Getting the "correct" (TM) answers in Qn 3..

[Subbarao Kambhampati <rao@asu.edu>]

Some of you complained that you are unable to get the tf/idf weights for 
your documents to agree with those
computed in the example shown in the class.

 It turns out that the example in the class uses

  -- 1. does not normalize the term frequency (so it is 24 for t1 in d1, 
not 1)
  -- 2.  uses natural logarithms (base e) for computing IDF

with that, you do get the exact answers that are shown there; here is the 
proof by google calculator

http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=24*ln%2810%2F9%29

I will change the homework description with this clarification.

Rao

ps: Also, in the first question AXv  is supposed to stand for A 
matrix-multiplied with v.