Typos, comments, and corrections for computer project 2
25.04.11

Exercise1
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Q3: With "data" I mean the whitened data.

Exercise2
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In Eq (2), it should be \tilde{y}_m in the denominator

Q5, first sentence: Instead of "from the observations of \y and \s
alone", it should be "from the observations of \y alone". (You
apply ICA on y only)

Exercise3
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Note: The file is quite big. So loading may take a while.

In R, an efficient way to load the file is
X<-matrix(scan("mixed_images.txt",n=6*90000),6,90000,byrow="TRUE")

In matlab, "load mixed_images.txt" does the job.


Q3, step (d) of the algorithm: instead of "(1-tanh(y_i))^2" it
should be "1-tanh(y_i)^2". Only tanh is squared not 1-tanh.

Q3, step (h) : instead of "If the change in F is smaller than some small
threshold go back to step (c). Else return B and all the values of
F" it should be: 
"If the change in F is smaller than some small threshold, return B and
all the values of F. Else, go back to step (c)" You stop if the
objective does not increase any more.