CS 2005, B Term 1999
Data Structures and Programming Techniques
HW1 (due Nov. 5)

This page is located at http://www.cs.wpi.edu/~alvarez/CS2005/B99/HW1/


Your task for this assignment is to implement an abstract data type that represents polynomials, using arrays as the internal representation (in the private part of the class definition).

Polynomials are among the most commonly used functions in symbolic algebra systems. A polynomial is a finite sum of constant multiples of powers of a variable x, for example

f(x) = 3x2 + 5x   or   g(x) = -9x4 + x - 5.

The multipliers in front of the powers of x are called coefficients. The highest power for which the associated coefficient is nonzero is called the degree of the polynomial. The above examples have degrees 2 and 4 respectively.

Polynomials may be added and multiplied according to the usual rules for numbers. The sum of the two polynomials given above is

f(x) + g(x) = -9x4 + 3x2 + 6x - 5.

The product of the two polynomials has degree 6; it is

f(x)*g(x) = -27 x6 -45 x5 + 3 x3 -10 x2 -25 x

One can represent a polynomial as an array containing the coefficients of the polynomial. For example, if arrays of length 7 are used, then f and g would be represented by the arrays [0,5,3,0,0,0,0] and [-5,1,0,0,-9,0,0]) respectively, where the convention is that the coefficient of the k-th power is stored in the k-th position of the array. Since the degrees of different polynomials may be different, the arrays used should have a size that's larger than the highest degree needed.


  1. Fill in the private part of the class definition for SPoly that appears in the header file spoly.h, using fixed-size arrays to store the coefficients.
  2. In a separate file called spoly.cxx, implement the public member functions whose specifications appear in the header file. Such member functions include a constructor and a constant member function that returns the coefficient of a specified power for a given polynomial. You should also provide overloaded + and * operators that return the usual sum and product of two polynomials. These two operators are declared to be either friend functions of the SPoly class or ordinary non-member functions as shown in the header file.
  3. Write a test program spolytest.cxx that lets the user invoke each of the public member functions of the Polynomial class by selecting from a menu of clearly explained options displayed on the console output. For each menu option, the test program should prompt the user to input the desired values of the arguments for the member function corresponding to that option. For example, the test program should allow the user to input a polynomial by giving its coefficients using the standard console input stream. The function should then be invoked, and the result of its invocation should be displayed on the console output in some way. Details of the interface design are left to the discretion of the programmer / designer.
  4. Provide documentation for your code following the WPI CS documentation standard. Detailed g++ compiler command lines should be included. Your code must compile and link correctly using g++ on the CCC Unix machines when these command lines are used.
  5. Write a brief discussion of the merits and drawbacks of the array implementation of the SPoly class. Does the implementation successfully achieve the desired functionality as specified in the header file? What limitations does the fixed-size array representation impose on the resulting implementation?
  6. Use turnin to electronically submit all of your files addressing the above items before 5 pm on Friday Nov. 5, 1999.