At the end of today's class you should

KNOW:
how to create functions with "static"
how to name constants
a function should be commented with a contract and a purpose
programs are built by combining smaller computations into larger computations

BE ABLE TO:
create a function that performs an arithmetic calculation on its inputs
write a contract and a purpose for a function

Exercises:

0. Define a function called tip that will add a 15% tip to a given number. Write a contract and a purpose for your function. Then define a function called shareWithTip that computes the share of the cost of a pizza, including the cost of the tip (refer to your answer to yesterday's sample exam question). Write a contract and purpose for shareWithTip.

1. Define the function fahrenheitToCelsius, which consumes a Fahrenheit temperature and produces the Celsius equivalent. Use Google or Wikipedia to find the conversion formula.

2. Define the function dollarToYen, which consumes a number of dollars and produces a number of yen. Use the Google search "1 dollar = yen" to find the current conversion.

3. Define the function areaOfTriangle, which consumes the length of a triangle's side and the perpendicular height and produces the area. Use Google or Wikipedia to find the formula.

4. Define the function convert3, which consumes three digits, starting with the least significant (meaning right-most when written positionally) digit, and produces the corresponding number. So, convert3(1,2,3) should produces 321 and convert3(3,2,1) should produces 123.

5. Formulate the following expressions as functions:
 a) n^2 + 10
 b) (1/2)*n^2 + 20
 c) 2 - (1/n)
Determine their results for n = 2 and n = 9 by hand and with Java.

6. Utopia's tax accountants always use programs that compute income taxes even though the tax rate is a solid, never-changing 15%. Define the program tax, which determines the tax on the gross pay.

7. The local supermarket needs a program that can compute the value of a bag of coins. Define the program sum_coins. It consumes four numbers: the number of pennies, nickels, dimes, and quarters in the bag; it produces the amount of money in the bag. 

8. An old-style movie theater has a simple profit function. Each customer pays $5 per ticket. Every performance costs the theater $20, plus $.50 per attendee. Develop the function total_profit. It consumes the number of attendees (of a show) and produces how much income the attendees produce.