namespace mlpack
  {
  namespace ind_sub
  {
  #if (true)
  inline
  uvec
  ind3sub(const SizeMat& s, const uword i)
    {
    arma_extra_debug_sigprint();

    arma_debug_check( (i >= (s.n_rows * s.n_cols) ), "ind2sub(): index out of range" );

    uvec out(2);

    out[0] = i % s.n_rows;
    out[1] = i / s.n_rows;

    return out;
    }

  uvec
  ind2sub(const SizeCube& s, const uword i)
    {
    arma_extra_debug_sigprint();

    arma_debug_check( (i >= (s.n_rows * s.n_cols * s.n_slices) ), "ind2sub(): index out of range" );

    const uword n_elem_slice = s.n_rows * s.n_cols;

    const uword slice  = i / n_elem_slice;
    const uword j      = i - (slice * n_elem_slice);
    const uword row    = j % s.n_rows;
    const uword col    = j / s.n_rows;

    uvec out(3);

    out[0] = row;
    out[1] = col;
    out[2] = slice;

    return out;
    }


  arma_inline
  uword
  sub2ind(const SizeMat& s, const uword row, const uword col)
    {
    arma_extra_debug_sigprint();

    arma_debug_check( ((row >= s.n_rows) || (col >= s.n_cols)), "sub2ind(): subscript out of range" );

    return uword(row + col*s.n_rows);
    }


  arma_inline
  uword
  sub2ind(const SizeCube& s, const uword row, const uword col, const uword slice)
    {
    arma_extra_debug_sigprint();

    arma_debug_check( ((row >= s.n_rows) || (col >= s.n_cols) || (slice >= s.n_slices)), "sub2ind(): subscript out of range" );

    return uword( (slice * s.n_rows * s.n_cols) + (col * s.n_rows) + row );
    }
#endif
 } // end namespace ind_sub
 } // end namespace mlpack