col_data++;  (*s_col_data) /= tmp2; s_col_data++; }
            }
          
          if((jj-1) < s_n_rows)
            {
            if(is_same_type<op_type, op_internal_equ  >::yes)  { (*s_col_data) =  Pea[count];  count++; }
            if(is_same_type<op_type, op_internal_plus >::yes)  { (*s_col_data) += Pea[count];  count++; }
            if(is_same_type<op_type, op_internal_minus>::yes)  { (*s_col_data) -= Pea[count];  count++; }
            if(is_same_type<op_type, op_internal_schur>::yes)  { (*s_col_data) *= Pea[count];  count++; }
            if(is_same_type<op_type, op_internal_div  >::yes)  { (*s_col_data) /= Pea[count];  count++; }
            }
          }
        }
      }
    }
  }



template<typename eT>
template<typename op_type>
inline
void
subview<eT>::inplace_op(const subview<eT>& x, const char* identifier)
  {
  arma_extra_debug_sigprint();
  
  if(check_overlap(x))
    {
    const Mat<eT> tmp(x);
    
    if(is_same_type<op_type, op_internal_equ  >::yes)  { (*this).operator= (tmp); }
    if(is_same_type<op_type, op_internal_plus >::yes)  { (*this).operator+=(tmp); }
    if(is_same_type<op_type, op_internal_minus>::yes)  { (*this).operator-=(tmp); }
    if(is_same_type<op_type, op_internal_schur>::yes)  { (*this).operator%=(tmp); }
    if(is_same_type<op_type, op_internal_div  >::yes)  { (*this).operator/=(tmp); }
    
    return;
    }
  
  subview<eT>& s = *this;
  
  arma_debug_assert_same_size(s, x, identifier);
  
  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
  
  if(s_n_rows == 1)
    {
          Mat<eT>& A = const_cast< Mat<eT>& >(s.m);
    const Mat<eT>& B = x.m;
    
    const uword A_n_rows = A.n_rows;
    const uword B_n_rows = B.n_rows;
    
          eT* Aptr = &(A.at(s.aux_row1,s.aux_col1));
    const eT* Bptr = &(B.at(x.aux_row1,x.aux_col1));
    
    uword jj;
    for(jj=1; jj < s_n_cols; jj+=2)
      {
      const eT tmp1 = (*Bptr);  Bptr += B_n_rows;
      const eT tmp2 = (*Bptr);  Bptr += B_n_rows;
      
      if(is_same_type<op_type, op_internal_equ  >::yes)  { (*Aptr) =  tmp1; Aptr += A_n_rows;  (*Aptr) =  tmp2; Aptr += A_n_rows; }
      if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += tmp1; Aptr += A_n_rows;  (*Aptr) += tmp2; Aptr += A_n_rows; }
      if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= tmp1; Aptr += A_n_rows;  (*Aptr) -= tmp2; Aptr += A_n_rows; }
      if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= tmp1; Aptr += A_n_rows;  (*Aptr) *= tmp2; Aptr += A_n_rows; }
      if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= tmp1; Aptr += A_n_rows;  (*Aptr) /= tmp2; Aptr += A_n_rows; }
      }
    
    if((jj-1) < s_n_cols)
      {
      if(is_same_type<op_type, op_internal_equ  >::yes)  { (*Aptr) =  (*Bptr); }
      if(is_same_type<op_type, op_internal_plus >::yes)  { (*Aptr) += (*Bptr); }
      if(is_same_type<op_type, op_internal_minus>::yes)  { (*Aptr) -= (*Bptr); }
      if(is_same_type<op_type, op_internal_schur>::yes)  { (*Aptr) *= (*Bptr); }
      if(is_same_type<op_type, op_internal_div  >::yes)  { (*Aptr) /= (*Bptr); }
      }
    }
  else
    {
    for(uword ucol=0; ucol < s_n_cols; ++ucol)
      {
      if(is_same_type<op_type, op_internal_equ  >::yes)  { arrayops::copy         ( s.colptr(ucol), x.colptr(ucol), s_n_rows ); }
      if(is_same_type<op_type, op_internal_plus >::yes)  { arrayops::inplace_plus ( s.colptr(ucol), x.colptr(ucol), s_n_rows ); }
      if(is_same_type<op_type, op_internal_minus>::yes)  { arrayops::inplace_minus( s.colptr(ucol), x.colptr(ucol), s_n_rows ); }
      if(is_same_type<op_type, op_internal_schur>::yes)  { arrayops::inplace_mul  ( s.colptr(ucol), x.colptr(ucol), s_n_rows ); }
      if(is_same_type<op_type, op_internal_div  >::yes)  { arrayops::inplace_div  ( s.colptr(ucol), x.colptr(ucol), s_n_rows ); }
      }
    }
  }



template<typename eT>
inline
void
subview<eT>::operator= (const eT val)
  {
  arma_extra_debug_sigprint();
  
  if(n_elem != 1)
    {
    arma_debug_assert_same_size(n_rows, n_cols, 1, 1, "copy into submatrix");
    }
  
  Mat<eT>& X = const_cast< Mat<eT>& >(m);
  
  X.at(aux_row1, aux_col1) = val;
  }



template<typename eT>
inline
void
subview<eT>::operator+= (const eT val)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_plus>(val);
  }



template<typename eT>
inline
void
subview<eT>::operator-= (const eT val)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_minus>(val);
  }



template<typename eT>
inline
void
subview<eT>::operator*= (const eT val)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_schur>(val);
  }



template<typename eT>
inline
void
subview<eT>::operator/= (const eT val)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_div>(val);
  }



template<typename eT>
inline
void
subview<eT>::operator= (const subview<eT>& x)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_equ>(x, "copy into submatrix");
  }



template<typename eT>
inline
void
subview<eT>::operator+= (const subview<eT>& x)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_plus>(x, "addition");
  }



template<typename eT>
inline
void
subview<eT>::operator-= (const subview<eT>& x)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_minus>(x, "subtraction");
  }



template<typename eT>
inline
void
subview<eT>::operator%= (const subview& x)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_schur>(x, "element-wise multiplication");
  }



template<typename eT>
inline
void
subview<eT>::operator/= (const subview& x)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_div>(x, "element-wise division");
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator= (const Base<eT,T1>& in)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_equ>(in, "copy into submatrix");
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator+= (const Base<eT,T1>& in)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_plus>(in, "addition");
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator-= (const Base<eT,T1>& in)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_minus>(in, "subtraction");
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator%= (const Base<eT,T1>& in)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_schur>(in, "element-wise multiplication");
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator/= (const Base<eT,T1>& in)
  {
  arma_extra_debug_sigprint();
  
  inplace_op<op_internal_div>(in, "element-wise division");
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator=(const SpBase<eT, T1>& x)
  {
  arma_extra_debug_sigprint();
  
  const SpProxy<T1> p(x.get_ref());
  
  arma_debug_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "copy into submatrix");
  
  // Clear the subview.
  zeros();
  
  // Iterate through the sparse subview and set the nonzero values appropriately.
  typename SpProxy<T1>::const_iterator_type cit     = p.begin();
  typename SpProxy<T1>::const_iterator_type cit_end = p.end();
  
  while(cit != cit_end)
    {
    at(cit.row(), cit.col()) = *cit;
    ++cit;
    }
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator+=(const SpBase<eT, T1>& x)
  {
  arma_extra_debug_sigprint();
  
  const SpProxy<T1> p(x.get_ref());
  
  arma_debug_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "addition");
  
  // Iterate through the sparse subview and add its values.
  typename SpProxy<T1>::const_iterator_type cit     = p.begin();
  typename SpProxy<T1>::const_iterator_type cit_end = p.end();
  
  while(cit != cit_end)
    {
    at(cit.row(), cit.col()) += *cit;
    ++cit;
    }
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator-=(const SpBase<eT, T1>& x)
  {
  arma_extra_debug_sigprint();
  
  const SpProxy<T1> p(x.get_ref());
  
  arma_debug_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "subtraction");
  
  // Iterate through the sparse subview and subtract its values.
  typename SpProxy<T1>::const_iterator_type cit     = p.begin();
  typename SpProxy<T1>::const_iterator_type cit_end = p.end();
  
  while(cit != cit_end)
    {
    at(cit.row(), cit.col()) -= *cit;
    ++cit;
    }
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator%=(const SpBase<eT, T1>& x)
  {
  arma_extra_debug_sigprint();
  
  const uword s_n_rows = (*this).n_rows;
  const uword s_n_cols = (*this).n_cols;
  
  const SpProxy<T1> p(x.get_ref());
  
  arma_debug_assert_same_size(s_n_rows, s_n_cols, p.get_n_rows(), p.get_n_cols(), "element-wise multiplication");
  
  if(n_elem == 0)  { return; }
  
  if(p.get_n_nonzero() == 0)  { (*this).zeros(); return; }
  
  // Iterate over nonzero values.
  // Any zero values in the sparse expression will result in a zero in our subview.
  typename SpProxy<T1>::const_iterator_type cit     = p.begin();
  typename SpProxy<T1>::const_iterator_type cit_end = p.end();
  
  uword r = 0;
  uword c = 0;
  
  while(cit != cit_end)
    {
    const uword cit_row = cit.row();
    const uword cit_col = cit.col();
    
    while( ((r == cit_row) && (c == cit_col)) == false )
      {
      at(r,c) = eT(0);
      
      r++;  if(r >= s_n_rows)  { r = 0; c++; }
      }
    
    at(r, c) *= (*cit); 
    
    ++cit;
    r++;  if(r >= s_n_rows)  { r = 0; c++; }
    }
  }



template<typename eT>
template<typename T1>
inline
void
subview<eT>::operator/=(const SpBase<eT, T1>& x)
  {
  arma_extra_debug_sigprint();
  
  const SpProxy<T1> p(x.get_ref());
  
  arma_debug_assert_same_size(n_rows, n_cols, p.get_n_rows(), p.get_n_cols(), "element-wise division");
  
  // This is probably going to fill your subview with a bunch of NaNs,
  // so I'm not going to bother to implement it fast.
  // You can have slow NaNs.  They're fine too.
  for(uword c = 0; c < n_cols; ++c)
  for(uword r = 0; r < n_rows; ++r)
    {
    at(r, c) /= p.at(r, c);
    }
  }



template<typename eT>
template<typename T1, typename gen_type>
inline
typename enable_if2< is_same_type<typename T1::elem_type, eT>::value, void>::result
subview<eT>::operator= (const Gen<T1,gen_type>& in)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_assert_same_size(n_rows, n_cols, in.n_rows, in.n_cols, "copy into submatrix");
  
  in.apply(*this);
  }



template<typename eT>
inline
void
subview<eT>::operator=(const std::initializer_list<eT>& list)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (is_vec() == false), "copy into submatrix: size mismatch" );
  
  const uword N = uword(list.size());
  
  if(n_rows == 1)
    {
    arma_debug_assert_same_size(1, n_cols, 1, N, "copy into submatrix");
    
    auto it = list.begin();
    
    for(uword ii=0; ii < N; ++ii)  { (*this).at(0,ii) = (*it); ++it; }
    }
  else
  if(n_cols == 1)
    {
    arma_debug_assert_same_size(n_rows, 1, N, 1, "copy into submatrix");
    
    arrayops::copy( (*this).colptr(0), list.begin(), N );
    }
  }



template<typename eT>
inline
void
subview<eT>::operator=(const std::initializer_list< std::initializer_list<eT> >& list)
  {
  arma_extra_debug_sigprint();
  
  const Mat<eT> tmp(list);
  
  (*this).operator=(tmp);
  }



//! apply a functor to each element
template<typename eT>
template<typename functor>
inline
void
subview<eT>::for_each(functor F)
  {
  arma_extra_debug_sigprint();
  
  Mat<eT>& X = const_cast< Mat<eT>& >(m);
  
  if(n_rows == 1)
    {
    const uword urow          = aux_row1;
    const uword start_col     = aux_col1;
    const uword end_col_plus1 = start_col + n_cols;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
      {
      F( X.at(urow, ucol) );
      }
    }
  else
    {
    const uword start_col = aux_col1;
    const uword start_row = aux_row1;
    
    const uword end_col_plus1 = start_col + n_cols;
    const uword end_row_plus1 = start_row + n_rows;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
    for(uword urow = start_row; urow < end_row_plus1; ++urow)
      {
      F( X.at(urow, ucol) );
      }
    }
  }



template<typename eT>
template<typename functor>
inline
void
subview<eT>::for_each(functor F) const
  {
  arma_extra_debug_sigprint();
  
  const Mat<eT>& X = m;
  
  if(n_rows == 1)
    {
    const uword urow          = aux_row1;
    const uword start_col     = aux_col1;
    const uword end_col_plus1 = start_col + n_cols;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
      {
      F( X.at(urow, ucol) );
      }
    }
  else
    {
    const uword start_col = aux_col1;
    const uword start_row = aux_row1;
    
    const uword end_col_plus1 = start_col + n_cols;
    const uword end_row_plus1 = start_row + n_rows;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
    for(uword urow = start_row; urow < end_row_plus1; ++urow)
      {
      F( X.at(urow, ucol) );
      }
    }
  }



//! transform each element in the subview using a functor
template<typename eT>
template<typename functor>
inline
void
subview<eT>::transform(functor F)
  {
  arma_extra_debug_sigprint();
  
  Mat<eT>& X = const_cast< Mat<eT>& >(m);
  
  if(n_rows == 1)
    {
    const uword urow          = aux_row1;
    const uword start_col     = aux_col1;
    const uword end_col_plus1 = start_col + n_cols;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
      {
      X.at(urow, ucol) = eT( F( X.at(urow, ucol) ) );
      }
    }
  else
    {
    const uword start_col = aux_col1;
    const uword start_row = aux_row1;
    
    const uword end_col_plus1 = start_col + n_cols;
    const uword end_row_plus1 = start_row + n_rows;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
    for(uword urow = start_row; urow < end_row_plus1; ++urow)
      {
      X.at(urow, ucol) = eT( F( X.at(urow, ucol) ) );
      }
    }
  }



//! imbue (fill) the subview with values provided by a functor
template<typename eT>
template<typename functor>
inline
void
subview<eT>::imbue(functor F)
  {
  arma_extra_debug_sigprint();
  
  Mat<eT>& X = const_cast< Mat<eT>& >(m);
  
  if(n_rows == 1)
    {
    const uword urow          = aux_row1;
    const uword start_col     = aux_col1;
    const uword end_col_plus1 = start_col + n_cols;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
      {
      X.at(urow, ucol) = eT( F() );
      }
    }
  else
    {
    const uword start_col = aux_col1;
    const uword start_row = aux_row1;
    
    const uword end_col_plus1 = start_col + n_cols;
    const uword end_row_plus1 = start_row + n_rows;
    
    for(uword ucol = start_col; ucol < end_col_plus1; ++ucol)
    for(uword urow = start_row; urow < end_row_plus1; ++urow)
      {
      X.at(urow, ucol) = eT( F() );
      }
    }
  }



template<typename eT>
inline
void
subview<eT>::replace(const eT old_val, const eT new_val)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>& s = *this;
  
  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
  
  if(s_n_rows == 1)
    {
    Mat<eT>& A = const_cast< Mat<eT>& >(s.m);
    
    const uword A_n_rows = A.n_rows;
    
    eT* Aptr = &(A.at(s.aux_row1,s.aux_col1));
    
    if(arma_isnan(old_val))
      {
      for(uword ucol=0; ucol < s_n_cols; ++ucol)
        {
        (*Aptr) = (arma_isnan(*Aptr)) ? new_val : (*Aptr);
        
        Aptr += A_n_rows;
        }
      }
    else
      {
      for(uword ucol=0; ucol < s_n_cols; ++ucol)
        {
        (*Aptr) = ((*Aptr) == old_val) ? new_val : (*Aptr);
        
        Aptr += A_n_rows;
        }
      }
    }
  else
    {
    for(uword ucol=0; ucol < s_n_cols; ++ucol)
      {
      arrayops::replace(s.colptr(ucol), s_n_rows, old_val, new_val);
      }
    }
  }



template<typename eT>
inline
void
subview<eT>::clean(const typename get_pod_type<eT>::result threshold)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>& s = *this;
  
  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
  
  for(uword ucol=0; ucol < s_n_cols; ++ucol)
    {
    arrayops::clean( s.colptr(ucol), s_n_rows, threshold );
    }
  }



template<typename eT>
inline
void
subview<eT>::fill(const eT val)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>& s = *this;
  
  const uword s_n_cols = s.n_cols;
  const uword s_n_rows = s.n_rows;
  
  if(s_n_rows == 1)
    {
    Mat<eT>& A = const_cast< Mat<eT>& >(s.m);
    
    const uword A_n_rows = A.n_rows;
    
    eT* Aptr = &(A.at(s.aux_row1,s.aux_col1));
    
    uword jj;
    for(jj=1; jj < s_n_cols; jj+=2)
      {
      (*Aptr) = val;  Aptr += A_n_rows;
      (*Aptr) = val;  Aptr += A_n_rows;
      }
    
    if((jj-1) < s_n_cols)
      {
      (*Aptr) = val;
      }
    }
  else
    {
    if( (s.aux_row1 == 0) && (s_n_rows == s.m.n_rows) )
      {
      arrayops::inplace_set( s.colptr(0), val, s.n_elem );
      
      return;
      }
    
    for(uword ucol=0; ucol < s_n_cols; ++ucol)
      {
      arrayops::inplace_set( s.colptr(ucol), val, s_n_rows );
      }
    }
  }



template<typename eT>
inline
void
subview<eT>::zeros()
  {
  arma_extra_debug_sigprint();
  
  (*this).fill(eT(0));
  }



template<typename eT>
inline
void
subview<eT>::ones()
  {
  arma_extra_debug_sigprint();
  
  (*this).fill(eT(1));
  }



template<typename eT>
inline
void
subview<eT>::eye()
  {
  arma_extra_debug_sigprint();
  
  (*this).zeros();
  
  const uword N = (std::min)(n_rows, n_cols);
  
  for(uword ii=0; ii < N; ++ii)
    {
    at(ii,ii) = eT(1);
    }
  }



template<typename eT>
inline
void
subview<eT>::randu()
  {
  arma_extra_debug_sigprint();
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  if(local_n_rows == 1)
    {
    for(uword ii=0; ii < local_n_cols; ++ii)
      {
      at(0,ii) = eT(arma_rng::randu<eT>());
      }
    }
  else
    {
    for(uword ii=0; ii < local_n_cols; ++ii)
      {
      arma_rng::randu<eT>::fill( colptr(ii), local_n_rows );
      }
    }
  }



template<typename eT>
inline
void
subview<eT>::randn()
  {
  arma_extra_debug_sigprint();
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  if(local_n_rows == 1)
    {
    for(uword ii=0; ii < local_n_cols; ++ii)
      {
      at(0,ii) = eT(arma_rng::randn<eT>());
      }
    }
  else
    {
    for(uword ii=0; ii < local_n_cols; ++ii)
      {
      arma_rng::randn<eT>::fill( colptr(ii), local_n_rows );
      }
    }
  }



template<typename eT>
inline
eT
subview<eT>::at_alt(const uword ii) const
  {
  return operator[](ii);
  }



template<typename eT>
inline
eT&
subview<eT>::operator[](const uword ii)
  {
  const uword in_col = ii / n_rows;
  const uword in_row = ii % n_rows;
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return access::rw( (const_cast< Mat<eT>& >(m)).mem[index] );
  }



template<typename eT>
inline
eT
subview<eT>::operator[](const uword ii) const
  {
  const uword in_col = ii / n_rows;
  const uword in_row = ii % n_rows;
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return m.mem[index];
  }



template<typename eT>
inline
eT&
subview<eT>::operator()(const uword ii)
  {
  arma_debug_check( (ii >= n_elem), "subview::operator(): index out of bounds" );
    
  const uword in_col = ii / n_rows;
  const uword in_row = ii % n_rows;
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return access::rw( (const_cast< Mat<eT>& >(m)).mem[index] );
  }



template<typename eT>
inline
eT
subview<eT>::operator()(const uword ii) const
  {
  arma_debug_check( (ii >= n_elem), "subview::operator(): index out of bounds" );
  
  const uword in_col = ii / n_rows;
  const uword in_row = ii % n_rows;
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return m.mem[index];
  }



template<typename eT>
inline
eT&
subview<eT>::operator()(const uword in_row, const uword in_col)
  {
  arma_debug_check( ((in_row >= n_rows) || (in_col >= n_cols)), "subview::operator(): index out of bounds" );
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return access::rw( (const_cast< Mat<eT>& >(m)).mem[index] );
  }



template<typename eT>
inline
eT
subview<eT>::operator()(const uword in_row, const uword in_col) const
  {
  arma_debug_check( ((in_row >= n_rows) || (in_col >= n_cols)), "subview::operator(): index out of bounds" );
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return m.mem[index];
  }



template<typename eT>
inline
eT&
subview<eT>::at(const uword in_row, const uword in_col)
  {
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return access::rw( (const_cast< Mat<eT>& >(m)).mem[index] );
  }



template<typename eT>
inline
eT
subview<eT>::at(const uword in_row, const uword in_col) const
  {
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return m.mem[index];
  }



template<typename eT>
inline
eT&
subview<eT>::front()
  {
  const uword index = aux_col1*m.n_rows + aux_row1;
  
  return access::rw( (const_cast< Mat<eT>& >(m)).mem[index] );
  }



template<typename eT>
inline
eT
subview<eT>::front() const
  {
  const uword index = aux_col1*m.n_rows + aux_row1;
  
  return m.mem[index];
  }



template<typename eT>
inline
eT&
subview<eT>::back()
  {
  const uword in_row = n_rows - 1;
  const uword in_col = n_cols - 1;
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return access::rw( (const_cast< Mat<eT>& >(m)).mem[index] );
  }



template<typename eT>
inline
eT
subview<eT>::back() const
  {
  const uword in_row = n_rows - 1;
  const uword in_col = n_cols - 1;
  
  const uword index = (in_col + aux_col1)*m.n_rows + aux_row1 + in_row;
  
  return m.mem[index];
  }



template<typename eT>
arma_inline
eT*
subview<eT>::colptr(const uword in_col)
  {
  return & access::rw((const_cast< Mat<eT>& >(m)).mem[ (in_col + aux_col1)*m.n_rows + aux_row1 ]);
  }



template<typename eT>
arma_inline
const eT*
subview<eT>::colptr(const uword in_col) const
  {
  return & m.mem[ (in_col + aux_col1)*m.n_rows + aux_row1 ];
  }



template<typename eT>
template<typename eT2>
inline
bool
subview<eT>::check_overlap(const subview<eT2>& x) const
  {
  if(is_same_type<eT,eT2>::value == false)  { return false; }
  
  const subview<eT>& s = (*this);
  
  if(void_ptr(&(s.m)) != void_ptr(&(x.m)))  { return false; }
  
  if( (s.n_elem == 0) || (x.n_elem == 0) )  { return false; }
  
  const uword s_row_start  = s.aux_row1;
  const uword s_row_end_p1 = s_row_start + s.n_rows;
  
  const uword s_col_start  = s.aux_col1;
  const uword s_col_end_p1 = s_col_start + s.n_cols;
  
  
  const uword x_row_start  = x.aux_row1;
  const uword x_row_end_p1 = x_row_start + x.n_rows;
  
  const uword x_col_start  = x.aux_col1;
  const uword x_col_end_p1 = x_col_start + x.n_cols;
  
  
  const bool outside_rows = ( (x_row_start >= s_row_end_p1) || (s_row_start >= x_row_end_p1) );
  const bool outside_cols = ( (x_col_start >= s_col_end_p1) || (s_col_start >= x_col_end_p1) );
  
  return ( (outside_rows == false) && (outside_cols == false) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::is_vec() const
  {
  return ( (n_rows == 1) || (n_cols == 1) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::is_finite() const
  {
  arma_extra_debug_sigprint();
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  for(uword ii=0; ii<local_n_cols; ++ii)
    {
    if(arrayops::is_finite(colptr(ii), local_n_rows) == false)  { return false; }
    }
  
  return true;
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::is_zero(const typename get_pod_type<eT>::result tol) const
  {
  arma_extra_debug_sigprint();
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  for(uword ii=0; ii<local_n_cols; ++ii)
    {
    if(arrayops::is_zero(colptr(ii), local_n_rows, tol) == false)  { return false; }
    }
  
  return true;
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::has_inf() const
  {
  arma_extra_debug_sigprint();
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  for(uword ii=0; ii<local_n_cols; ++ii)
    {
    if(arrayops::has_inf(colptr(ii), local_n_rows))  { return true; }
    }
  
  return false;
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::has_nan() const
  {
  arma_extra_debug_sigprint();
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  for(uword ii=0; ii<local_n_cols; ++ii)
    {
    if(arrayops::has_nan(colptr(ii), local_n_rows))  { return true; }
    }
  
  return false;
  }



//! X = Y.submat(...)
template<typename eT>
inline
void
subview<eT>::extract(Mat<eT>& out, const subview<eT>& in)
  {
  arma_extra_debug_sigprint();
  
  // NOTE: we're assuming that the matrix has already been set to the correct size and there is no aliasing;
  // size setting and alias checking is done by either the Mat contructor or operator=()
  
  const uword n_rows = in.n_rows;  // number of rows in the subview
  const uword n_cols = in.n_cols;  // number of columns in the subview
  
  arma_extra_debug_print(arma_str::format("out.n_rows = %d   out.n_cols = %d    in.m.n_rows = %d  in.m.n_cols = %d") % out.n_rows % out.n_cols % in.m.n_rows % in.m.n_cols );
  
  
  if(in.is_vec())
    {
    if(n_cols == 1)   // a column vector
      {
      arma_extra_debug_print("subview::extract(): copying col (going across rows)");
      
      // in.colptr(0) the first column of the subview, taking into account any row offset
      arrayops::copy( out.memptr(), in.colptr(0), n_rows );
      }
    else   // a row vector (possibly empty)
      {
      arma_extra_debug_print("subview::extract(): copying row (going across columns)");
      
      eT* out_mem = out.memptr();
      
      const uword X_n_rows = in.m.n_rows;
      
      const eT* Xptr = &(in.m.at(in.aux_row1,in.aux_col1));
      
      uword j;
      
      for(j=1; j < n_cols; j+=2)
        {
        const eT tmp1 = (*Xptr);  Xptr += X_n_rows;
        const eT tmp2 = (*Xptr);  Xptr += X_n_rows;
        
        (*out_mem) = tmp1;  out_mem++;
        (*out_mem) = tmp2;  out_mem++;
        }
      
      if((j-1) < n_cols)
        {
        (*out_mem) = (*Xptr);
        }
      }
    }
  else   // general submatrix
    {
    arma_extra_debug_print("subview::extract(): general submatrix");
    
    if( (in.aux_row1 == 0) && (n_rows == in.m.n_rows) )
      {
      arrayops::copy( out.memptr(), in.colptr(0), in.n_elem );
      
      return;
      }
    
    for(uword col=0; col < n_cols; ++col)
      {
      arrayops::copy( out.colptr(col), in.colptr(col), n_rows );
      }
    }
  }



//! X += Y.submat(...)
template<typename eT>
inline
void
subview<eT>::plus_inplace(Mat<eT>& out, const subview<eT>& in)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_assert_same_size(out, in, "addition");
  
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
    
    const Mat<eT>& X = in.m;
    
    const uword row       = in.aux_row1;
    const uword start_col = in.aux_col1;
    
    uword i,j;
    for(i=0, j=1; j < n_cols; i+=2, j+=2)
      {
      const eT tmp1 = X.at(row, start_col+i);
      const eT tmp2 = X.at(row, start_col+j);
        
      out_mem[i] += tmp1;
      out_mem[j] += tmp2;
      }
    
    if(i < n_cols)
      {
      out_mem[i] += X.at(row, start_col+i);
      }
    }
  else
    {
    for(uword col=0; col < n_cols; ++col)
      {
      arrayops::inplace_plus(out.colptr(col), in.colptr(col), n_rows);
      }
    }
  }



//! X -= Y.submat(...)
template<typename eT>
inline
void
subview<eT>::minus_inplace(Mat<eT>& out, const subview<eT>& in)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_assert_same_size(out, in, "subtraction");
  
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
    
    const Mat<eT>& X = in.m;
    
    const uword row       = in.aux_row1;
    const uword start_col = in.aux_col1;
    
    uword i,j;
    for(i=0, j=1; j < n_cols; i+=2, j+=2)
      {
      const eT tmp1 = X.at(row, start_col+i);
      const eT tmp2 = X.at(row, start_col+j);
        
      out_mem[i] -= tmp1;
      out_mem[j] -= tmp2;
      }
    
    if(i < n_cols)
      {
      out_mem[i] -= X.at(row, start_col+i);
      }
    }
  else
    {
    for(uword col=0; col < n_cols; ++col)
      {
      arrayops::inplace_minus(out.colptr(col), in.colptr(col), n_rows);
      }
    }
  }



//! X %= Y.submat(...)
template<typename eT>
inline
void
subview<eT>::schur_inplace(Mat<eT>& out, const subview<eT>& in)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_assert_same_size(out, in, "element-wise multiplication");
  
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
    
    const Mat<eT>& X = in.m;
    
    const uword row       = in.aux_row1;
    const uword start_col = in.aux_col1;
    
    uword i,j;
    for(i=0, j=1; j < n_cols; i+=2, j+=2)
      {
      const eT tmp1 = X.at(row, start_col+i);
      const eT tmp2 = X.at(row, start_col+j);
        
      out_mem[i] *= tmp1;
      out_mem[j] *= tmp2;
      }
    
    if(i < n_cols)
      {
      out_mem[i] *= X.at(row, start_col+i);
      }
    }
  else
    {
    for(uword col=0; col < n_cols; ++col)
      {
      arrayops::inplace_mul(out.colptr(col), in.colptr(col), n_rows);
      }
    }
  }



//! X /= Y.submat(...)
template<typename eT>
inline
void
subview<eT>::div_inplace(Mat<eT>& out, const subview<eT>& in)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_assert_same_size(out, in, "element-wise division");
  
  const uword n_rows = in.n_rows;
  const uword n_cols = in.n_cols;
  
  if(n_rows == 1)
    {
    eT* out_mem = out.memptr();
    
    const Mat<eT>& X = in.m;
    
    const uword row       = in.aux_row1;
    const uword start_col = in.aux_col1;
    
    uword i,j;
    for(i=0, j=1; j < n_cols; i+=2, j+=2)
      {
      const eT tmp1 = X.at(row, start_col+i);
      const eT tmp2 = X.at(row, start_col+j);
        
      out_mem[i] /= tmp1;
      out_mem[j] /= tmp2;
      }
    
    if(i < n_cols)
      {
      out_mem[i] /= X.at(row, start_col+i);
      }
    }
  else
    {
    for(uword col=0; col < n_cols; ++col)
      {
      arrayops::inplace_div(out.colptr(col), in.colptr(col), n_rows);
      }
    }
  }



//! creation of subview (row vector)
template<typename eT>
inline
subview_row<eT>
subview<eT>::row(const uword row_num)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( row_num >= n_rows, "subview::row(): out of bounds" );
  
  const uword base_row = aux_row1 + row_num;
  
  return subview_row<eT>(m, base_row, aux_col1, n_cols);
  }



//! creation of subview (row vector)
template<typename eT>
inline
const subview_row<eT>
subview<eT>::row(const uword row_num) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( row_num >= n_rows, "subview::row(): out of bounds" );
  
  const uword base_row = aux_row1 + row_num;
  
  return subview_row<eT>(m, base_row, aux_col1, n_cols);
  }



template<typename eT>
inline
subview_row<eT>
subview<eT>::operator()(const uword row_num, const span& col_span)
  {
  arma_extra_debug_sigprint();
  
  const bool col_all = col_span.whole;
  
  const uword local_n_cols = n_cols;
  
  const uword in_col1       = col_all ? 0            : col_span.a;
  const uword in_col2       =                          col_span.b;
  const uword submat_n_cols = col_all ? local_n_cols : in_col2 - in_col1 + 1;
  
  const uword base_col1     = aux_col1 + in_col1;  
  const uword base_row      = aux_row1 + row_num;
  
  arma_debug_check
    (
    (row_num >= n_rows)
    ||
    ( col_all ? false : ((in_col1 > in_col2) || (in_col2 >= local_n_cols)) )
    ,
    "subview::operator(): indices out of bounds or incorrectly used"
    );
  
  return subview_row<eT>(m, base_row, base_col1, submat_n_cols);
  }



template<typename eT>
inline
const subview_row<eT>
subview<eT>::operator()(const uword row_num, const span& col_span) const
  {
  arma_extra_debug_sigprint();
  
  const bool col_all = col_span.whole;
  
  const uword local_n_cols = n_cols;
  
  const uword in_col1       = col_all ? 0            : col_span.a;
  const uword in_col2       =                          col_span.b;
  const uword submat_n_cols = col_all ? local_n_cols : in_col2 - in_col1 + 1;
  
  const uword base_col1     = aux_col1 + in_col1;
  const uword base_row      = aux_row1 + row_num;
  
  arma_debug_check
    (
    (row_num >= n_rows)
    ||
    ( col_all ? false : ((in_col1 > in_col2) || (in_col2 >= local_n_cols)) )
    ,
    "subview::operator(): indices out of bounds or incorrectly used"
    );
  
  return subview_row<eT>(m, base_row, base_col1, submat_n_cols);
  }



//! creation of subview (column vector)
template<typename eT>
inline
subview_col<eT>
subview<eT>::col(const uword col_num)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( col_num >= n_cols, "subview::col(): out of bounds" );
  
  const uword base_col = aux_col1 + col_num;
  
  return subview_col<eT>(m, base_col, aux_row1, n_rows);
  }



//! creation of subview (column vector)
template<typename eT>
inline
const subview_col<eT>
subview<eT>::col(const uword col_num) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( col_num >= n_cols, "subview::col(): out of bounds" );
  
  const uword base_col = aux_col1 + col_num;
  
  return subview_col<eT>(m, base_col, aux_row1, n_rows);
  }



template<typename eT>
inline
subview_col<eT>
subview<eT>::operator()(const span& row_span, const uword col_num)
  {
  arma_extra_debug_sigprint();
  
  const bool row_all = row_span.whole;
  
  const uword local_n_rows = n_rows;
  
  const uword in_row1       = row_all ? 0            : row_span.a;
  const uword in_row2       =                          row_span.b;
  const uword submat_n_rows = row_all ? local_n_rows : in_row2 - in_row1 + 1;
  
  const uword base_row1       = aux_row1 + in_row1;  
  const uword base_col        = aux_col1 + col_num;
  
  arma_debug_check
    (
    (col_num >= n_cols)
    ||
    ( row_all ? false : ((in_row1 > in_row2) || (in_row2 >= local_n_rows)) )
    ,
    "subview::operator(): indices out of bounds or incorrectly used"
    );
  
  return subview_col<eT>(m, base_col, base_row1, submat_n_rows);
  }



template<typename eT>
inline
const subview_col<eT>
subview<eT>::operator()(const span& row_span, const uword col_num) const
  {
  arma_extra_debug_sigprint();
  
  const bool row_all = row_span.whole;
  
  const uword local_n_rows = n_rows;
  
  const uword in_row1       = row_all ? 0            : row_span.a;
  const uword in_row2       =                          row_span.b;
  const uword submat_n_rows = row_all ? local_n_rows : in_row2 - in_row1 + 1;
  
  const uword base_row1       = aux_row1 + in_row1;
  const uword base_col        = aux_col1 + col_num;
  
  arma_debug_check
    (
    (col_num >= n_cols)
    ||
    ( row_all ? false : ((in_row1 > in_row2) || (in_row2 >= local_n_rows)) )
    ,
    "subview::operator(): indices out of bounds or incorrectly used"
    );
  
  return subview_col<eT>(m, base_col, base_row1, submat_n_rows);
  }



//! create a Col object which uses memory from an existing matrix object.
//! this approach is currently not alias safe
//! and does not take into account that the parent matrix object could be deleted.
//! if deleted memory is accessed by the created Col object,
//! it will cause memory corruption and/or a crash
template<typename eT>
inline
Col<eT>
subview<eT>::unsafe_col(const uword col_num)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( col_num >= n_cols, "subview::unsafe_col(): out of bounds" );
  
  return Col<eT>(colptr(col_num), n_rows, false, true);
  }



//! create a Col object which uses memory from an existing matrix object.
//! this approach is currently not alias safe
//! and does not take into account that the parent matrix object could be deleted.
//! if deleted memory is accessed by the created Col object,
//! it will cause memory corruption and/or a crash
template<typename eT>
inline
const Col<eT>
subview<eT>::unsafe_col(const uword col_num) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( col_num >= n_cols, "subview::unsafe_col(): out of bounds" );
  
  return Col<eT>(const_cast<eT*>(colptr(col_num)), n_rows, false, true);
  }



//! creation of subview (submatrix comprised of specified row vectors)
template<typename eT>
inline
subview<eT>
subview<eT>::rows(const uword in_row1, const uword in_row2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_row1 > in_row2) || (in_row2 >= n_rows),
    "subview::rows(): indices out of bounds or incorrectly used"
    );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  const uword base_row1 = aux_row1 + in_row1;
  
  return subview<eT>(m, base_row1, aux_col1, subview_n_rows, n_cols );
  }



//! creation of subview (submatrix comprised of specified row vectors)
template<typename eT>
inline
const subview<eT>
subview<eT>::rows(const uword in_row1, const uword in_row2) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_row1 > in_row2) || (in_row2 >= n_rows),
    "subview::rows(): indices out of bounds or incorrectly used"
    );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  const uword base_row1 = aux_row1 + in_row1;
  
  return subview<eT>(m, base_row1, aux_col1, subview_n_rows, n_cols );
  }



//! creation of subview (submatrix comprised of specified column vectors)
template<typename eT>
inline
subview<eT>
subview<eT>::cols(const uword in_col1, const uword in_col2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_col1 > in_col2) || (in_col2 >= n_cols),
    "subview::cols(): indices out of bounds or incorrectly used"
    );
  
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  const uword base_col1 = aux_col1 + in_col1;
  
  return subview<eT>(m, aux_row1, base_col1, n_rows, subview_n_cols);
  }



//! creation of subview (submatrix comprised of specified column vectors)
template<typename eT>
inline
const subview<eT>
subview<eT>::cols(const uword in_col1, const uword in_col2) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_col1 > in_col2) || (in_col2 >= n_cols),
    "subview::cols(): indices out of bounds or incorrectly used"
    );
  
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  const uword base_col1 = aux_col1 + in_col1;
  
  return subview<eT>(m, aux_row1, base_col1, n_rows, subview_n_cols);
  }



//! creation of subview (submatrix)
template<typename eT>
inline
subview<eT>
subview<eT>::submat(const uword in_row1, const uword in_col1, const uword in_row2, const uword in_col2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_row1 > in_row2) || (in_col1 >  in_col2) || (in_row2 >= n_rows) || (in_col2 >= n_cols),
    "subview::submat(): indices out of bounds or incorrectly used"
    );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  
  const uword base_row1 = aux_row1 + in_row1;
  const uword base_col1 = aux_col1 + in_col1;
  
  return subview<eT>(m, base_row1, base_col1, subview_n_rows, subview_n_cols);
  }



//! creation of subview (generic submatrix)
template<typename eT>
inline
const subview<eT>
subview<eT>::submat(const uword in_row1, const uword in_col1, const uword in_row2, const uword in_col2) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_row1 > in_row2) || (in_col1 >  in_col2) || (in_row2 >= n_rows) || (in_col2 >= n_cols),
    "subview::submat(): indices out of bounds or incorrectly used"
    );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  
  const uword base_row1 = aux_row1 + in_row1;
  const uword base_col1 = aux_col1 + in_col1;
  
  return subview<eT>(m, base_row1, base_col1, subview_n_rows, subview_n_cols);
  }



//! creation of subview (submatrix)
template<typename eT>
inline
subview<eT>
subview<eT>::submat(const span& row_span, const span& col_span)
  {
  arma_extra_debug_sigprint();
  
  const bool row_all = row_span.whole;
  const bool col_all = col_span.whole;
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  const uword in_row1       = row_all ? 0            : row_span.a;
  const uword in_row2       =                          row_span.b;
  const uword submat_n_rows = row_all ? local_n_rows : in_row2 - in_row1 + 1;
  
  const uword in_col1       = col_all ? 0            : col_span.a;
  const uword in_col2       =                          col_span.b;
  const uword submat_n_cols = col_all ? local_n_cols : in_col2 - in_col1 + 1;
  
  arma_debug_check
    (
    ( row_all ? false : ((in_row1 > in_row2) || (in_row2 >= local_n_rows)) )
    ||
    ( col_all ? false : ((in_col1 > in_col2) || (in_col2 >= local_n_cols)) )
    ,
    "subview::submat(): indices out of bounds or incorrectly used"
    );
  
  const uword base_row1 = aux_row1 + in_row1;
  const uword base_col1 = aux_col1 + in_col1;
  
  return subview<eT>(m, base_row1, base_col1, submat_n_rows, submat_n_cols);
  }



//! creation of subview (generic submatrix)
template<typename eT>
inline
const subview<eT>
subview<eT>::submat(const span& row_span, const span& col_span) const
  {
  arma_extra_debug_sigprint();
  
  const bool row_all = row_span.whole;
  const bool col_all = col_span.whole;
  
  const uword local_n_rows = n_rows;
  const uword local_n_cols = n_cols;
  
  const uword in_row1       = row_all ? 0            : row_span.a;
  const uword in_row2       =                          row_span.b;
  const uword submat_n_rows = row_all ? local_n_rows : in_row2 - in_row1 + 1;
  
  const uword in_col1       = col_all ? 0            : col_span.a;
  const uword in_col2       =                          col_span.b;
  const uword submat_n_cols = col_all ? local_n_cols : in_col2 - in_col1 + 1;
  
  arma_debug_check
    (
    ( row_all ? false : ((in_row1 > in_row2) || (in_row2 >= local_n_rows)) )
    ||
    ( col_all ? false : ((in_col1 > in_col2) || (in_col2 >= local_n_cols)) )
    ,
    "subview::submat(): indices out of bounds or incorrectly used"
    );
  
  const uword base_row1 = aux_row1 + in_row1;
  const uword base_col1 = aux_col1 + in_col1;
  
  return subview<eT>(m, base_row1, base_col1, submat_n_rows, submat_n_cols);
  }



template<typename eT>
inline
subview<eT>
subview<eT>::operator()(const span& row_span, const span& col_span)
  {
  arma_extra_debug_sigprint();
  
  return (*this).submat(row_span, col_span);
  }



template<typename eT>
inline
const subview<eT>
subview<eT>::operator()(const span& row_span, const span& col_span) const
  {
  arma_extra_debug_sigprint();
  
  return (*this).submat(row_span, col_span);
  }



template<typename eT>
inline
subview_each1< subview<eT>, 0 >
subview<eT>::each_col()
  {
  arma_extra_debug_sigprint();
  
  return subview_each1< subview<eT>, 0 >(*this);
  }



template<typename eT>
inline
subview_each1< subview<eT>, 1 >
subview<eT>::each_row()
  {
  arma_extra_debug_sigprint();
  
  return subview_each1< subview<eT>, 1 >(*this);
  }



template<typename eT>
template<typename T1>
inline
subview_each2< subview<eT>, 0, T1 >
subview<eT>::each_col(const Base<uword,T1>& indices)
  {
  arma_extra_debug_sigprint();
  
  return subview_each2< subview<eT>, 0, T1 >(*this, indices);
  }



template<typename eT>
template<typename T1>
inline
subview_each2< subview<eT>, 1, T1 >
subview<eT>::each_row(const Base<uword,T1>& indices)
  {
  arma_extra_debug_sigprint();
  
  return subview_each2< subview<eT>, 1, T1 >(*this, indices);
  }



//! apply a lambda function to each column, where each column is interpreted as a column vector
template<typename eT>
inline
void
subview<eT>::each_col(const std::function< void(Col<eT>&) >& F)
  {
  arma_extra_debug_sigprint();
  
  for(uword ii=0; ii < n_cols; ++ii)
    {
    Col<eT> tmp(colptr(ii), n_rows, false, true);
    F(tmp);
    }
  }



template<typename eT>
inline
void
subview<eT>::each_col(const std::function< void(const Col<eT>&) >& F) const
  {
  arma_extra_debug_sigprint();
  
  for(uword ii=0; ii < n_cols; ++ii)
    {
    const Col<eT> tmp(colptr(ii), n_rows, false, true);
    F(tmp);
    }
  }



//! apply a lambda function to each row, where each row is interpreted as a row vector
template<typename eT>
inline
void
subview<eT>::each_row(const std::function< void(Row<eT>&) >& F)
  {
  arma_extra_debug_sigprint();
  
  podarray<eT> array1(n_cols);
  podarray<eT> array2(n_cols);
  
  Row<eT> tmp1( array1.memptr(), n_cols, false, true );
  Row<eT> tmp2( array2.memptr(), n_cols, false, true );
  
  eT* tmp1_mem = tmp1.memptr();
  eT* tmp2_mem = tmp2.memptr();
  
  uword ii, jj;
  
  for(ii=0, jj=1; jj < n_rows; ii+=2, jj+=2)
    {
    for(uword col_id = 0; col_id < n_cols; ++col_id)
      {
      const eT* col_mem = colptr(col_id);
      
      tmp1_mem[col_id] = col_mem[ii];
      tmp2_mem[col_id] = col_mem[jj];
      }
    
    F(tmp1);
    F(tmp2);
    
    for(uword col_id = 0; col_id < n_cols; ++col_id)
      {
      eT* col_mem = colptr(col_id);
      
      col_mem[ii] = tmp1_mem[col_id];
      col_mem[jj] = tmp2_mem[col_id];
      }
    }
  
  if(ii < n_rows)
    {
    tmp1 = (*this).row(ii);
    
    F(tmp1);
    
    (*this).row(ii) = tmp1;
    }
  }



template<typename eT>
inline
void
subview<eT>::each_row(const std::function< void(const Row<eT>&) >& F) const
  {
  arma_extra_debug_sigprint();
  
  podarray<eT> array1(n_cols);
  podarray<eT> array2(n_cols);
  
  Row<eT> tmp1( array1.memptr(), n_cols, false, true );
  Row<eT> tmp2( array2.memptr(), n_cols, false, true );
  
  eT* tmp1_mem = tmp1.memptr();
  eT* tmp2_mem = tmp2.memptr();
  
  uword ii, jj;
  
  for(ii=0, jj=1; jj < n_rows; ii+=2, jj+=2)
    {
    for(uword col_id = 0; col_id < n_cols; ++col_id)
      {
      const eT* col_mem = colptr(col_id);
      
      tmp1_mem[col_id] = col_mem[ii];
      tmp2_mem[col_id] = col_mem[jj];
      }
    
    F(tmp1);
    F(tmp2);
    }
  
  if(ii < n_rows)
    {
    tmp1 = (*this).row(ii);
    
    F(tmp1);
    }
  }



//! creation of diagview (diagonal)
template<typename eT>
inline
diagview<eT>
subview<eT>::diag(const sword in_id)
  {
  arma_extra_debug_sigprint();
  
  const uword row_offset = (in_id < 0) ? uword(-in_id) : 0;
  const uword col_offset = (in_id > 0) ? uword( in_id) : 0;
  
  arma_debug_check
    (
    ((row_offset > 0) && (row_offset >= n_rows)) || ((col_offset > 0) && (col_offset >= n_cols)),
    "subview::diag(): requested diagonal out of bounds"
    );
  
  const uword len = (std::min)(n_rows - row_offset, n_cols - col_offset);
  
  const uword base_row_offset = aux_row1 + row_offset;
  const uword base_col_offset = aux_col1 + col_offset;
  
  return diagview<eT>(m, base_row_offset, base_col_offset, len);
  }



//! creation of diagview (diagonal)
template<typename eT>
inline
const diagview<eT>
subview<eT>::diag(const sword in_id) const
  {
  arma_extra_debug_sigprint();
  
  const uword row_offset = uword( (in_id < 0) ? -in_id : 0 );
  const uword col_offset = uword( (in_id > 0) ?  in_id : 0 );
  
  arma_debug_check
    (
    ((row_offset > 0) && (row_offset >= n_rows)) || ((col_offset > 0) && (col_offset >= n_cols)),
    "subview::diag(): requested diagonal out of bounds"
    );
  
  const uword len = (std::min)(n_rows - row_offset, n_cols - col_offset);
  
  const uword base_row_offset = aux_row1 + row_offset;
  const uword base_col_offset = aux_col1 + col_offset;
  
  return diagview<eT>(m, base_row_offset, base_col_offset, len);
  }



template<typename eT>
inline
void
subview<eT>::swap_rows(const uword in_row1, const uword in_row2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_row1 >= n_rows) || (in_row2 >= n_rows),
    "subview::swap_rows(): out of bounds"
    );
  
  eT* mem = (const_cast< Mat<eT>& >(m)).memptr();
  
  if(n_elem > 0)
    {
    const uword m_n_rows = m.n_rows;
    
    for(uword ucol=0; ucol < n_cols; ++ucol)
      {
      const uword offset = (aux_col1 + ucol) * m_n_rows;
      const uword pos1   = aux_row1 + in_row1 + offset;
      const uword pos2   = aux_row1 + in_row2 + offset;
      
      std::swap( access::rw(mem[pos1]), access::rw(mem[pos2]) );
      }
    }
  }



template<typename eT>
inline
void
subview<eT>::swap_cols(const uword in_col1, const uword in_col2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check
    (
    (in_col1 >= n_cols) || (in_col2 >= n_cols),
    "subview::swap_cols(): out of bounds"
    );
  
  if(n_elem > 0)
    {
    eT* ptr1 = colptr(in_col1);
    eT* ptr2 = colptr(in_col2);
    
    for(uword urow=0; urow < n_rows; ++urow)
      {
      std::swap( ptr1[urow], ptr2[urow] );
      }
    }
  }



template<typename eT>
inline
typename subview<eT>::iterator
subview<eT>::begin()
  {
  return iterator(*this, aux_row1, aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::const_iterator
subview<eT>::begin() const
  {
  return const_iterator(*this, aux_row1, aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::const_iterator
subview<eT>::cbegin() const
  {
  return const_iterator(*this, aux_row1, aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::iterator
subview<eT>::end()
  {
  return iterator(*this, aux_row1, aux_col1 + n_cols);
  }



template<typename eT>
inline
typename subview<eT>::const_iterator
subview<eT>::end() const
  {
  return const_iterator(*this, aux_row1, aux_col1 + n_cols);
  }



template<typename eT>
inline
typename subview<eT>::const_iterator
subview<eT>::cend() const
  {
  return const_iterator(*this, aux_row1, aux_col1 + n_cols);
  }



//
//
//



template<typename eT>
inline
subview<eT>::iterator::iterator()
  : M          (nullptr)
  , current_ptr(nullptr)
  , current_row(0      )
  , current_col(0      )
  , aux_row1   (0      )
  , aux_row2_p1(0      )
  {
  arma_extra_debug_sigprint();
  // Technically this iterator is invalid (it does not point to a valid element)
  }



template<typename eT>
inline
subview<eT>::iterator::iterator(const iterator& X)
  : M          (X.M          )
  , current_ptr(X.current_ptr)
  , current_row(X.current_row)
  , current_col(X.current_col)
  , aux_row1   (X.aux_row1   )
  , aux_row2_p1(X.aux_row2_p1)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview<eT>::iterator::iterator(subview<eT>& in_sv, const uword in_row, const uword in_col)
  : M          (&(const_cast< Mat<eT>& >(in_sv.m)))
  , current_ptr(&(M->at(in_row,in_col))           )
  , current_row(in_row                            )
  , current_col(in_col                            )
  , aux_row1   (in_sv.aux_row1                    )
  , aux_row2_p1(in_sv.aux_row1 + in_sv.n_rows     )
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
arma_warn_unused
eT&
subview<eT>::iterator::operator*()
  {
  return (*current_ptr);
  }



template<typename eT>
inline
typename subview<eT>::iterator&
subview<eT>::iterator::operator++()
  {
  current_row++;
  
  if(current_row == aux_row2_p1)
    {
    current_row = aux_row1;
    current_col++;
    
    current_ptr = &( (*M).at(current_row,current_col) );
    }
  else
    {
    current_ptr++;
    }
  
  return *this;
  }



template<typename eT>
inline
arma_warn_unused
typename subview<eT>::iterator
subview<eT>::iterator::operator++(int)
  {
  typename subview<eT>::iterator temp(*this);
  
  ++(*this);
  
  return temp;
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::iterator::operator==(const iterator& rhs) const
  {
  return (current_ptr == rhs.current_ptr);
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::iterator::operator!=(const iterator& rhs) const
  {
  return (current_ptr != rhs.current_ptr);
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::iterator::operator==(const const_iterator& rhs) const
  {
  return (current_ptr == rhs.current_ptr);
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::iterator::operator!=(const const_iterator& rhs) const
  {
  return (current_ptr != rhs.current_ptr);
  }



//
//
//



template<typename eT>
inline
subview<eT>::const_iterator::const_iterator()
  : M          (nullptr)
  , current_ptr(nullptr)
  , current_row(0   )
  , current_col(0   )
  , aux_row1   (0   )
  , aux_row2_p1(0   )
  {
  arma_extra_debug_sigprint();
  // Technically this iterator is invalid (it does not point to a valid element)
  }



template<typename eT>
inline
subview<eT>::const_iterator::const_iterator(const iterator& X)
  : M          (X.M          )
  , current_ptr(X.current_ptr)
  , current_row(X.current_row)
  , current_col(X.current_col)
  , aux_row1   (X.aux_row1   )
  , aux_row2_p1(X.aux_row2_p1)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview<eT>::const_iterator::const_iterator(const const_iterator& X)
  : M          (X.M          )
  , current_ptr(X.current_ptr)
  , current_row(X.current_row)
  , current_col(X.current_col)
  , aux_row1   (X.aux_row1   )
  , aux_row2_p1(X.aux_row2_p1)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview<eT>::const_iterator::const_iterator(const subview<eT>& in_sv, const uword in_row, const uword in_col)
  : M          (&(in_sv.m)                   )
  , current_ptr(&(M->at(in_row,in_col))      )
  , current_row(in_row                       )
  , current_col(in_col                       )
  , aux_row1   (in_sv.aux_row1               )
  , aux_row2_p1(in_sv.aux_row1 + in_sv.n_rows)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
arma_warn_unused
const eT&
subview<eT>::const_iterator::operator*()
  {
  return (*current_ptr);
  }



template<typename eT>
inline
typename subview<eT>::const_iterator&
subview<eT>::const_iterator::operator++()
  {
  current_row++;
  
  if(current_row == aux_row2_p1)
    {
    current_row = aux_row1;
    current_col++;
    
    current_ptr = &( (*M).at(current_row,current_col) );
    }
  else
    {
    current_ptr++;
    }
  
  return *this;
  }



template<typename eT>
inline
arma_warn_unused
typename subview<eT>::const_iterator
subview<eT>::const_iterator::operator++(int)
  {
  typename subview<eT>::const_iterator temp(*this);
  
  ++(*this);
  
  return temp;
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_iterator::operator==(const iterator& rhs) const
  {
  return (current_ptr == rhs.current_ptr);
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_iterator::operator!=(const iterator& rhs) const
  {
  return (current_ptr != rhs.current_ptr);
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_iterator::operator==(const const_iterator& rhs) const
  {
  return (current_ptr == rhs.current_ptr);
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_iterator::operator!=(const const_iterator& rhs) const
  {
  return (current_ptr != rhs.current_ptr);
  }



//
//
//



template<typename eT>
inline
subview<eT>::row_iterator::row_iterator()
  : M          (nullptr)
  , current_row(0   )
  , current_col(0   )
  , aux_col1   (0   )
  , aux_col2_p1(0   )
  {
  arma_extra_debug_sigprint();
  // Technically this iterator is invalid (it does not point to a valid element)
  }



template<typename eT>
inline
subview<eT>::row_iterator::row_iterator(const row_iterator& X)
  : M          (X.M          )
  , current_row(X.current_row)
  , current_col(X.current_col)
  , aux_col1   (X.aux_col1   )
  , aux_col2_p1(X.aux_col2_p1)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview<eT>::row_iterator::row_iterator(subview<eT>& in_sv, const uword in_row, const uword in_col)
  : M          (&(const_cast< Mat<eT>& >(in_sv.m)))
  , current_row(in_row                            )
  , current_col(in_col                            )
  , aux_col1   (in_sv.aux_col1                    )
  , aux_col2_p1(in_sv.aux_col1 + in_sv.n_cols     )
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
arma_warn_unused
eT&
subview<eT>::row_iterator::operator*()
  {
  return M->at(current_row,current_col);
  }



template<typename eT>
inline
typename subview<eT>::row_iterator&
subview<eT>::row_iterator::operator++()
  {
  current_col++;
  
  if(current_col == aux_col2_p1)
    {
    current_col = aux_col1;
    current_row++;
    }
  
  return *this;
  }



template<typename eT>
inline
arma_warn_unused
typename subview<eT>::row_iterator
subview<eT>::row_iterator::operator++(int)
  {
  typename subview<eT>::row_iterator temp(*this);
  
  ++(*this);
  
  return temp;
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::row_iterator::operator==(const row_iterator& rhs) const
  {
  return ( (current_row == rhs.current_row) && (current_col == rhs.current_col) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::row_iterator::operator!=(const row_iterator& rhs) const
  {
  return ( (current_row != rhs.current_row) || (current_col != rhs.current_col) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::row_iterator::operator==(const const_row_iterator& rhs) const
  {
  return ( (current_row == rhs.current_row) && (current_col == rhs.current_col) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::row_iterator::operator!=(const const_row_iterator& rhs) const
  {
  return ( (current_row != rhs.current_row) || (current_col != rhs.current_col) );
  }



//
//
//



template<typename eT>
inline
subview<eT>::const_row_iterator::const_row_iterator()
  : M          (nullptr)
  , current_row(0   )
  , current_col(0   )
  , aux_col1   (0   )
  , aux_col2_p1(0   )
  {
  arma_extra_debug_sigprint();
  // Technically this iterator is invalid (it does not point to a valid element)
  }



template<typename eT>
inline
subview<eT>::const_row_iterator::const_row_iterator(const row_iterator& X)
  : M          (X.M          )
  , current_row(X.current_row)
  , current_col(X.current_col)
  , aux_col1   (X.aux_col1   )
  , aux_col2_p1(X.aux_col2_p1)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview<eT>::const_row_iterator::const_row_iterator(const const_row_iterator& X)
  : M          (X.M          )
  , current_row(X.current_row)
  , current_col(X.current_col)
  , aux_col1   (X.aux_col1   )
  , aux_col2_p1(X.aux_col2_p1)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview<eT>::const_row_iterator::const_row_iterator(const subview<eT>& in_sv, const uword in_row, const uword in_col)
  : M          (&(in_sv.m)                   )
  , current_row(in_row                       )
  , current_col(in_col                       )
  , aux_col1   (in_sv.aux_col1               )
  , aux_col2_p1(in_sv.aux_col1 + in_sv.n_cols)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
arma_warn_unused
const eT&
subview<eT>::const_row_iterator::operator*() const
  {
  return M->at(current_row,current_col);
  }



template<typename eT>
inline
typename subview<eT>::const_row_iterator&
subview<eT>::const_row_iterator::operator++()
  {
  current_col++;
  
  if(current_col == aux_col2_p1)
    {
    current_col = aux_col1;
    current_row++;
    }
  
  return *this;
  }



template<typename eT>
inline
arma_warn_unused
typename subview<eT>::const_row_iterator
subview<eT>::const_row_iterator::operator++(int)
  {
  typename subview<eT>::const_row_iterator temp(*this);
  
  ++(*this);
  
  return temp;
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_row_iterator::operator==(const row_iterator& rhs) const
  {
  return ( (current_row == rhs.current_row) && (current_col == rhs.current_col) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_row_iterator::operator!=(const row_iterator& rhs) const
  {
  return ( (current_row != rhs.current_row) || (current_col != rhs.current_col) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_row_iterator::operator==(const const_row_iterator& rhs) const
  {
  return ( (current_row == rhs.current_row) && (current_col == rhs.current_col) );
  }



template<typename eT>
inline
arma_warn_unused
bool
subview<eT>::const_row_iterator::operator!=(const const_row_iterator& rhs) const
  {
  return ( (current_row != rhs.current_row) || (current_col != rhs.current_col) );
  }



//
//
//



template<typename eT>
inline
subview_col<eT>::subview_col(const Mat<eT>& in_m, const uword in_col)
  : subview<eT>(in_m, 0, in_col, in_m.n_rows, 1)
  , colmem(subview<eT>::colptr(0)) 
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview_col<eT>::subview_col(const Mat<eT>& in_m, const uword in_col, const uword in_row1, const uword in_n_rows)
  : subview<eT>(in_m, in_row1, in_col, in_n_rows, 1)
  , colmem(subview<eT>::colptr(0)) 
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview_col<eT>::subview_col(const subview_col<eT>& in)
  : subview<eT>(in)   // interprets 'subview_col' as 'subview'
  , colmem(in.colmem)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview_col<eT>::subview_col(subview_col<eT>&& in)
  : subview<eT>(std::move(in))  // interprets 'subview_col' as 'subview'
  , colmem(in.colmem)
  {
  arma_extra_debug_sigprint();
  
  access::rw(in.colmem) = nullptr;
  }



template<typename eT>
inline
void
subview_col<eT>::operator=(const subview<eT>& X)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>::operator=(X);
  }



template<typename eT>
inline
void
subview_col<eT>::operator=(const subview_col<eT>& X)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>::operator=(X); // interprets 'subview_col' as 'subview'
  }



template<typename eT>
inline
void
subview_col<eT>::operator=(const std::initializer_list<eT>& list)
  {
  arma_extra_debug_sigprint();
  
  const uword N = uword(list.size());
  
  arma_debug_assert_same_size(subview<eT>::n_rows, subview<eT>::n_cols, N, 1, "copy into submatrix");
  
  arrayops::copy( access::rwp(colmem), list.begin(), N );
  }



template<typename eT>
inline
void
subview_col<eT>::operator=(const eT val)
  {
  arma_extra_debug_sigprint();
  
  if(subview<eT>::n_elem != 1)
    {
    arma_debug_assert_same_size(subview<eT>::n_rows, subview<eT>::n_cols, 1, 1, "copy into submatrix");
    }
  
  access::rw( colmem[0] ) = val;
  }



template<typename eT>
template<typename T1>
inline
void
subview_col<eT>::operator=(const Base<eT,T1>& X)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>::operator=(X);
  }



template<typename eT>
template<typename T1, typename gen_type>
inline
typename enable_if2< is_same_type<typename T1::elem_type, eT>::value, void>::result
subview_col<eT>::operator= (const Gen<T1,gen_type>& in)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_assert_same_size(subview<eT>::n_rows, uword(1), in.n_rows, (in.is_col ? uword(1) : in.n_cols), "copy into submatrix");
  
  in.apply(*this);
  }



template<typename eT>
arma_inline
const Op<subview_col<eT>,op_htrans>
subview_col<eT>::t() const
  {
  return Op<subview_col<eT>,op_htrans>(*this);
  }



template<typename eT>
arma_inline
const Op<subview_col<eT>,op_htrans>
subview_col<eT>::ht() const
  {
  return Op<subview_col<eT>,op_htrans>(*this);
  }



template<typename eT>
arma_inline
const Op<subview_col<eT>,op_strans>
subview_col<eT>::st() const
  {
  return Op<subview_col<eT>,op_strans>(*this);
  }



template<typename eT>
arma_inline
const Op<subview_col<eT>,op_strans>
subview_col<eT>::as_row() const
  {
  return Op<subview_col<eT>,op_strans>(*this);
  }



template<typename eT>
inline
void
subview_col<eT>::fill(const eT val)
  {
  arma_extra_debug_sigprint();
  
  arrayops::inplace_set( access::rwp(colmem), val, subview<eT>::n_rows );
  }



template<typename eT>
inline
void
subview_col<eT>::zeros()
  {
  arma_extra_debug_sigprint();
  
  arrayops::fill_zeros( access::rwp(colmem), subview<eT>::n_rows );
  }



template<typename eT>
inline
void
subview_col<eT>::ones()
  {
  arma_extra_debug_sigprint();
  
  arrayops::inplace_set( access::rwp(colmem), eT(1), subview<eT>::n_rows );
  }



template<typename eT>
arma_inline
eT
subview_col<eT>::at_alt(const uword ii) const
  {
  const eT* colmem_aligned = colmem;
  memory::mark_as_aligned(colmem_aligned);
  
  return colmem_aligned[ii];
  }



template<typename eT>
arma_inline
eT&
subview_col<eT>::operator[](const uword ii)
  {
  return access::rw( colmem[ii] );
  }



template<typename eT>
arma_inline
eT
subview_col<eT>::operator[](const uword ii) const
  {
  return colmem[ii];
  }



template<typename eT>
inline
eT&
subview_col<eT>::operator()(const uword ii)
  {
  arma_debug_check( (ii >= subview<eT>::n_elem), "subview::operator(): index out of bounds" );
    
  return access::rw( colmem[ii] );
  }



template<typename eT>
inline
eT
subview_col<eT>::operator()(const uword ii) const
  {
  arma_debug_check( (ii >= subview<eT>::n_elem), "subview::operator(): index out of bounds" );
  
  return colmem[ii];
  }



template<typename eT>
inline
eT&
subview_col<eT>::operator()(const uword in_row, const uword in_col)
  {
  arma_debug_check( ((in_row >= subview<eT>::n_rows) || (in_col > 0)), "subview::operator(): index out of bounds" );
  
  return access::rw( colmem[in_row] );
  }



template<typename eT>
inline
eT
subview_col<eT>::operator()(const uword in_row, const uword in_col) const
  {
  arma_debug_check( ((in_row >= subview<eT>::n_rows) || (in_col > 0)), "subview::operator(): index out of bounds" );
  
  return colmem[in_row];
  }



template<typename eT>
inline
eT&
subview_col<eT>::at(const uword in_row, const uword)
  {
  return access::rw( colmem[in_row] );
  }



template<typename eT>
inline
eT
subview_col<eT>::at(const uword in_row, const uword) const
  {
  return colmem[in_row];
  }



template<typename eT>
arma_inline
eT*
subview_col<eT>::colptr(const uword)
  {
  return const_cast<eT*>(colmem);
  }
  
  
template<typename eT>
arma_inline
const eT*
subview_col<eT>::colptr(const uword) const
  {
  return colmem;
  }


template<typename eT>
inline
subview_col<eT>
subview_col<eT>::rows(const uword in_row1, const uword in_row2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_row1 > in_row2) || (in_row2 >= subview<eT>::n_rows) ), "subview_col::rows(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  
  const uword base_row1 = this->aux_row1 + in_row1;
  
  return subview_col<eT>(this->m, this->aux_col1, base_row1, subview_n_rows);
  }



template<typename eT>
inline
const subview_col<eT>
subview_col<eT>::rows(const uword in_row1, const uword in_row2) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_row1 > in_row2) || (in_row2 >= subview<eT>::n_rows) ), "subview_col::rows(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  
  const uword base_row1 = this->aux_row1 + in_row1;
  
  return subview_col<eT>(this->m, this->aux_col1, base_row1, subview_n_rows);
  }



template<typename eT>
inline
subview_col<eT>
subview_col<eT>::subvec(const uword in_row1, const uword in_row2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_row1 > in_row2) || (in_row2 >= subview<eT>::n_rows) ), "subview_col::subvec(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  
  const uword base_row1 = this->aux_row1 + in_row1;
  
  return subview_col<eT>(this->m, this->aux_col1, base_row1, subview_n_rows);
  }



template<typename eT>
inline
const subview_col<eT>
subview_col<eT>::subvec(const uword in_row1, const uword in_row2) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_row1 > in_row2) || (in_row2 >= subview<eT>::n_rows) ), "subview_col::subvec(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_rows = in_row2 - in_row1 + 1;
  
  const uword base_row1 = this->aux_row1 + in_row1;
  
  return subview_col<eT>(this->m, this->aux_col1, base_row1, subview_n_rows);
  }



template<typename eT>
inline
subview_col<eT>
subview_col<eT>::subvec(const uword start_row, const SizeMat& s)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (s.n_cols != 1), "subview_col::subvec(): given size does not specify a column vector" );
  
  arma_debug_check( ( (start_row >= subview<eT>::n_rows) || ((start_row + s.n_rows) > subview<eT>::n_rows) ), "subview_col::subvec(): size out of bounds" );
  
  const uword base_row1 = this->aux_row1 + start_row;
  
  return subview_col<eT>(this->m, this->aux_col1, base_row1, s.n_rows);
  }



template<typename eT>
inline
const subview_col<eT>
subview_col<eT>::subvec(const uword start_row, const SizeMat& s) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (s.n_cols != 1), "subview_col::subvec(): given size does not specify a column vector" );
  
  arma_debug_check( ( (start_row >= subview<eT>::n_rows) || ((start_row + s.n_rows) > subview<eT>::n_rows) ), "subview_col::subvec(): size out of bounds" );
  
  const uword base_row1 = this->aux_row1 + start_row;
  
  return subview_col<eT>(this->m, this->aux_col1, base_row1, s.n_rows);
  }



template<typename eT>
inline
subview_col<eT>
subview_col<eT>::head(const uword N)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_rows), "subview_col::head(): size out of bounds" );
  
  return subview_col<eT>(this->m, this->aux_col1, this->aux_row1, N);
  }



template<typename eT>
inline
const subview_col<eT>
subview_col<eT>::head(const uword N) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_rows), "subview_col::head(): size out of bounds" );
  
  return subview_col<eT>(this->m, this->aux_col1, this->aux_row1, N);
  }



template<typename eT>
inline
subview_col<eT>
subview_col<eT>::tail(const uword N)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_rows), "subview_col::tail(): size out of bounds" );
  
  const uword start_row = subview<eT>::aux_row1 + subview<eT>::n_rows - N;
  
  return subview_col<eT>(this->m, this->aux_col1, start_row, N);
  }



template<typename eT>
inline
const subview_col<eT>
subview_col<eT>::tail(const uword N) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_rows), "subview_col::tail(): size out of bounds" );
  
  const uword start_row = subview<eT>::aux_row1 + subview<eT>::n_rows - N;
  
  return subview_col<eT>(this->m, this->aux_col1, start_row, N);
  }



template<typename eT>
inline
arma_warn_unused
eT
subview_col<eT>::min() const
  {
  arma_extra_debug_sigprint();
  
  if(subview<eT>::n_elem == 0)
    {
    arma_debug_check(true, "min(): object has no elements");
    
    return Datum<eT>::nan;
    }
  
  return op_min::direct_min(colmem, subview<eT>::n_elem);
  }



template<typename eT>
inline
arma_warn_unused
eT
subview_col<eT>::max() const
  {
  arma_extra_debug_sigprint();
  
  if(subview<eT>::n_elem == 0)
    {
    arma_debug_check(true, "max(): object has no elements");
    
    return Datum<eT>::nan;
    }
  
  return op_max::direct_max(colmem, subview<eT>::n_elem);
  }



template<typename eT>
inline
eT
subview_col<eT>::min(uword& index_of_min_val) const
  {
  arma_extra_debug_sigprint();
  
  if(subview<eT>::n_elem == 0)
    {
    arma_debug_check(true, "min(): object has no elements");
    
    index_of_min_val = uword(0);
    
    return Datum<eT>::nan;
    }
  else
    {
    return op_min::direct_min(colmem, subview<eT>::n_elem, index_of_min_val);
    }
  }



template<typename eT>
inline
eT
subview_col<eT>::max(uword& index_of_max_val) const
  {
  arma_extra_debug_sigprint();
  
  if(subview<eT>::n_elem == 0)
    {
    arma_debug_check(true, "max(): object has no elements");
    
    index_of_max_val = uword(0);
    
    return Datum<eT>::nan;
    }
  else
    {
    return op_max::direct_max(colmem, subview<eT>::n_elem, index_of_max_val);
    }
  }



template<typename eT>
inline
arma_warn_unused
uword
subview_col<eT>::index_min() const
  {
  arma_extra_debug_sigprint();
  
  uword index = 0;
  
  if(subview<eT>::n_elem == 0)
    {
    arma_debug_check(true, "index_min(): object has no elements");
    }
  else
    {
    op_min::direct_min(colmem, subview<eT>::n_elem, index);
    }
  
  return index;
  }



template<typename eT>
inline
arma_warn_unused
uword
subview_col<eT>::index_max() const
  {
  arma_extra_debug_sigprint();
  
  uword index = 0;
  
  if(subview<eT>::n_elem == 0)
    {
    arma_debug_check(true, "index_max(): object has no elements");
    }
  else
    {
    op_max::direct_max(colmem, subview<eT>::n_elem, index);
    }
  
  return index;
  }



//
//
//



template<typename eT>
inline
subview_row<eT>::subview_row(const Mat<eT>& in_m, const uword in_row)
  : subview<eT>(in_m, in_row, 0, 1, in_m.n_cols)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview_row<eT>::subview_row(const Mat<eT>& in_m, const uword in_row, const uword in_col1, const uword in_n_cols)
  : subview<eT>(in_m, in_row, in_col1, 1, in_n_cols)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview_row<eT>::subview_row(const subview_row<eT>& in)
  : subview<eT>(in)   // interprets 'subview_row' as 'subview'
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
subview_row<eT>::subview_row(subview_row<eT>&& in)
  : subview<eT>(std::move(in))  // interprets 'subview_row' as 'subview'
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
void
subview_row<eT>::operator=(const subview<eT>& X)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>::operator=(X);
  }



template<typename eT>
inline
void
subview_row<eT>::operator=(const subview_row<eT>& X)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>::operator=(X); // interprets 'subview_row' as 'subview'
  }



template<typename eT>
inline
void
subview_row<eT>::operator=(const eT val)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>::operator=(val); // interprets 'subview_row' as 'subview'
  }



template<typename eT>
inline
void
subview_row<eT>::operator=(const std::initializer_list<eT>& list)
  {
  arma_extra_debug_sigprint();
  
  const uword N = uword(list.size());
  
  arma_debug_assert_same_size(subview<eT>::n_rows, subview<eT>::n_cols, 1, N, "copy into submatrix");
  
  auto it = list.begin();
  
  for(uword ii=0; ii < N; ++ii)
    {
    (*this).operator[](ii) = (*it);
    ++it;
    }
  }



template<typename eT>
template<typename T1>
inline
void
subview_row<eT>::operator=(const Base<eT,T1>& X)
  {
  arma_extra_debug_sigprint();
  
  subview<eT>::operator=(X);
  }



template<typename eT>
template<typename T1, typename gen_type>
inline
typename enable_if2< is_same_type<typename T1::elem_type, eT>::value, void>::result
subview_row<eT>::operator= (const Gen<T1,gen_type>& in)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_assert_same_size(uword(1), subview<eT>::n_cols, (in.is_row ? uword(1) : in.n_rows), in.n_cols, "copy into submatrix");
  
  in.apply(*this);
  }



template<typename eT>
arma_inline
const Op<subview_row<eT>,op_htrans>
subview_row<eT>::t() const
  {
  return Op<subview_row<eT>,op_htrans>(*this);
  }



template<typename eT>
arma_inline
const Op<subview_row<eT>,op_htrans>
subview_row<eT>::ht() const
  {
  return Op<subview_row<eT>,op_htrans>(*this);
  }



template<typename eT>
arma_inline
const Op<subview_row<eT>,op_strans>
subview_row<eT>::st() const
  {
  return Op<subview_row<eT>,op_strans>(*this);
  }



template<typename eT>
arma_inline
const Op<subview_row<eT>,op_strans>
subview_row<eT>::as_col() const
  {
  return Op<subview_row<eT>,op_strans>(*this);
  }



template<typename eT>
inline
eT
subview_row<eT>::at_alt(const uword ii) const
  {
  const uword index = (ii + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return subview<eT>::m.mem[index];
  }



template<typename eT>
inline
eT&
subview_row<eT>::operator[](const uword ii)
  {
  const uword index = (ii + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return access::rw( (const_cast< Mat<eT>& >(subview<eT>::m)).mem[index] );
  }



template<typename eT>
inline
eT
subview_row<eT>::operator[](const uword ii) const
  {
  const uword index = (ii + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return subview<eT>::m.mem[index];
  }



template<typename eT>
inline
eT&
subview_row<eT>::operator()(const uword ii)
  {
  arma_debug_check( (ii >= subview<eT>::n_elem), "subview::operator(): index out of bounds" );
    
  const uword index = (ii + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return access::rw( (const_cast< Mat<eT>& >(subview<eT>::m)).mem[index] );
  }



template<typename eT>
inline
eT
subview_row<eT>::operator()(const uword ii) const
  {
  arma_debug_check( (ii >= subview<eT>::n_elem), "subview::operator(): index out of bounds" );
  
  const uword index = (ii + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return subview<eT>::m.mem[index];
  }



template<typename eT>
inline
eT&
subview_row<eT>::operator()(const uword in_row, const uword in_col)
  {
  arma_debug_check( ((in_row > 0) || (in_col >= subview<eT>::n_cols)), "subview::operator(): index out of bounds" );
  
  const uword index = (in_col + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return access::rw( (const_cast< Mat<eT>& >(subview<eT>::m)).mem[index] );
  }



template<typename eT>
inline
eT
subview_row<eT>::operator()(const uword in_row, const uword in_col) const
  {
  arma_debug_check( ((in_row > 0) || (in_col >= subview<eT>::n_cols)), "subview::operator(): index out of bounds" );
  
  const uword index = (in_col + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return subview<eT>::m.mem[index];
  }



template<typename eT>
inline
eT&
subview_row<eT>::at(const uword, const uword in_col)
  {
  const uword index = (in_col + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return access::rw( (const_cast< Mat<eT>& >(subview<eT>::m)).mem[index] );
  }



template<typename eT>
inline
eT
subview_row<eT>::at(const uword, const uword in_col) const
  {
  const uword index = (in_col + (subview<eT>::aux_col1))*(subview<eT>::m).n_rows + (subview<eT>::aux_row1);
  
  return subview<eT>::m.mem[index];
  }



template<typename eT>
inline
subview_row<eT>
subview_row<eT>::cols(const uword in_col1, const uword in_col2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_col1 > in_col2) || (in_col2 >= subview<eT>::n_cols) ), "subview_row::cols(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  
  const uword base_col1 = this->aux_col1 + in_col1;
  
  return subview_row<eT>(this->m, this->aux_row1, base_col1, subview_n_cols);
  }



template<typename eT>
inline
const subview_row<eT>
subview_row<eT>::cols(const uword in_col1, const uword in_col2) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_col1 > in_col2) || (in_col2 >= subview<eT>::n_cols) ), "subview_row::cols(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  
  const uword base_col1 = this->aux_col1 + in_col1;
  
  return subview_row<eT>(this->m, this->aux_row1, base_col1, subview_n_cols);
  }



template<typename eT>
inline
subview_row<eT>
subview_row<eT>::subvec(const uword in_col1, const uword in_col2)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_col1 > in_col2) || (in_col2 >= subview<eT>::n_cols) ), "subview_row::subvec(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  
  const uword base_col1 = this->aux_col1 + in_col1;
  
  return subview_row<eT>(this->m, this->aux_row1, base_col1, subview_n_cols);
  }



template<typename eT>
inline
const subview_row<eT>
subview_row<eT>::subvec(const uword in_col1, const uword in_col2) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( ( (in_col1 > in_col2) || (in_col2 >= subview<eT>::n_cols) ), "subview_row::subvec(): indices out of bounds or incorrectly used" );
  
  const uword subview_n_cols = in_col2 - in_col1 + 1;
  
  const uword base_col1 = this->aux_col1 + in_col1;
  
  return subview_row<eT>(this->m, this->aux_row1, base_col1, subview_n_cols);
  }



template<typename eT>
inline
subview_row<eT>
subview_row<eT>::subvec(const uword start_col, const SizeMat& s)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (s.n_rows != 1), "subview_row::subvec(): given size does not specify a row vector" );
  
  arma_debug_check( ( (start_col >= subview<eT>::n_cols) || ((start_col + s.n_cols) > subview<eT>::n_cols) ), "subview_row::subvec(): size out of bounds" );
  
  const uword base_col1 = this->aux_col1 + start_col;
  
  return subview_row<eT>(this->m, this->aux_row1, base_col1, s.n_cols);
  }



template<typename eT>
inline
const subview_row<eT>
subview_row<eT>::subvec(const uword start_col, const SizeMat& s) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (s.n_rows != 1), "subview_row::subvec(): given size does not specify a row vector" );
  
  arma_debug_check( ( (start_col >= subview<eT>::n_cols) || ((start_col + s.n_cols) > subview<eT>::n_cols) ), "subview_row::subvec(): size out of bounds" );
  
  const uword base_col1 = this->aux_col1 + start_col;
  
  return subview_row<eT>(this->m, this->aux_row1, base_col1, s.n_cols);
  }



template<typename eT>
inline
subview_row<eT>
subview_row<eT>::head(const uword N)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_cols), "subview_row::head(): size out of bounds" );
  
  return subview_row<eT>(this->m, this->aux_row1, this->aux_col1, N);
  }



template<typename eT>
inline
const subview_row<eT>
subview_row<eT>::head(const uword N) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_cols), "subview_row::head(): size out of bounds" );
  
  return subview_row<eT>(this->m, this->aux_row1, this->aux_col1, N);
  }



template<typename eT>
inline
subview_row<eT>
subview_row<eT>::tail(const uword N)
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_cols), "subview_row::tail(): size out of bounds" );
  
  const uword start_col = subview<eT>::aux_col1 + subview<eT>::n_cols - N;
  
  return subview_row<eT>(this->m, this->aux_row1, start_col, N);
  }



template<typename eT>
inline
const subview_row<eT>
subview_row<eT>::tail(const uword N) const
  {
  arma_extra_debug_sigprint();
  
  arma_debug_check( (N > subview<eT>::n_cols), "subview_row::tail(): size out of bounds" );
  
  const uword start_col = subview<eT>::aux_col1 + subview<eT>::n_cols - N;
  
  return subview_row<eT>(this->m, this->aux_row1, start_col, N);
  }



template<typename eT>
inline
arma_warn_unused
uword
subview_row<eT>::index_min() const
  {
  const Proxy< subview_row<eT> > P(*this);
  
  uword index = 0;
  
  if(P.get_n_elem() == 0)
    {
    arma_debug_check(true, "index_min(): object has no elements");
    }
  else
    {
    op_min::min_with_index(P, index);
    }
  
  return index;
  }



template<typename eT>
inline
arma_warn_unused
uword
subview_row<eT>::index_max() const
  {
  const Proxy< subview_row<eT> > P(*this);
  
  uword index = 0;
  
  if(P.get_n_elem() == 0)
    {
    arma_debug_check(true, "index_max(): object has no elements");
    }
  else
    {
    op_max::max_with_index(P, index);
    }
  
  return index;
  }



template<typename eT>
inline
typename subview<eT>::row_iterator
subview_row<eT>::begin()
  {
  return typename subview<eT>::row_iterator(*this, subview<eT>::aux_row1, subview<eT>::aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::const_row_iterator
subview_row<eT>::begin() const
  {
  return typename subview<eT>::const_row_iterator(*this, subview<eT>::aux_row1, subview<eT>::aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::const_row_iterator
subview_row<eT>::cbegin() const
  {
  return typename subview<eT>::const_row_iterator(*this, subview<eT>::aux_row1, subview<eT>::aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::row_iterator
subview_row<eT>::end()
  {
  return typename subview<eT>::row_iterator(*this, subview<eT>::aux_row1 + subview<eT>::n_rows, subview<eT>::aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::const_row_iterator
subview_row<eT>::end() const
  {
  return typename subview<eT>::const_row_iterator(*this, subview<eT>::aux_row1 + subview<eT>::n_rows, subview<eT>::aux_col1);
  }



template<typename eT>
inline
typename subview<eT>::const_row_iterator
subview_row<eT>::cend() const
  {
  return typename subview<eT>::const_row_iterator(*this, subview<eT>::aux_row1 + subview<eT>::n_rows, subview<eT>::aux_col1);
  }



//
//
//



template<typename eT>
inline
subview_row_strans<eT>::subview_row_strans(const subview_row<eT>& in_sv_row)
  : sv_row(in_sv_row       )
  , n_rows(in_sv_row.n_cols)
  , n_elem(in_sv_row.n_elem)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
void
subview_row_strans<eT>::extract(Mat<eT>& out) const
  {
  arma_extra_debug_sigprint();
  
  // NOTE: this function assumes that matrix 'out' has already been set to the correct size
  
  const Mat<eT>& X = sv_row.m;
  
  eT* out_mem = out.memptr();
  
  const uword row           = sv_row.aux_row1;
  const uword start_col     = sv_row.aux_col1;
  const uword sv_row_n_cols = sv_row.n_cols;
  
  uword ii,jj;
  
  for(ii=0, jj=1; jj < sv_row_n_cols; ii+=2, jj+=2)
    {
    const eT tmp1 = X.at(row, start_col+ii);
    const eT tmp2 = X.at(row, start_col+jj);
    
    out_mem[ii] = tmp1;
    out_mem[jj] = tmp2;
    }
  
  if(ii < sv_row_n_cols)
    {
    out_mem[ii] = X.at(row, start_col+ii);
    }
  }



template<typename eT>
inline
eT
subview_row_strans<eT>::at_alt(const uword ii) const
  {
  return sv_row[ii];
  }



template<typename eT>
inline
eT
subview_row_strans<eT>::operator[](const uword ii) const
  {
  return sv_row[ii];
  }



template<typename eT>
inline
eT
subview_row_strans<eT>::operator()(const uword ii) const
  {
  return sv_row(ii);
  }



template<typename eT>
inline
eT
subview_row_strans<eT>::operator()(const uword in_row, const uword in_col) const
  {
  return sv_row(in_col, in_row);  // deliberately swapped
  }



template<typename eT>
inline
eT
subview_row_strans<eT>::at(const uword in_row, const uword) const
  {
  return sv_row.at(0, in_row);  // deliberately swapped
  }



//
//
//



template<typename eT>
inline
subview_row_htrans<eT>::subview_row_htrans(const subview_row<eT>& in_sv_row)
  : sv_row(in_sv_row       )
  , n_rows(in_sv_row.n_cols)
  , n_elem(in_sv_row.n_elem)
  {
  arma_extra_debug_sigprint();
  }



template<typename eT>
inline
void
subview_row_htrans<eT>::extract(Mat<eT>& out) const
  {
  arma_extra_debug_sigprint();
  
  // NOTE: this function assumes that matrix 'out' has already been set to the correct size
  
  const Mat<eT>& X = sv_row.m;
  
  eT* out_mem = out.memptr();
  
  const uword row           = sv_row.aux_row1;
  const uword start_col     = sv_row.aux_col1;
  const uword sv_row_n_cols = sv_row.n_cols;
  
  for(uword ii=0; ii < sv_row_n_cols; ++ii)
    {
    out_mem[ii] = access::alt_conj( X.at(row, start_col+ii) );
    }
  }



template<typename eT>
inline
eT
subview_row_htrans<eT>::at_alt(const uword ii) const
  {
  return access::alt_conj( sv_row[ii] );
  }



template<typename eT>
inline
eT
subview_row_htrans<eT>::operator[](const uword ii) const
  {
  return access::alt_conj( sv_row[ii] );
  }



template<typename eT>
inline
eT
subview_row_htrans<eT>::operator()(const uword ii) const
  {
  return access::alt_conj( sv_row(ii) );
  }



template<typename eT>
inline
eT
subview_row_htrans<eT>::operator()(const uword in_row, const uword in_col) const
  {
  return access::alt_conj( sv_row(in_col, in_row) );  // deliberately swapped
  }



template<typename eT>
inline
eT
subview_row_htrans<eT>::at(const uword in_row, const uword) const
  {
  return access::alt_conj( sv_row.at(0, in_row) );  // deliberately swapped
  }



//! @}
