def factorize_and_solve(self,A,b):
        """
        Factorizes A and sovles Ax=b.

        Parameters
        ----------
        A : matrix
        b : ndarray

        Returns
        -------
        x : ndarray
        """

        A = coo_matrix(A)

        x = b.copy()
        self.mumps.set_centralized_assembled_values(A.data)
        self.mumps.set_rhs(x)
        self.mumps.run(job=5)

        return x