1. Week 4 : Function with parameters and return values

2. Today’s Topic  Variables  Interacting with a user’s input (function ‘raw_input’)  Function with parameters and return values

3. Practices  Teach Hubo How to Add  Addition  Being Mathematician  being Euclid  being Edmund Gunter (#1)  being Gunter Reloaded (#2)  being Gunter Reloaded (#3)  Caution: Save your python files in C:/cs101/ and clear the directory when you complete the tasks.

4. Task | Variables – Addition Teach Hubo how to add two numbers There are two numbers in base 10 on the row 1 and 2 Add two numbers and put the result on the row 1 ※ Your program must work for add1.wld, add2.wld, and add34.wld ※ Hint : Use variables in order to remember two numbers add34.wld Before After add1.wld add2.wld

5. Task | being Euclid  Given three numbers a, b, and c, it is possible to form a triangle whose sides have length a, b, and c if and only if the triangle inequality holds. That is, every side must be shorter than the sum of the other two sides.

6. Task | being Euclid (cont’d)  Define a function ‘is_triangle()’ which  takes three float values (three parameters)  returns True or False depending on whether three values can form a triangle  Write a program which 1.asks the user to enter three float values 2.evaluates input numbers using function ‘is_triangle()’ 3.outputs YES or NO depending on the result of ‘is_triangle()’ function ※ Hint: You must call the function ‘raw_input’ and use ‘print’ outside of the function.  Sample input and output Side a: 2.3 Side b: 4.3 Side c: 5.6 YES

7. Task | being Edmund Gunter  Modify the following program to ask the user for the number of steps (instead of using 41 fixed steps). import math sin = math.sin pi = math.pi for i in range(41): x = float(i) / 40.0 * 2 * pi print sin(x) for i in range(3) print i Hint : Try this to find out. Note : By the way, why 41 in range?

8. Task | being Gunter Reloaded #2  Change the program to print a nice curve like this: 40 80

9.  Change the program to print a curve like this instead: Hint : Convert the result of ‘sin’ function to a number of blank and a single asterisk (e.g.) print “ “ * 5 + “!!” !! Task | being Gunter Reloaded #3 5

10. Any Questions?