Rhea Section for ECE 608 Professor Ghafoor, Spring 2009

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Hamza Bin Sohail Office Hours: Tuesday & Thursday 4:30-5:30PM in EE306

Course Website



On the news.purdue.edu server: purdue.class.ece608

One way to access: SSH to a server at Purdue (ie expert.ics.purdue.edu) and type "lynx news.purdue.edu/purdue.class.ece608"

On Ubuntu, you can use the "Pan" newsreader.

  • "sudo apt-get install pan"
  • Set "news.purdue.edu" as the server. You do not need to enter login information.
  • Type "purdue.class.ece608" in the box in the upper-left of the screen.
  • After a delay (half a minute?) the newsgroup will appear in the left pane. You can right click the group to "subscribe".

Reviewed Algorithms


Area to post questions, set up study groups, etc.


Attempted solution for 4-4 part (d): $ T(n) = 3T(n/3+5)+n/2 $

We use the iteration method. Start with recursion tree:

  • Root node: $ \frac{n}{2} $
  • First level: $ 3\frac{\frac{n}{3}+5}{2} $
  • Second level: $ 9\frac{\frac{n}{3}+5}{4} $
  • ith level: $ \left(\frac{3}{2}\right)^i\left(\frac{n}{3}+5\right) $

Note: above is not correct

$ \left(\frac{n}{3}+5\right)\sum{\left(\frac{3}{2}\right)^i} $

Randomization (and prob 5.3-3)

As we've seen, Permute-With-All does not produce a uniform random permutation. Curious to see how it affects the distribution of permutations? Here's an experiment with the erroneous randomization algorithm: False randomize

In the solution given for this problem, their argument is that $ n^n $ is not a multiple of $ n! $ for $ n\ge 3 $. Intuitively, $ n! $ for $ n\ge 3 $ includes more than one prime factor, namely 2 and 3, whereas $ n^n $ of course has only one.

Prob 5.4-5

Is there an intuitive explanation as to why the nested summations in the solution evaluate to a "combination"?

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Abstract algebra continues the conceptual developments of linear algebra, on an even grander scale.

Dr. Paul Garrett