;;; DIVIDE (f fl &optional (pred #'lex>) (ring *coefficient-ring*)   [FUNCTION]
;;;         &aux (s (length fl)))
;;;    Divide polynomial F by a list of polynomials FL; use predicate PRED
;;;    to sort monomials; assumes that the polynomials have initially been
;;;    sorted according to PRED. It returnes multiple values. The first
;;;    value is a list of quotients A.  The second value is the remainder R.
;;;    These object satisfy the quation F = SUM A[J]*FL[I] + R.
;;;
;;; POLY-EXACT-DIVIDE (f g &optional (order #'lex>)                  [FUNCTION]
;;;                    (ring *coefficient-ring*))
;;;    Divide a polynomial F by another polynomial G. Assume that exact
;;;    division with no remainder is possible. Returns the quotient.
;;;