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Basis and Dimension 

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MIT 18.06SC Linear Algebra, Fall 2011
View the complete course: ocw.mit.edu/18-06SCF11
Instructor: Ana Rita Pires
A teaching assistant works through a problem on basis and dimension.
License: Creative Commons BY-NC-SA
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More courses at ocw.mit.edu

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24 июл 2018

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Комментарии : 47   
@sheikhshafayat6984
@sheikhshafayat6984 4 года назад
These MIT lectures are too good to be true. Thanks to all behind these videos.
@red_l6634
@red_l6634 7 месяцев назад
When you work with column vectors and perform row operations on matrices, the operations mix the components within each vector. For example, when you add or subtract rows representing column vectors (like [x, y, z, w]), the operations combine elements from the same vector. This can lead to combinations like x + y within the same vector, which doesn't maintain the original components separately. However, when you use row vectors in row operations, these operations don't mix components of the same vector. Each row represents a different vector, and the operations performed on rows don't blend or combine elements within a single vector. you just add or subtract or exchange vectors, and it is fine. So , that's why you cannot use the final columns when you eliminate using column vectors. You do not perform linear operations between different vectors, rather you mix a vector with itself
@anonymousgawd..3047
@anonymousgawd..3047 7 месяцев назад
Thnx 🎉red ...good work it's a basic thought but yeah there should be clarity
@then-go
@then-go 3 месяца назад
Thank you so much for your explanation!
@AnupKumar-wk8ed
@AnupKumar-wk8ed 5 лет назад
Thanks a lot for showing the case of these vectors as columns. I had solved the matrix for pivots and chosen first three columns of the Echelon matrix as the basis. But clearly, as you pointed it out I was wrong. Awesome tutorial.
@bridge5189
@bridge5189 4 года назад
But, in the next lecture #10, at ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nHlE7EgJFds.html Prof Gilbert Strang says that basis is the PIVOT COLUMNS!!
@dHnd2j1u
@dHnd2j1u 4 года назад
​@@bridge5189 Actually, a few seconds before Prof Strang explains by saying "the pivot columns i'm interested in are columns of A, the ORIGINAL A" ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nHlE7EgJFds.html
@sachinbs3961
@sachinbs3961 3 года назад
@Indrajeet It is possible to pick the last columns if we performed column elimination. Then we would only have performed linear combinations of columns. Of-course then it would be same as writing the vectors as rows as doing row elimination which was the first method as explained in the video.
@NicolasAumar
@NicolasAumar Год назад
@@bridge5189 The basis could be the pivot columns of the initial matrix, not the pivot columns of the matrix after elimination.
@hoangduy500
@hoangduy500 Год назад
@@bridge5189 pivot columns here mean the position of the initial column, not the column after elimation.
@CodehanCodes
@CodehanCodes 5 лет назад
I just fell in love with this teacher ,you gave me such a great understanding
@bitstsunami9520
@bitstsunami9520 4 года назад
I think this girl and the Asian one are the best TA so far in any MIT ocw
@quirkyquester
@quirkyquester 4 года назад
Thank you Ana and MIT!
@lee_land_y69
@lee_land_y69 6 лет назад
thanks for pointing out about using the transpose matrix to solve the problem. that was exactly my question
@zhaopeter6532
@zhaopeter6532 6 лет назад
hi, do you know why they have same pivots (a matrix and its transpose)?
@samuelleung9930
@samuelleung9930 4 года назад
zhao peter it just happens to be the same. Or when you do rref, you will always get the same pivots :)
@biswabismitabag9017
@biswabismitabag9017 4 года назад
Thanks MIT for sharing such a great teacher and his teaching with the Whole World..A Learner From India..
@turokg1578
@turokg1578 Год назад
thanks a lot for the clarification at the end
@nerophon
@nerophon 5 лет назад
It would be good to know why you can use the rows of the echelon matrix when doing vectors-as-rows, but can't use the columns of the echelon matrix when doing vectors-as-columns. The fact is stated, and justification is given in terms of the example ("not enough numbers"). But the reason why the methods aren't symmetrical is not explained. I believe there ought to be a good geometric explanation for this, or at least something in terms of the definitions of the spaces.
@robertchu4092
@robertchu4092 5 лет назад
This is because columns in the echelon matrix are not formed by any linear combinations of the original columns. The process of creating echelon matrix is basically a series of row operations (i.e., new rows are formed by linear combinations of original and modified rows), which preserves linear independence of pivot rows (not pivot columns). That's why she said you may even use those original rows that correspond to the pivot rows to form the basis for that space.
@krishnkantswarnkar4735
@krishnkantswarnkar4735 5 лет назад
@@robertchu4092 Hey! thanks. I had the same doubt. This was a good explaination.
@harshadzade3971
@harshadzade3971 2 года назад
@@robertchu4092 This was helpful! Thanks!
@AkashRoy-do2dg
@AkashRoy-do2dg 4 месяца назад
as there are 5 column vectors and each vector belong to R^4(we can have almost 4 linearly independent vectors for R^4) so don't even need to check if they are dependent by doing gaussian elemination.
@vcbcricavenue2235
@vcbcricavenue2235 3 года назад
excellent way of teaching👏👏👏👏
@itsnotthattough7588
@itsnotthattough7588 2 месяца назад
Very clear. Thank you very much!
@yiyu9519
@yiyu9519 3 года назад
love this course
@kishoremandalapu133
@kishoremandalapu133 3 года назад
please confirm (1,1,-2,0,-1) row vector or column vector, while soling TA taken as Row Vector is it correct
@abhishekshinde9209
@abhishekshinde9209 3 года назад
Dont We take columns in basis?
@SHREYANSHPANDA_
@SHREYANSHPANDA_ 3 года назад
Can I solve it by finding the rref of the given matrix
@uvaishassan
@uvaishassan 3 года назад
So if I wrote the vectors as rows and did the elimination, I can directly use the final 3 rows (with pivots)?
@heyheyheyy5008
@heyheyheyy5008 3 года назад
Yep
@MrSnitsarenko
@MrSnitsarenko 4 года назад
great recite!
@zhiqiangzhao1267
@zhiqiangzhao1267 5 лет назад
thank you so much
@ivanzavaruev3021
@ivanzavaruev3021 Год назад
Thank you!
@sameerthor11
@sameerthor11 Год назад
Thankyou very much
@ashutoshtiwari4398
@ashutoshtiwari4398 5 лет назад
Why is that the elimination of column vectors changes the column space ( 7:06 ) but the elimination of row vectors doesn't change the space (4:40) ?
@ashutoshtiwari4398
@ashutoshtiwari4398 5 лет назад
I got the answer. Lec-10, 24:00. Row transformation on a matrix A dosen't change its row space but changes its column space.
@DeepakSingh-xt5io
@DeepakSingh-xt5io 5 лет назад
@@ashutoshtiwari4398 i was about to comment the same thing :)
@user-ks5wj6hz9x
@user-ks5wj6hz9x 4 года назад
@@ashutoshtiwari4398 thanks
@shaunwu3609
@shaunwu3609 4 года назад
Because you are performing the row operations on the column vectors, inevitably changing the column space. If you perform column operations on the column vectors, you would not be changing the column space. The column position of the leading ones after transposing the matrix and performing row operations would correspond to the row position of the original matrix.
@withoutpassid
@withoutpassid 7 дней назад
Why do those vectors become rows instead of columns of the matrix? Is it because they have to follow the rule of forming an mxn matrix where m < n? I'm confused.
@theultimate2345
@theultimate2345 5 дней назад
We can use any of them either as rows or columns as the rank of the resultant matrix is gonna be same and so the dimension of its vector space is same either way
@Upgradezz
@Upgradezz 3 года назад
Thank you :)
@cetintiryaki
@cetintiryaki 7 месяцев назад
Hey, I know this is a stupid question. What is the transpose of this universe?
@sohebsk2196
@sohebsk2196 2 месяца назад
"esrevinu " 😂
@shivajipatil1991
@shivajipatil1991 3 года назад
Vow....
@yys7916
@yys7916 Год назад
Thank you!