Term::Term(int exponent, double scalar)
/*
Post: The Term is initialized with the given coefficient and exponent,
      or with default parameter values of 0.
*/
{
   degree = exponent;
   coefficient = scalar;
}


void Polynomial::print() const
/*
Post: The Polynomial is printed to cout.
*/
{
  Node *print_node = front;
  bool first_term = true;
  
  while (print_node != NULL) {
    Term &print_term = print_node->entry;
    if (first_term) {  //  In this case, suppress printing an initial '+'.
      first_term = false;
      if (print_term.coefficient < 0) cout << "- ";
    }
    else if (print_term.coefficient < 0) cout << " - ";
    else cout << " + ";
    double r = (print_term.coefficient >= 0)
      ? print_term.coefficient : -(print_term.coefficient);
    if (r != 1) cout << r;
    if (print_term.degree > 1) cout << " X^" << print_term.degree;
    if (print_term.degree == 1) cout << " X";
    if (r == 1 && print_term.degree == 0) cout << " 1";
    print_node = print_node->next;
  }
  if (first_term)
    cout << "0";  //  Print 0 for an empty Polynomial.
  cout << endl;
}


void Polynomial::read()
  /*
Post: The Polynomial is read from cin.
*/
{
  clear();
  double coefficient;
  int last_exponent, exponent;
  bool first_term = true;
  
  cout << "Enter the coefficients and exponents for the polynomial, "
       << "one pair per line.  Exponents must be in descending order." << endl
       << "Enter a coefficient of 0 or an exponent of 0 to terminate." << endl;
  
  do {
    cout << "coefficient? " << flush;
    cin  >> coefficient;
    if (coefficient != 0.0) {
      cout << "exponent? " << flush;
      cin  >> exponent;
      if ((!first_term && exponent >= last_exponent) || exponent < 0) {
	exponent = 0;
	
	cout << "Bad exponent: Polynomial terminates without its last term."
	     << endl;
      }
      else {
	Term new_term(exponent, coefficient);
	append(new_term);
	first_term = false;
      }
      last_exponent = exponent;
    }
  } while (coefficient != 0.0 && exponent != 0);
}


void Polynomial::equals_sum(Polynomial p, Polynomial q)
/*
Post: The Polynomial object is reset as the sum of the two parameters.
*/
{
   clear();
   while (!p.empty() || !q.empty()) {
     Term p_term, q_term;
     if (p.degree() > q.degree()) {
       p.serve_and_retrieve(p_term);
       append(p_term);
     }
     else if (q.degree() > p.degree()) {
       q.serve_and_retrieve(q_term);
       append(q_term);
     }
     else {
       p.serve_and_retrieve(p_term);
       q.serve_and_retrieve(q_term);
       if (p_term.coefficient + q_term.coefficient != 0) {
	 Term answer_term(p_term.degree,
			  p_term.coefficient + q_term.coefficient);
	 append(answer_term);
       }
     }
   }
}


int Polynomial::degree() const
/*
Post: If the Polynomial is identically 0, a result of -1 is returned.
      Otherwise the degree of the Polynomial is returned.
*/
{
  if (empty()) return -1;
  Term lead;
  retrieve(lead);
  return lead.degree;
}

/*************************************************************************/