History

Inthe 1950's, FORTRAN and Cobol were among the first "high level" languages to be developed. Until then, programmers had used machine languages and assembly languages that were specific to each processor. The language C did not appear until the 1970's.

for loops 

  for count in range(10):
      print count
This is shorthand for 
  count = 0
  while count < 10:
      print count
      count += 1
You can also use other lists or strings as the index set 
  for ch in 'abccba':
      if ch in 'aeiou':
         print ch, ' is a vowel'

breaking out of a whle loop

A loop is like a rotary with a single entry point, but you don't have to exit at the same point. 
   sum = 0.0
   count = 0
   num = input("Enter a number ")
   while num != -1:
      sum += num
      count += 1
      num = input("Enter a number ")
   av = sum/count
another scheme is 
   while True:
      num = input("Enter a number ")
      if num == -1:
         break
      sum += num
      count += 1
   av = sum/count

Coercing ints and strings into boolean 

 
   while 1
   while 'on'

Pythagorean triples

3, 4, 5 is a Pythagorean triple. How do we enumerate them?
Using while loops? Using for loops?

Functions

You have already used functions: random.randint(1, 6), math.sin(x), input("Enter something"), float(sum), open(filename)
You can expand the language by writing new functions. For example, minOfThree(a,b). 
  def minOfThree(a, b):
     < block of statements>
def takes your block of code and makes it into a function that you can call

Testing your code

See week3TestMin.py
It is a good practice to generate tests for functions and (later) modules before you write them.

Recursion

Let's compute factorial: A factorial function can be written that calls itself. It behaves as if it cloned itself.