Computational Physics Spring 1996

W. Christian

Homework

Building a User Interface	First Program
Regression	Pendulum ODE
Laplace's Equation	Complex Class
Final Project Poster Session on May 7

Student Solutions to Homework

	Linear LINEAR plots two linear equations and calculates their intersection. The program does this simple job very well. Beginning Delphi students should study the interface. It is very clean, attractive and easy to use. Notice that the program starts with realistic data in the input fields. Notice that the graph scales itself in order to put the intersection near the center of the screen.
Linear.ZIP Source code.	Linear.EXE (472K) Run the application.
	Regress REGRESS does a linear regression for a set of (x,y) data points. Datum are displayed in both graphical and text format. This was the first student exercise that had an about box and help available from a main menu. Would anyone like to add the ability to edit or remove a single datum?
Regress.ZIP Source code.	Regress.EXE (472K) Run the application.
	Pendulum Solves the ODE for a pendulum using various numerical methods. The animations is a nice feature although some graphics cards have trouble with this drawing operation and leave stray dots on on the screen.
Pendulum.ZIP Source code.	Pendulum.EXE (472K) Run the application.
	Temperature This project and the following project both solve Laplace's equation but the two student authors come up with quite different user interfaces. These programs are not fast since they use a system timer for each calculation step but they do give a good introduction into how a finite difference method works for a two dimensional problem.
Temperature.ZIP (212K) Source code.	Temperature.EXE (K) (718K) Run the application.
	Laplace Similar to the Temperature program above but with a different user interface. The legend for the contour scale is a nice touch.
Laplace.ZIP (213K) Source code.	Laplace.EXE (507K) Run the application.
	Complex This program tests the COMPLEX object class that was assigned for homework. Although there isn't much room for originality in this type of project, the program is easy to use, attractive, and tests all the class methods as expected.
Complex.ZIP (235K) Source code.	Complex.EXE (600K) Run the application.

How to Attack the Programming Exercises.

THINK

Try and do the problem using pencil and paper using a very special case or a small amount of data. This will help you understand the algorithm and generate values that you can use to debug the program.

ORGANIZE

• Create a separate directory for each programming project.
• Create a new project in Delphi and save this project into the new directory using descriptive file names.

BUILD A SHELL

• Draw the graphical user interface, GUI.
• Set the initial values for important variables.
• Write Do-Nothing subroutines that show your program's structure. Add a comment to every subroutine declaration to tell yourself what this subroutine will eventually do.
• See if the shell will compile.
• Save your work and make a second backup on floppy disk.

MAKE IT WORK

• Add the algorithms to make the program do the required calculations. Do the simplest case first.
• Add documentation as you go along explaining what you think the code does.
• Use the debug features of Delphi such as breakpoints, single step, and trace to find bugs.
• Learn how to use the online help!
• Check your results against know solutions.

MAKE IT USEFUL

• Add menus, about boxes, and secondary forms to give the user control.
• Have a friend test the program and watch what they do without any intervention on your part. Can a new user figure out how to operate the program? Do they like how it looks?
• Try and crash the program. Put in crazy values. Trap for both mathematical singularities and non-physical input.

LEARN FROM OTHERS

• Read the book. You may not understand everything the author is saying but you can certainly copy source fragments such as how to create a dialog box.
• Look at the sample code that I have posted on the WWW including solutions to previous problems.
• Come by and ask questions.

THE GOLDEN RULES