Lecture for ECE 175                               David MacQuigg 5/1/08
Using C in the Real World

C is an excellent foundation for freshman computer engineers and scientists, but currently, C is not being used much in later classes.  One way it could be very useful is in conjuction with a high-level language.  The high-level language provides the overall framwork for a solution, and C provides the fast, efficient code that may be needed at "bottlenecks" where the high-level language is too slow.

The example in this lecture is computation of Mandelbrot images.  We have a simple program written in Python to compute these images and display them using a graphics package we downloaded from the Internet.  The only problem is it runs way too slow.  Python has a nice interface for adding C-code inline, however.  Replacing a few lines of Python with C allows us to speed the generation of these images by a factor of 100.

Mandel_zoom_00
- speed of computation is important, 2500 x 2000 pixels
- zoom in on "seahorse valley"

Mandel_zoom_14  Julia Island
- magnification 60 billion!

Background on Languages
- languages poster
- progression of languages              1     2
  - domain-specific (FORTRAN, COBOL)
  - general-purpose, high-level (C)
    - one step above assembler
    - problem was complexity, one big pile of data
  - object-oriented (C++)
    - data now contained within independent objects
  - human oriented (Java, Python)
    - garbage collection
    - dynamic typing

Links to tools and further reading

HW Problem
- docstrings
- doctests, unit testing, Test-Driven Design (TDD)

pydemo.py                       demo2
- everything is an "object"
- yes, even a simple integer has a lot of moving parts !!

mandel_weave.py
- compare versions of getpts
- C 100X faster than Python

QnA - questions from students
- python-variables.htm
- dynamic_typing.txt
- mutable_args.py
- calling_methods.py