Introductory Programming
Fall 2004

For next time:

1) Read Chapter 3 of "How to think..."

2) Start Homework 2

But don't spend more than two hours.


Debugging
---------

"The programmer, like the poet, works only slightly removed from pure
thought-stuff. He builds castles in the air, from air, creating by
exertion of the imagination. Few media of creation are so flexible, so
easy to polish and rework, so readily capable of realizing grand
conceptual structures. Yet the program construct, unlike the poet's
words, is real in the sense that it moves and works, producing visible
outputs separate from the construct itself. It prints results, draws
pictures, produces sounds, moves arms. The magic of myth and legend
has come true in our time. One types the correct incantation on a
keyboard, and a display screen comes to life, showing things that
never were nor could be. ... The computer resembles the magic of
legend in this respect, too. If one character, one pause, of the
incantation is not strictly in proper form, the magic doesn't
work. Human beings are not accustomed to being perfect, and few areas
of human activity demand it.

"Adjusting to the requirement for perfection is, I think, the most
difficult part of learning to program."

- F. Brooks ("The Mythical Man Month") 


Theorem: You have to get it exactly right.

Corollary #1: You have to read and understand the error message when
you get it wrong (so you should make lots of mistakes!).

Corollary #2: You have to develop an eye for detail.

Corollary #3: Practice!  Dewey: "knowing is a form of doing"

Corollary #4: The more sense it makes, the easier it is to spot errors.


Math functions
--------------

1) You have to import the math module.

In the book, I use

>>> import math
>>> math.sin(math.pi)

But it's probably easier to use

>>> from math import *
>>> sin(pi)

Some non-obvious math functions:

1) raising a number to a power

   either  x**y   or   pow(x,y)

2) raising e to a power

   exp(x)

3) logarithms

   log(x)    is the natural log
   log10(x)  is the log base 10


Vocabulary
----------

1) function call

2) argument

3) return value



Printer configuration: See Chapter 3 of the Olinux manual.