public static CasPolynomial PolyProd(CasPolynomial poly1, CasPolynomial poly2)
        {
            CasPolynomial res = new CasPolynomial();

            foreach (var t1 in poly1.Terms)
            {
                foreach (var t2 in poly2.Terms)
                {
                    res.Terms.Add(CasTerm.TermProduct(t1, t2));
                }
            }
            res.Simplify();
            return(res);
        }
        public static CasPolynomial PolySum(CasPolynomial poly1, CasPolynomial poly2)
        {
            CasPolynomial res = new CasPolynomial();

            foreach (var t in poly1.Terms)
            {
                res.Terms.Add(t);
            }
            foreach (var t in poly2.Terms)
            {
                res.Terms.Add(t);
            }
            res.Simplify();
            return(res);
        }