Prof Yan--Min-->>hi all i am your tutor Bong
Prof Yan--Min-->>please feel free to ask me
Prof Yan--Min-->>by the way I don't know y my appearant name is Pro Yan Min
Siu Him--Lau>>u are Bong but not Yan Min?
Prof Yan--Min-->>yeah I am tutor Bong not Pro Yan Min!
Prof Yan--Min-->>this error will be corrected in next time
Chun Pong--Derek--Chow>>then where is Yan Min?
Prof Yan--Min-->> anyone finished reading the material?
Prof Yan--Min-->>he will not be there!
Prof Yan--Min-->>he just appear on Sat tutorial!
Chun Pong--Derek--Chow>>WHY?
Prof Yan--Min-->>if he be there,than y math department need to empoly me?
Chun Pong--Derek--Chow>>why can't we type chinese here?
Prof Yan--Min-->>i don't know!
Chun Pong--Derek--Chow>>It will be much better if we can type chinese to discuss the material...
Tsz Wai--Yan>>i think so
Siu Him--Lau>>can prof read chinese?
Chun Pong--Derek--Chow>>He had said he know chinese
Ka Wai--Chan>>Then that's OK
Prof Yan--Min-->>of course he know!
Ka Wai--Chan>>Does anybody have some maths. Q.s
Prof Yan--Min-->>I also want to ask this question!
Chun Pong--Derek--Chow>>i would like to know what's the use of the row echleon form?
Prof Yan--Min-->>row echleon form can reduce the augmented matrix to the simplest appearance
Prof Yan--Min-->>and with this simplest form ,we can easily to find out the answer of the system of equation
Chun Pong--Derek--Chow>>but.....has the form (VALUE?) of the augmented matrix changed?
Chun Pong--Derek--Chow>>i don't know much about matrices.....
Prof Yan--Min-->>value of matrix?u mean the answer for the system of equation?
Chun Pong--Derek--Chow>>i mean the "appearance" of the matrix
Prof Yan--Min-->>do u know that the system of equation can be represented by Ax=b?
Chun Pong--Derek--Chow>>YES
Prof Yan--Min-->>the appearance of course changed!
Ka Wai--Chan>>what does that mean?
Prof Yan--Min-->>the appearance of A change and the value of b also change but the value of x not!
Chun Pong--Derek--Chow>>i see.....
Siu Him--Lau>>is the shape of the row echelon form independent of the choices of row operations i dont understand the proof
Ka Wai--Chan>>Ok
Ka Wai--Chan>>
Prof Yan--Min-->>yeah the shape is independent of row operation
Hiu Nga--Cheung>>have anyone done the exercise of row echelon form
Prof Yan--Min-->>since the final shape of the augmented matrix determine the value of variables
Hiu Nga--Cheung>>the answer may have some problems
Prof Yan--Min-->>and if the shape is different than we will and difft answer for the same sys of eq
Prof Yan--Min-->>which one have mistake?
Chun Pong--Derek--Chow>>but ...will the coefficients inside the matrix the same if we perform different row operations?
Prof Yan--Min-->>sorry hoe to get there?
Siu Him--Lau>>where?
Prof Yan--Min-->>is the exercise on the web?
Chun Pong--Derek--Chow>>WHERE?
Siu Him--Lau>>yes
Siu Him--Lau>>http://algebra.math.ust.hk/linear_equation/04_echelon_form/exercise.shtml are u talking about this one?
Chun Pong--Derek--Chow>>where i can find it?
Alex Yiu>>which exercise?
Prof Yan--Min-->>but under the topic of row echelon form i can't see any exercise!
Chun Pong--Derek--Chow>>me too!
Siu Him--Lau>>the link is in part 4
Hau Wai--Hui>>i cann't go there now!
Prof Yan--Min-->>ok ic
Prof Yan--Min-->>the exercise is in the part 4
Chun Pong--Derek--Chow>>i found it
Prof Yan--Min-->>wait
Alex Yiu>>but in which question did you find the problem?There are many question in that exercise
Alex Yiu>>typo->questions
Siu Him--Lau>>what is the advertage of reduced row echelon form when compare with row echelon form ?
Alex Yiu>>it could give out the answer immediately, right?
Prof Yan--Min-->> is the original matrix1211
Prof Yan--Min-->> 2110
Prof Yan--Min-->>0310
Prof Yan--Min-->>3010
Prof Yan--Min-->>is that prob?
Prof Yan--Min-->>ic
Prof Yan--Min-->>then it's already the echelon form!
Hau Wai--Hui>>listen him said
Prof Yan--Min-->>please don't send private massage so that other people can know what we'r doing!
Chun Sum--Lau>>......
Alex Yiu>>please don't be too shy to post questions publicly. Your questions are the questions of others in most case
Hiu Nga--Cheung>>ok
Hiu Nga--Cheung>>is it reducedform
Prof Yan--Min-->>yes it's reduced since every pivot is 1
Hiu Nga--Cheung>>the entries are not all 0
Prof Yan--Min-->>we just talking about ex2 no 11 of row reduced form
Hiu Nga--Cheung>>the entries above the pivot
Hiu Nga--Cheung>>not all 0
Hiu Nga--Cheung>>i can see the private massage of others, why
Prof Yan--Min-->>ic
Prof Yan--Min-->>2 should be changed to 0
Hiu Nga--Cheung>>then am i right
Prof Yan--Min-->>yeah
Alex Yiu>>cheung, you said you can or can't?
Hiu Nga--Cheung>>what is identity matrix
Hiu Nga--Cheung>>can
Prof Yan--Min-->>100
Prof Yan--Min-->>010
Prof Yan--Min-->>001
Prof Yan--Min-->>is example of identity matrix
Hiu Nga--Cheung>>then oo1
Prof Yan--Min-->>all elements in the diagonal is 1
Alex Yiu>>the entries of the diagonal are 1 and others are 0
Prof Yan--Min-->>yes
Hiu Nga--Cheung>>then listen
Hiu Nga--Cheung>>001
Hiu Nga--Cheung>>010
Hiu Nga--Cheung>>100
Hiu Nga--Cheung>>is not identity
Hiu Nga--Cheung>>??
Prof Yan--Min-->>let your matrix be A
Prof Yan--Min-->>let
Prof Yan--Min-->>1
Prof Yan--Min-->>1
Prof Yan--Min-->>1
Prof Yan--Min-->>be a vector x
Prof Yan--Min-->>Ax not equal to x
Prof Yan--Min-->>so it's not identity
Alex Yiu>> but could i exchange row 1 and row 3
Prof Yan--Min-->>Ax=x if and only if A is identity matrix
Prof Yan--Min-->>u get confused
Hiu Nga--Cheung>>yes
Prof Yan--Min-->>we use matrix to due with the problem of sys of eq
Prof Yan--Min-->>in this case we can do row operation
Prof Yan--Min-->>but if we just consider matrix itself
Prof Yan--Min-->>after exchange of row they maybe different matrix
Alex Yiu>>ic,thx
Prof Yan--Min-->>for example
Prof Yan--Min-->>we represent the sys of eq as Ax=b
Prof Yan--Min-->>the row operation will change A and b
Prof Yan--Min-->>but not the value of x
Hiu Nga--Cheung>>the chat room should be improved
Prof Yan--Min-->> in what way?
Hiu Nga--Cheung>>it is difficult to follow the conversation
Prof Yan--Min-->>i think we should develope the habbit that we talk about question one by one
Prof Yan--Min-->>and
Prof Yan--Min-->>one who have just raise question should wait for while so that other people can raise question also
Prof Yan--Min-->>if no one ask question then one can continue to ask
Alex Yiu>>i agree. It would be much better if we post public questions and quote the name of the student in front of the message as well
Hiu Nga--Cheung>>can you expain identity matric again
Prof Yan--Min-->>Can you guys see the question raised by other people and their name?
Prof Yan--Min-->>I wonder if u not because i can
Chun Pong--Derek--Chow>>YES
Prof Yan--Min-->>Alex can't?
Prof Yan--Min-->>u want ask why
Prof Yan--Min-->>001
Prof Yan--Min-->>010
Prof Yan--Min-->>100
Prof Yan--Min-->>not identity?
Hiu Nga--Cheung>>yes
Prof Yan--Min-->>Cheung
Prof Yan--Min-->> because it is the definition
Prof Yan--Min-->>of identitiy matrix
Prof Yan--Min-->>all elements in the diagonal is 1
Prof Yan--Min-->>and other entries are 0
Hiu Nga--Cheung>>the diagnol must be this way:
Hiu Nga--Cheung>>*00
Hiu Nga--Cheung>>0*0
Hiu Nga--Cheung>>00*
Prof Yan--Min-->>yes
Hiu Nga--Cheung>>ok
Prof Yan--Min-->>the identity matrix in matrix is just like 1 in real number
Siu Him--Lau>>then what is the use of identity matrix?
Prof Yan--Min-->>i ask u what is the use of 1 in real number system?
Prof Yan--Min-->>every matrix "times" the identity matrix is equal to itself
Prof Yan--Min-->>ie
Prof Yan--Min-->>IA=AI=A
Prof Yan--Min-->>I is identity matrix
Prof Yan--Min-->>I is n*n matrix
Prof Yan--Min-->>A is any n*n matrix
Siu Him--Lau>>thx
Prof Yan--Min-->>identity matrix of course is a square matrix
Hiu Nga--Cheung>>no one have other questions?
Prof Yan--Min-->>by the way all of u are F.6?
Hiu Nga--Cheung>>i am
Shuk Fan--Chau>>me too
Prof Yan--Min-->>good!
Chun Pong--Derek--Chow>><===
Prof Yan--Min-->>i think u have same chinese name as me
Chun Pong--Derek--Chow>>of course~
Chun Pong--Derek--Chow>>can you suggest any reference book for us to study?
Prof Yan--Min-->>in fact we can study the linear algebra with approach of geometry
Prof Yan--Min-->>because anything can be seen is much more easy to understand
Prof Yan--Min-->>besides the text book u can borrow books that link linear algebra and geometry together.
Hiu Nga--Cheung>>we study matric in F.6 ,what's the difference between what we learn in school and this program
Prof Yan--Min-->>in later
Prof Yan--Min-->>
Prof Yan--Min-->>the syllabus of A-level just require u to do the computation
Prof Yan--Min-->>u just know some technique of computation
Chun Pong--Derek--Chow>>how much does this programme covers our pure maths syllabus?
Prof Yan--Min-->>matrix is the computational tool for linear algebra. what we learn in this course is the concepts and theory, which is much more than computation
Prof Yan--Min-->>A lot more than pure math syllabus. I guess anything starting from chapter 3 are pretty much not in high school math
Prof Yan--Min-->>is the real Pro Yan Min?
Prof Yan--Min-->>There seems to be some problem with set up. The real Prof Min Yan just entered conversation at 10:50
Prof Yan--Min-->>haha I see!
Chun Pong--Derek--Chow>>then who is who??
Prof Yan--Min-->>i am Bong
Prof Yan--Min-->>u cannot distinguish now
Chun Pong--Derek--Chow>>that's right...
Prof Yan--Min-->>Unfortunately you cannot tell from the name only. But it does not matter as far as discussing math is concerned
Prof Yan--Min-->>I will try to ask the technicians tomorrow to find out where the problem is
Prof Yan--Min-->>Any math problem?
Hiu Nga--Cheung>>no
Prof Yan--Min-->>Any nonmath problem?
Prof Yan--Min-->>also so name of student is doubled
Prof Yan--Min-->>not only Pro Yan Min
Prof Yan--Min-->>Are you happy with the pace of the program. Is four sections for the first chatting too much?
Prof Yan--Min-->>
Chun Pong--Derek--Chow>>not too fast, not too slow...
Siu Him--Lau>>not too much. there are not much Q posted
Prof Yan--Min-->>Have you seen these kinds of material before?
Hiu Nga--Cheung>>many new maths words to me
Shuk Fan--Chau>>i agree
Prof Yan--Min-->>But what about the contents?
Hiu Nga--Cheung>>it's ok
Prof Yan--Min-->>Have you looked at the exercises?
Hiu Nga--Cheung>>yes
Prof Yan--Min-->>Can you do all of them?
Hiu Nga--Cheung>>done most
Prof Yan--Min-->>Any difficulty?
Hiu Nga--Cheung>>not much
Siu Him--Lau>>some of them i just go to the answer
Prof Yan--Min-->>Have you read the later sections?
Chun Pong--Derek--Chow>>still now...
Chun Pong--Derek--Chow>>not
Prof Yan--Min-->>Well you show do as much as you can. You may feel the pace getting faster later on
Hiu Nga--Cheung>>it's better to have some eplaination of new word, like identity matric , next time
Prof Yan--Min-->>Yeah. Please send me e-mail or better, post to discussion board. I modify the text immediately.
Hiu Nga--Cheung>>ok,bye
Prof Yan--Min-->>How come only two students are talking to me. Comments from the others?
Chun Pong--Derek--Chow>>here~
Prof Yan--Min-->>OK. Anything interesting to say?
Chun Pong--Derek--Chow>>i haven't typed english in computer for a long time.....
Prof Yan--Min-->>What other math are you guys studying now?
Chun Pong--Derek--Chow>>pure maths...
Siu Him--Lau>>properbility of applied maths is crazy
Chun Pong--Derek--Chow>>change chem!
Prof Yan--Min-->>Yeah. Today is actually the first time I do on-line chatting. I used to think it stupid to talk by typing. What a slow way to talk to each other. Phone call is more efficient.
Siu Him--Lau>>it is much easier to discuss face to face
Prof Yan--Min-->>yes i also think so
Prof Yan--Min-->>Why is probability crazy?
Chun Pong--Derek--Chow>>chemistry is better...
Siu Him--Lau>>i dont know some Q in the text book
Prof Yan--Min-->>You mean Q on probability?
Siu Him--Lau>>yes. i dont have any idea on the answer
Prof Yan--Min-->>Do you understand the textbook itself?
Siu Him--Lau>>yes but maybe the Q is too difficult for me
Prof Yan--Min-->>Sometimes it may be author's fault. Perhaps the author could include more guidance. In fact, a good thing about this course is that the web material can be changed easily. If you do not like certain part. I can always try to change it. The textbook you have in high school is unfortunately fixed.
Siu Him--Lau>>i got problems on uniqueness. but i am busy on my homework now. i will ask them next time. Good bye everyone!~~~
Prof Yan--Min-->>It is getting late for me. If you have more Q. Please post to discussion board. You may also call my office phone.
Prof Yan--Min-->>Bye bye from real Prof Min Yan
Prof Yan--Min-->>Bye Bye From Bong
Chun Pong--Derek--Chow>>BYE BYE~
Shuk Fan--Chau>>gd bye!!!!!!!!!
Siu Him--Lau>>where is wilde
Siu Him--Lau>>see u tomorrow
Chun Pong--Derek--Chow>>alian abduction
Chun Pong--Derek--Chow>>?
Chun Pong--Derek--Chow>>bye everybody! pls find wilde!
Siu Him--Lau>>wilde~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~