csci 5304
C S C I     5 3 0 4

Announcements

• Mon Dec. 2, 2019 -- YS
As I mentioned in class this morning, I will be away from Tuesday to the end of this week, to attend a conference. So Tuesday's office hours is cancelled. The exam will be handled by Jack. Sorry for any inconvenience this may cause.

• Nov 28, 2019. YS
Regarding Exam~3: As a review on Monday I will go over some of the question of the sample examples that are posted but not all. I am posting solutions in case you want to use these for reviewing.

• Nov 16, 2019. YS
Regarding HW5: I am getting questions regarding Question~1 of HW5. Recall that Householder gives you Projectors P1, P2, ... Pn such that A = P1 P2 ... Pn R. The matrices P1, P2, are not explicitly stored -- instead the script [A, bet]=HoQR(A) outputs a matrix that contains the v_i's (below the main diagonal of output A) and the beta_i's. You need the first n columns of P1 P2 ... Pn. You obtain this by applying P1 P2 ... Pn to the matrix Z = eye(m,n) = matrix of columns e1 e2 ... en. This will extract the first n columns of P1 P2 .. Pn as needed. Note that you will have to apply this in the order n, n-1, ,,, 1 !! (for k=n:-1:1 ...), so Q = P1 (P2 ( ... (Pn Z))) and R = triu(A(1:n,1:n)). The only thing left is to figure out how to apply Pj to a matrix (the matrix Z)... Again do not explicitly compute Pi which is an mxm matrix (this is computationally expensive). We saw in class how to unpack the vector vk and then apply Pk = I - bet(k) vk vk' to a vector. You can do the same thing for matrices..

• Nov 13, 2019. YS
The following graph shows how everyone is doing so far in the class. [every student is represented by a small circle.]

• Nov 13, 2019. YS
Here are the stats for HW4:
``` mean       78.42   * mean   without zeros   92.50
median     92.00   * median without zeros   94.00
max       100.00   * min    without zeros   61.50
Number of As and A-s: 28
```

• Nov 13, 2019. YS
Here are the stats for Exam~2:
``` mean       78.76   * mean   without zeros   88.37
median     88.50   * median without zeros   90.00
max       102.00   * min    without zeros   60.00
```

• NovO4 31, 2019. YS
Clarifications for HW4. I have had a number of requests for clarifications for question 2.b. Specifically a few of you asked what is meant by orthogonality conditions. As was explained in class -- see also the illustration in Page 7-8 (of set 7) -- x* is solution of min || b - Fx||_2 if and only if b - F x* is orthogonal to the span of F. This is what is meant by the orthogonality condition. (The orthogonality condition leads to the normal equations.) In this particular question the hint essentially gives out the answer.. You just need to write that b - Ax is orthogonal to e and get some equation on the component xi which you then substitute. This will get rid of xi. ..

• Oct 31, 2019. YS
PLEASE NOTE: The data posted for HW4 question 2 (called 'dat4QR') has been reposted -- the previous one will cause a problem with cholR.. [reposted Oct.31, at ~9:00am and again at ~3:00pm ]

• Oct 23, 2019. YS
Change in office hours: Please note that I have to push my Monday hour up to 2:30pm (from 1:00pm) due to a department committee assignment. The Tuesday office hour remains the same. The new schedule is posted in the class web-site.

• Oct 8, 2019. YS
The first exam (MT1) has been graded. Here are the stats (base is 100):
``` mean       80.28   * mean   without zeros   87.93
median     90.00   * median without zeros   91.50
max       100.00   * min    without zeros   58.00
```
• Oct 8, 2019. YS
I have not yet posted the stats for HW1- Here they are:
``` mean       79.09   * mean   without zeros   90.95
median     92.00   * median without zeros   94.00
max       100.00   * min    without zeros   72.00
```
• Oct 2, 2019. YS
Please note: Question 6 of HW2 has been post-poned to HW3. It was replaced by a smaller problem left over from last time on nuclear norms.

• Sep. 30, 2019. YS
HW2 has been posted. Please note: For those who typeset their work with latex (or other word processors), you have the option of submitting your Homework by uploading it to Canvas. [PDF format please]

• Sep. 19, 2019. YS
There were questions on how to submit the homeworks. Please submit them in class. [beginning of class. Please do not interrupt lecture!] Handwritten ones are fine -- as long as they are readable.

• Sep. 18, 2019. YS
As I did not get to cover the Schatten norms in my last lecture, please ignore question 9-c of the Homework. I will have the same question (or a similar one) in HW2.

• Sep. 11, 2019. YS
Due to popular demand, I am starting to post solutions to the some of the exercises listed in the lecture notes. Look for ``Supplement ..." in the lectures notes pages. These may sometimes contain additional material such as clarifications, proofs, etc.

• Sep. 9, 2019. YS
I will be away Wednesday next week and so Jack (the TA) will be substituting for me for my lecture of Wednesday 18th. I will miss both office hours of next week. In order to make up for part of these, I will hold an extra office hour at the end of this week - namely Friday at 1:00pm [Need to leave at 2:00pm sharp.] Sorry if this causes any issues. I will also be available for a short while after lecture on Monday (16th) -- feel free to drop by my office if you have any questions.

• Aug. 15, 2019. YS
Welcome to csci5304.