1. Algorithms and Flow Charts

2. Algorithms A procedure or formula for solving a problem.
Drawing a square in Netlogo

3. Representation of Algorithms
Desirable Features
Language independent
Unambiguous
Easy to understand
A standard---understood and known by many
Solution
Flow charts

4. Drawing a square
As a flow chart:

5. Using variables
More general?

6. Repetition

7. Repetition in Netlogo On the previous slide while ;; repeats forever
loop
repeat
;; repeats forever
pd loop [ fd 0.5 rt 1 ]
;; the turtle draws a circle
pd repeat 36 [ fd 1 rt 10 ]

8. Decision

9. Decision if else statement if statement [ ifelse (xcor > 0)
[ set color blue ]
[ set color red ] ]
[ if (xcor > 0)
[ set color blue ] ]

10. Procedures

11. Input and Output

12. Symbol Summary
These seven symbols are used the most:

13. The Bug Game Implemented in Netlogo; here is the file
Objective: pick up all the food and return home in the fewest moves

14. The Bug Game
Write the procedure go using the following instructions (each instruction is actually a procedure call):
turn-right
turn-left
move-forward dist (dist must be specified)
pickup-food
see-food (sets variables)
see-start (sets variables)
at-food (sets variables)
at-start (sets variables)