Discussion of the Polynomial Class

Tom Kelliher, CS18

May 6, 1996

• Course Evaluation.
• Quiz.

The Polynomial Class

Polynomial Class Declaration:

#ifndef __POLYNOMIAL_H
#define __POLYNOMIAL_H

#include "list.h"

class Polynomial
{
 private:
   List L;
   int degree;

 public:
   Polynomial(void) : degree(-1) {}
   ~Polynomial() {}
   // Ensure that L's copy constructor is called.
   Polynomial(const Polynomial& b) : L(b.L) {}
   const Polynomial& operator=(const Polynomial& b) { L = b.L; }

   int Degree(void);
   int SetCoefficient(int exp, double co);
   int RetrieveCoefficient(int exp, double& co);
   void Print(void);
   const Polynomial operator+(const Polynomial& b) const;
   const Polynomial operator-(const Polynomial& b) const;
   const Polynomial operator*(const Polynomial& b) const;
};

#endif

Class Data Members

• L --- The list holding coefficient, exponent pairs. Manipulated using public member functions of underlying list class.
• degree --- The degree of the polynomial. Why initialize to -1? When might it be updated?

Class Member Functions

Might be useful to define some private member functions.

Recall the list member functions:

   List(void) : l(NULL) {}
   ~List();
   List(const List& b);
   const List& operator=(const List& b);
   int Insert(int exp, double co);
   int Retrieve(int exp, double& co);
   int Delete(int exp);
   void Print(void);   // For testing.

• Constructor, destructor, copy constructor, and assignment operator are taken care of.
• Degree() --- Obvious.
• SetCoefficient() --- Return 1 if successful, otherwise return 0. Consider this situation:

  Polynomial P;
  P.SetCoefficient(2, 1.33);
  P.SetCoefficient(2, 4.0);
  

  What list operations need to be performed?
• RetrieveCoefficient() --- Return 1 if Coefficient found, otherwise 0. Actual coefficient returned through co reference parameter.
• Print() --- Pretty print the polynomial:

  2.3X^3 + -6.3X + 7.1
  

• Addition --- Two ways of calling the function.

  Need a local polynomial.

  What should it return?

  How is addition performed?

  How the function should look:

  const Polynomial Polynomial::operator+(const Polynomial& b) const
  {
     Polynomial Sum;
  
     // Code for addition, using operations like:
     //    degree = (Degree() > b.Degree()) ? Degree() : b.Degree();
     //    check1 = Retrieve(i, co1);
     //    check2 = b.Retrieve(i, co2);
  
     return Sum;
  }
  

• Subtraction, Multiplication --- Just like addition, only different.

  How do we multiply?