/*!
     * \brief Update vector with A = alpha*A + beta*B + gamma*C.
     */
    static void update( vector_type& A, const scalar_type& alpha,
    			const vector_type& B, const scalar_type& beta,
    			const vector_type& C, const scalar_type& gamma )
    {
	A.update( beta, B, gamma, C, alpha );
    }