# Overview
# function definitions
# tuple and array basics
# more on while loops

x = 2
def f1(price,rate):
    tax = price*rate
    return tax
# f1

#print f1(19.99,0.0875)
#print f1(9.99, 0.05)

x = 0
while x<10:
    print x
    x = x+1   #  x += 1
# end while
print x

print "---------"

# Fibonacci sequence: 1 1 2 3 5 8 13 21 34 ...
a = 1
b = 1
counter = 0
while b < 2**20:
    print b, "  ",
    (a,b) = (b,a+b)
    counter += 1
# while
print "counter is now ", counter

# 5! = 5*4*3*2*1
# 0! = 1

def factorial(n):  # compute n!
#    if n<0: exit("bad parameter")
    ax = 1  # accumlates running product
    while n>1:
        ax = ax * n
        n = n-1   # n-=1
    # while
    return ax
# factorial

print factorial(5)
print factorial(0)
#print factorial(-2)
        
# test if a number is a prime number: 2 3 5 7 11 13 17 ...
def isprime(n):
    if n==2: return True
    else:
        k = 2 #....
        answer = True
        while (k<= n/2 and answer==True):
            if n%k == 0: answer = False
            k = k+1
        #while
    #else
    return answer
# isprime

print isprime(10)
print isprime(2)
print isprime(19)