inline
  Matrix<C>::Matrix(const SymmetricMatrix<C>& M)
    : entries_(M.row_dimension()*M.column_dimension()),
      rowdim_(M.row_dimension()), coldim_(M.column_dimension())
  {
    for (size_type i(0); i < rowdim_; i++)
      for (size_type j(0); j <= i; j++)
	{
	  this->operator () (i, j) = this->operator () (j, i) = M(i, j);
	}
  }