CSC 160 Fall 2008 - Homework 6
Assigned Oct 29, due WEDS Nov 5

Read Chapters 9-11 of the textbook (skipping the sections and exercises on Animations as well as Section 10.7).

Directions
  • Read these directions carefully before starting the assignment.
  • The assignment may be done alone or in pairs using the ideas in the Pair Programming article.
  • You cannot pair up with the same person more than once during the semester.
  • If you are doing the assignment in pairs, please submit only one set of files with both names on it.
  • Whenever defining a Scheme function, you must show all six steps of the Design Recipe introduced in Chapter 5.
  • If you are defining auxiliary functions, you need to show the 6 steps of the Design Recipe for each of the auxiliary functions, as well as the 6 steps of the Design Recipe for the main (or primary) function.
  • When writing a program, the name of the main (or primary) function is the name of the program. Use sensible names of your choice for auxiliary functions.
  • If an auxiliary function is not predefined, but you have seen it written before (e.g. in class, on a reading assignment, or on a previous programming assignment), just copy the function definition (no contract, skeleton, etc.) into the top of your Definitions Pane.
  • For the given exercise, to receive full credit, you must use at least one auxiliary function that is not predefined in DrScheme or any of the teachpacks. However, functions that we have written before (including area-of-disk and mirror-image) do count as auxiliary functions.
  • If you do not fully understand any of the directions above or the questions below, please e-mail me as soon as possible.


    The Assignment
    Exercise 9.3.5 from the textbook:
       The nation of Progressiva has a simple tax code. The tax you pay is your salary times the tax rate, and the tax rate is 0.5% per thousand dollars of salary. For example, if you make $40,000, your tax rate is 0.5 times 40, which is 20%, so you pay 20% of $40,000 which is $8,000. Develop a Scheme program to compute the net pay (i.e. pay after taxes) of a person with a given salary.
    [Hint: You'll probably need one or two auxiliary functions along with the net-pay function.]

    Extra Credit (10 points): Answer the following question in a comment at the bottom of your Definitions Pane:
       If the tax rate rises to 0.6% per thousand dollars of salary, what would you need to modify in your program to handle this change?


    Submitting your Assignment
    Please submit this assignment in a single Definitions Pane and a single Interactions Pane through Moodle. Points will be deducted for completing the assignment with multiple Definitions and/or Interactions Panes.

    Be sure to include your first and last name as a comment in the first line of both your Definitions Pane and Interactions Pane.

    The file name for the Definitions Pane needs to be "hw6[LastName]Def.scm" where:
  • [LastName] is replaced with your last name.
  • For example, if I were submitting this assignment, I would name the file "hw6WittensteinDef.scm".

    Similarly, the file name for the Interactions Pane needs to be "hw6[LastName]Int.scm". The Interactions Pane must include testing for EACH function.

    If these filenames are not used, points will be deducted from the assignment grade.


    Grading Contracts Purposes Examples Skeletons Inventories Definitions Function Re-Use Testing
    Exercise 9.3.5 /8 /6 /8 /6 /6 /40 /20 /6


    Last Modified: 11/2/08