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### Exercise 2, Problem 4

Verfasst: **28. Mai 2011 19:20**

von **Stumpf.Alex**

Hello,

Is there a litte mistake in the task description?

...you can sample from each of the six directions independently. ...

I just understand the full task, that we should generate six random samples for six faces from our given dirstribution and we should consider 20 bases, alright? So we have to draw for each sample from 20 (and not 6) directions or have i understood the task wrong?

greetings

### Re: Exercise 2, Problem 4

Verfasst: **30. Mai 2011 11:19**

von **qgao**

Stumpf.Alex hat geschrieben:Hello,

I just understand the full task, that we should generate six random samples for six faces from our given dirstribution and we should consider 20 bases, alright? So we have to draw for each sample from 20 (and not 6) directions or have i understood the task wrong?

Sorry, this is a typo error. Your understanding is correct!

I will send an email to everyone. Thank you very much.

### Re: Exercise 2, Problem 4

Verfasst: **31. Mai 2011 12:22**

von **engee**

Hi,

The covariance matrix that we are calculating is 8064x8064. I am running into memory problem if I try to do an SVD on the matrix. Are we supposed to work with the covariance matrix for this problem the image matrix itself as with the last problem?

Thanks

### Re: Exercise 2, Problem 4

Verfasst: **31. Mai 2011 12:44**

von **qgao**

engee hat geschrieben:Hi,

The covariance matrix that we are calculating is 8064x8064. I am running into memory problem if I try to do an SVD on the matrix. Are we supposed to work with the covariance matrix for this problem the image matrix itself as with the last problem?

Thanks

You do not have to compute the whole covariance matrix, but use "economy model" of svd function as in problem 3.

In the slides of 5th class, you might find something helpful.