edge detection - compass

I have a homework "Write a compass (wit Kirsch template mask) filtering program using Matlab" but i don't know that how to do it. Could you help or hint for me?

[Image Analyst]

I don't even know what that is. Try these links:

http://www.mathworks.com/matlabcentral/answers/8626-how-do-i-get-help-on-homework-questions-on-matlab-answers

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer