Returns a new :py:class:`cspmatrix` object with a reference to the same
        symbolic factorization, but with a copy of the array
        that stores the numerical values.

def copy(self):
        """
        Returns a new :py:class:`cspmatrix` object with a reference to the same
        symbolic factorization, but with a copy of the array
        that stores the numerical values.
        """
        return cspmatrix(self.symb, blkval = +self.blkval, factor = self.is_factor)