csci 2033
C S C I     2 0 3 3

Announcements

• April 26, 2018, YS Info on Final:
• The final will be on Friday May 11th from 8:00am to 10:00am.
• Unlike quizzes, you will be allowed one formula sheet (back-to-back) The sheet should have your name on it
• Final is comprehensive. You may get any question from on material seen from the beginning of the course.
• Here is a practice exam from a previous year (login required):
Final_S16.pdf (PDF file).
• Here is the solution for the practice exam from a previous year (login required):
Final_S16_sol.pdf (PDF file).
• Someone asked me if I could post all quizzes given in semester. Here they are
Quiz1A.pdf
Quiz2A.pdf
Quiz3A.pdf
Quiz4A.pdf
Quiz5A.pdf
Quiz6A.pdf
Quiz7A.pdf
Quiz8A.pdf

• May 3, 2018, YS HW4 was graded by Shashanka Ubaru for questions 1 to 4 and 6--7, and by Jungseok Hong for questions 5 and 8 -- 10. Here are the grading criteria used by Jungseok for his part:
```
Problem 5 (10 pts)
rref: 2pts
basis of col(A): 3 pts
basis of Nul(A): 3pts
rank(A): 2pts
minor error: -1 pts

Problem 8 (10 pts)
formulation: 3pts
Matlab: 3pts
Solution
-a1,a2,a3: 2pts
-population: 1pt for each (2018.25, 2050)

Problem 9 (10 pts)
(a): 2 pts
(b): 2 pts, diagonalization: 1 pt, unique: 1pt
(c): 2 pts, not using lambda^2: -1 pt
(d): 2pts, not using lambda+1: -1 pt
(e): 2pts

Problem 10 (10 pts)
Calculation: 5 pts
Approximation; 5pts

Problem 11 (5 pts)
SVD: 2 pts
Rank: 3 pts
```

• April 26, 2018, YS A note on QR: It was pointed out to me that the text book does something a little more complicated than what we did for the QR factorization. In particular there is no need to multiply A by Q^T to get R. It is strongly suggested to use the traditional way of doing it as is done in the notes - it is simpler (fewer operations) and cleaner. In order to explain this better I added a longer worked out example - sarting in page 15-13 of set 15 of the notes.. Set 15 of the lecture notes was just re-posted accordingly.

• April 26, 2018, YS Info on 8th Quiz:
The quiz will be on Wednesday May 2 -- This quiz will last 25mn instead of 20 [last 25 mn of class]. The quiz is closed books -- no documents allowed; no calculators or any other devices (laptops, cell-phones, ...).
Coverage: All quizzes cover everything seen prior to the quiz except the day of the quiz and the previous lecture. For the next quiz, this means everything seen until Friday April 27th (inclusive).
To practice for the quiz, do the practice exercises, relevant questions in homeworks, questions in lecture notes which you should review carefully. While you may have a question on anything seen so far, the emphasis will be on least-squares, the QR factorization, eigenvalues, ... (no SVD).
Recall: The extra-credit ('bonus') questions (if any) are usually harder and it is recommended that you answer them last after you answered all other questions.

• April 18, 2018, YS Clarifications on HW4
• As I mentioned today I am changing the due date to Friday April 27th. In addition, all of Question 11 is now treated as an extra-credit question .
• Question 7: one of you asked about the complexity of the calculation. For the first part you need to use the normal equations. For the second part, you will need to use matlab for doing the calculations.. Otherwise it gets messy.

• April 14, 2018, YS Info on 7th Quiz:
The quiz will be on Friday April 20th [last 20 mn of class]. The quiz is closed books -- no documents allowed; no calculators or any other devices (laptops, cell-phones, ...).
Coverage: All quizzes cover everything seen prior to the quiz except the day of the quiz (clearly) and the previous lecture. For the next quiz, this means everything seen until Monday April 16th (inclusive).
To practice for the quiz, do the practice exercises, relevant questions in homeworks, questions in lecture notes which you should review carefully. While you may have a question on anything seen so far, the emphasis will be on dimension, rank, bases, norms, orthogonality, least-squares, etc.
Recall: The extra-credit ('bonus') questions (if any) are usually harder and it is recommended that you answer them last after you answered all other questions.

• Apr 13, 2018, YS Quiz6:
Here are the stats for Quiz #6:
``` mean       17.95   * mean   without zeros   20.52
median     19.00   * median without zeros   20.00
max        32.00   * min    without zeros    7.00
```
The base was 30 (with 2 points of extra credit). The two graders for this quiz were Abhishek (Type A) and Noah (Type B). Please address any questions about grading to them first.

• April 10, 2018, YS Homework 4 has been posted -- Due April 25th. Please start early - you can do about 1/2 of the homework right away. For the rest you will need to wait until we cover the material in the coming weeks.

• April 10, 2018, YS Homework 3 was graded. Here are the stats (out of a max of 100 + 5 extra points)
``` mean       76.33   * mean   without zeros   82.93
median     85.50   * median without zeros   86.00
max       105.00   * min    without zeros   27.00
```
The graders were Jessica for question 2 and questions 7 to 10, and Jungseok for question 1 and questions 3 to 6.
Here is the grading rubric for the questions graded by Jessica rubric questions 2 and 7--10
Here is the grading rubric for the questions graded by Jeonseok rubric questions 1 and 3--6

• April 6, 2018, YS A few people handed in ``additions'' to the homework [a single page] well after the due time. Normally, we should not accept these but I have allowed the practice. This is very disruptive [the TAs need to find the HW, add the page in, make sure it does not get lost in the various exchanges, etc.] So for the next homework I will institute a very simple penalty mechanism: penalty of -10 points for each page submitted late [a few hours late at the maximum]

• April 6, 2018, YS Interesting reading: (on the origin of least-squares)
Gauss and the discovery of Ceres

• April 2, 2018, YS Info on 6th Quiz:
The quiz will be on Monday April 9th [last 20 mn of class]. The quiz is closed books -- no documents allowed; no calculators or any other devices (laptops, cell-phones, ...).
Coverage: All quizzes cover everything seen prior to the quiz except the day of the quiz (clearly) and the previous lecture. For the next quiz, this means everything seen until April 4th (inclusive).
To practice for the quiz, do the practice exercises, relevant questions in homeworks, questions in lecture notes which you should review carefully. While you may have a question on anything seen so far, the emphasis will be vector spaces and subspaces, null spaces and column spaces, linear dependence/independence, dimension/rank, rank+nullity theorem, etc.
Also note: The extra-credit ('bonus') questions (if any) are usually harder and it is recommended that you answer them last after you answered all other questions. Apr 2, 2018, YS Change of office hours:
Please take note: My (Friday) April 6th office hour is cancelled. It is replaced by an office hour Monday April 2nd at the same time (1:00pm -- 2:00pm). This change is only for this week.

• Mar 30, 2018, YS Quiz5:
Quiz5 was graded. Here are the stats:
``` mean       21.89   * mean   without zeros   24.02
median     25.00   * median without zeros   25.50
max        33.00   * min    without zeros    8.00
```
The base was 30 (with 3 points of extra credit). The two graders for this quiz were Jessica (Type B) and Noah (Type A). Please address questions to them first.

• Mar 26th, 2018, YS Clarifications for HW3:
• In questions 2 and 4 `page 6-8' of notes refers to page number 6-8 of set 6 of notes and `page 10-12 of notes' refers to page number 10-12 of set 10 of notes.

• Mar 24, 2018, YS Please note: Due to travel my office hour of (Thursday) March 29th is cancelled. I will be available on Friday March 30.

• Mar 22, 2018, YS Info on 5th Quiz:
The quiz will be on March 28th [last 20 mn of class]. The quiz is closed books -- no documents allowed; no calculators or any other devices (laptops, cell-phones, ...).
Coverage: All quizzes cover everything seen prior to the quiz except the day of the quiz (clearly) and the previous lecture. For the next quiz, this means everything seen until Friday March 23.
To practice for the quiz, do the practice exercises, relevant questions in homeworks, questions in lecture notes which you should review carefully. While you may have a question on anything seen so far, the emphasis will be on inverses, the LU factorization (how to compute it, how to use it), determinants (how to compute them, how to use them for areas volumes,etc.)
Also note: The extra-credit ('bonus') questions (if any) are usually harder and it is recommended that you answer them last after you answered all other questions.

• Mar 15, 2018, YS Quiz4:
Quiz4 was graded. Here are the stats:
``` mean       22.71   * mean   without zeros   26.04
median     26.00   * median without zeros   26.50
max        33.00   * min    without zeros   10.00
```
The base was 30 (with 3 points of extra credit). The two graders for this quiz were Abhishek (Type A) and Noah (Type B). Please address questions to them first.

• Mar 8, 2018, YS HW2: Grading
• Questions 1 to 4 were graded by Abhishek
Grades based on how much a person explained their solution, so some cases might vary based on what they did.
Weights are:
• Question 1: 2 points for correct plot of equation. 5 points for converting equation to transformed version. 5 points for changing that transformed version (the vector) into an equation. 3 points for the final equation.
• Question 2: 6 points for final matrix of transformation. 4 points for correct reasoning (I 2-3 points off if students just used the matrix as given and only substituted the value of angle, i.e., 30 degrees).
• Question 3: In part A, 2 points each for correct response to whether unique solution and no solution is possible. 1 point for correct reasoning. In part B, 3 points for correct response and 2 points for reasoning.
• Question 4: 4 points for general solution using rref and writing down final set of equations. 8 points for providing proof for all four possible pairs that x1 + x2 = 10. 2 points for one particular solution.
MANY students forgot to prove the property in question 4, for which they got points struck off. Also MANY students in question one found just 2 points on line, transformed them and plotted the graph, because of which they got points struck off.
• Questions 5 to 7 were graded by Jungseok

• Mar 8, 2018, YS HW2:
HW2 has been graded. Here are the stats:
``` mean       75.49   * mean   without zeros   80.64
median     83.00   * median without zeros   84.00
max       100.00   * min    without zeros   33.00
```
Please note: The two graders for this assignment were Abhishek and Jungseok. More specific details on who graded which question, weights, grading criteria, ..., will be posted asap. For the sake of uniformity please address questions to the TAs first. Note also that I just posted the solution key.

• Mar 2, 2018, YS Change of office hours:
Please take note: The office hours of Jungseok Hong have changed. They are now Th: 9:00 -- 11:00am - in room KH 2-246 (location has also changed).

• Mar 2, 2018, YS A note on office hours:
When you come to office hours please be considerate to other students who are waiting.. They also need help.. If you sit in the chairs in my office then do not over-extend your stay. What is not acceptable is when someone comes without having even attempted to do a given question (matlab) and essentially starts doing it in my office asking question after question... while other students do not get a chance to ask a quick question for a minor clarification. To remedy this, I will accept walk ins to my office any time provided the question is *very* quick. This could be helpful around quizzes/homeworks.

• Mar 1, 2018, YS Info on 4th Quiz:
The quiz will be on March 7th [last 20 mn of class]. The quiz is closed books -- no documents allowed; no calculators or any other devices (laptops, cell-phones, ...).
Coverage: From now on all quizzes cover everything seen prior to the quiz except the day of the quiz (clearly) and the previous lecture. For the next quiz, this means everything seen until Friday March 2nd. This is essentially all of Lecture notes until set number 8.
To practice for the quiz, do the practice exercises, relevant questions in homeworks, questions in lecture notes which you should review carefully. There may be more questions on linear dependence.

• Feb 27, 2018, YS Regarding HW2: For question 7, use delta = 0.9 as in class. The HW has been reposted with this addition./

• Feb 16, 2018, YS Info on 3rd Quiz:
The quiz will be on Friday Feb 23 [last 20 mn of class]. The quiz is closed books -- no documents allowed; no calculators or any other devices (laptops, cell-phones, ...).
Coverage: everything seen until Lecture of Feb 20th -- this means up to lecture note # 7 - up to Page 7-17 of the notes. [no questions on what comes after page 7-17].
To practice for the quiz, do the practice exercises, relevant questions in homeworks, questions in lecture notes which you should review carefully. There may be more questions on linear dependence.

• Feb 14, 2018, YS HW1 was graded by Jungseok and Noah [they graded half of the homeworks each]. Please address questions to any one of them.

• Feb 6, 2018, YS Info on 2nd Quiz:
The quiz will be on Mon Feb 12 [last 20 mn of class]. The quiz is closed books -- no documents allowed; no calculators or any other devices (laptops, cell-phones, ...).
Coverage: everything seen until Lecture of Feb 7th: this means up to lecture note # 5. You may have a *short* question on matlab this time.
To practice for the quiz, do the practice exercises, relevant questions in homework 1, questions in lecture notes which you should review carefully. For matlab: see specifically commands that manipulate rows/columns of matrices [as in Gaussian elimination].

• Feb 2, YS
Quiz1 has been graded [graders: Jessica Lee and Jungseok Hong]. It will be returned to you in your discussion section. The stats are as follows (base is 30):
``` mean       23.19   * mean   without zeros   25.62
median     26.00   * median without zeros   26.00
max        30.00   * min    without zeros   14.00
```
Common mistakes in Quiz~1
• Not swapping rows 1 and 2 in Question 2.
• Incorrect row operations in Question 3
• Some students changed rows but did not modify the b part in the same way.
• Errors in calculations

• Jan. 28, 2018, YS Regarding HW1 : There was an error in the data for Problem 7. The HW has been reposted with the corrected data shown in red [proportions of N-P-K should be [20-15-15 instead of 20-10-15].

• Jan. 25, 2018, YS Info about 1st Quiz:
The quiz will be on Wed. Jan. 31st. We will take the last 20mn of the class for this.
The quiz is closed books -- no documents allowed. Also: no calculators or any other devices (laptops, cell-phones, ...).
Coverage: everything seen until Lecture of Jan 24th: this means lecture notes 1, 2, and 3.
There will be no questions on matlab this time -- [I will make sure to include at least one in Quiz~2.]
A few of you asked about practice exercises - specifically for the quiz. I prefer not to do this because this would imply a specific type of question. I recommend just doing all the practice exercises seen so far [posted in HW page] + reviewing the notes carefully.

• Jan. 10, 2018, YS
The recitations on the first day of class (Tuesday Jan 16th) will take place. I asked the TAs to start covering matlab.

• Jan. 10, 2018, YS
Welcome to csci2033! This is the primary location of all announcements regarding the class.