Part 3: Orthogonal Vectors

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  • เผยแพร่เมื่อ 30 มิ.ย. 2024
  • A Vision of Linear Algebra
    Instructor: Gilbert Strang
    View the complete course: ocw.mit.edu/2020-vision
    TH-cam Playlist: • A Vision of Linear Alg...
    Professor Strang describes in detail orthogonal vectors and matrices and subspaces. He explains Gram-Schmidt orthogonalization, as well as the Least Squares method for line fitting and non-square matrices.
    License: Creative Commons BY-NC-SA
    More information at ocw.mit.edu/terms
    More courses at ocw.mit.edu

ความคิดเห็น • 41

  • @mitocw
    @mitocw  4 ปีที่แล้ว +10

    For links to Professors Strang’s related courses on OCW, visit the Related Resources page on the full resource site: ocw.mit.edu/2020-vision.

  • @sarvasvarora
    @sarvasvarora 3 ปีที่แล้ว +36

    LMAOO he never forgets dissing Schmidt

  • @ramonmassoni9657
    @ramonmassoni9657 4 ปีที่แล้ว +40

    It's 2020 and Schmidt is still getting wrecked lmao

    • @echolee601
      @echolee601 4 ปีที่แล้ว

      Ramon Massoni 😂

    • @beoptimistic5853
      @beoptimistic5853 3 ปีที่แล้ว

      th-cam.com/video/XPCgGT9BlrQ/w-d-xo.html 👍💐💐

  • @inigom6400
    @inigom6400 4 ปีที่แล้ว +16

    Graham has the idea, I don't know how Schmidt got into it... 18:06 Nostalgia

    • @omersayli
      @omersayli 4 ปีที่แล้ว +1

      yes, it was in lectures too as far as I remember

  • @HuyDo-wl8su
    @HuyDo-wl8su 3 ปีที่แล้ว +6

    I've just found out he's 86 this year. Such a legend.

  • @maxwellsdaemon7
    @maxwellsdaemon7 4 ปีที่แล้ว +9

    This is the fourth video of the series I am watching. While I think I am familiar and comfortable with LA, I already learned some useful and interesting concepts and points of view from these lectures. BTW, this is how I imagine Mr. Rogers would teach LA, if Mr. Rogers were a math teacher.

    • @troychavez
      @troychavez 2 ปีที่แล้ว +1

      Professor Strang is by far an incredible person and an amazing professor of mathematics.

  • @TheWitness1001
    @TheWitness1001 2 ปีที่แล้ว

    I feel like watching Messi in his waning days when I am watching these videos of Strang. I used to watch his MIT videos back in 2010. We are blessed to still have you Pr. Strang.

  • @herambpatilofficial
    @herambpatilofficial 4 ปีที่แล้ว +6

    I just love MIT OCW,
    I request you, people, to make a playlist of organic chemistry...

  • @freeeagle6074
    @freeeagle6074 2 ปีที่แล้ว +1

    10:07 In mind, "Let me write something. OMG! Where is my blackboard?" Miss your moving pieces of blackboard up and down many times in one session of the lecture, dear Professor.

  • @milleskov6124
    @milleskov6124 3 ปีที่แล้ว

    Dear Gilbert. I adore you so much! Even when it seems i ought to use admire or to be infatuated by you, i stand by baby doll adoration for your straight out simple wonderful math explanations ❤️ ILU for teaching us. THANK YOU!

  • @taylorlorenztransormation3102
    @taylorlorenztransormation3102 3 ปีที่แล้ว +1

    Unbelievable commentary. I was watching the videos out of order and thinking to myself “this guy is unusually good.” Then I heard him say his name.

  • @echolee601
    @echolee601 4 ปีที่แล้ว +7

    The geometric illustration of least square is soooo cool👍👍

    • @uzizizu
      @uzizizu 3 ปีที่แล้ว +1

      watch The Mathematics of Machine Learning by Zach Star at 2m20s - that what cool explanation of least squares is.

    • @brendawilliams8062
      @brendawilliams8062 2 ปีที่แล้ว

      It appears that Egypt liked polar co ordinates

  • @maxwellsdaemon7
    @maxwellsdaemon7 4 ปีที่แล้ว +2

    Note that there is a subtle "mistake" on the slide titled "Orthogonal matrix" (around 6:10). An example was presented where Q is the 2D rotation matrix, with eigenvalues exp(+ or - i \theta). The argument presented showing that |\lambda^2|^2 = 1 is true if the complex conjugate is taken at the same time as the transpose (^T) operation and if ||Qx||^2 and ||x||^2 are non-zero, so that these can be canceled from both sides. For the eigenvalues of the 2D matrix Q, obviously \lambda^2|^2 = 1. But if the complex conjugate is not taken with the transpose operation, ||Qx||^2 and ||x||^2 CANNOT be canceled from both sides since ||x||^2 = 0 for the 2D matrix Q.

    • @Suryaeditz180
      @Suryaeditz180 3 ปีที่แล้ว

      Man u r so intelligent 🙄🙄🙄

  • @Tiara48z
    @Tiara48z 4 ปีที่แล้ว +2

    Can we please get a detailed answer key to some extent for (odd or even questions) for the new book expected in 2021. Even if it’s for purchase I would be willing to buy it. Detailed solutions help out tremendously especially in showing exactly why a question is done in such a way. Thank you!

    • @jayasri6764
      @jayasri6764 4 ปีที่แล้ว

      Detailed solutions are very bad for a math textbook (Since you can just skip having to think) .Hints are more preferable.

  • @thomasfisherson
    @thomasfisherson 4 ปีที่แล้ว +2

    This dude's the OG of linear algebra.

  • @vhscincent
    @vhscincent 4 ปีที่แล้ว

    A real master

  • @videofountain
    @videofountain 4 ปีที่แล้ว +1

    Animated, Paced and Clear presentation.

  • @DerekWoolverton
    @DerekWoolverton 3 ปีที่แล้ว +1

    The length of a vector (-1,2,2) at 4:20 would be the same as the length of a vector (1,2,2) which would be sqrt(11), not sqrt(9).

  • @pavanchandra5401
    @pavanchandra5401 4 ปีที่แล้ว

    Professor Strang, Can you explain the limitations of least squares? When will the error vector be significantly large enough that it would nullify the method itself?

    • @oblomist
      @oblomist 4 ปีที่แล้ว +1

      Here's my completely ignorant guess. Once 'e' becomes longer than 'p' the value of projection drops below 50%, as does your ability to predict x-hat.

  • @markspin4596
    @markspin4596 3 ปีที่แล้ว

    The Godfather of Matrices...

  • @brendawilliams8062
    @brendawilliams8062 2 ปีที่แล้ว

    Thankyou

  • @quitest4850
    @quitest4850 4 ปีที่แล้ว +1

    Linear Algebra review day8

  • @brandomiranda6703
    @brandomiranda6703 2 ปีที่แล้ว +1

    I love prof Strang, but I think the proof he presented is a great example of why (unfortunately) ppl don't like proofs. Yes it shows why things are true but I'd assume for most ppl it comes out of thin air. There is little motivation to how it would occur to someone how to do it. e.g. no motivation of how you'd even know in the first that orthogonal is a property to expect from symmetric. Even if we did expect it, how in a proof real ppl doing them think hmm I have this property transpose and I need to use it as a key step in the my proof...etc. It is just too magical without any motivation from how the result would be expect or the proof method itself would be expect. Just a random set of facts that worked. This is what I think has to change for ppl to stop hating proofs. Make them appealing to humans, rather than to computers. Where did they come from? Where did the technique used work? etc.
    It's not a math journal (even then I think the above should apply), it's a class room.

  • @brainstormingsharing1309
    @brainstormingsharing1309 3 ปีที่แล้ว +1

    👍👍👍👍👍👍👍👍👍

  • @NothingMaster
    @NothingMaster 3 ปีที่แล้ว +1

    Spring Theory?! 🤔

    • @avishek_paul
      @avishek_paul 3 ปีที่แล้ว

      Isn't it be string theory?

  • @cycman98
    @cycman98 4 ปีที่แล้ว

    Why in 2:54 there is Q * Q^t != I ?

    • @cycman98
      @cycman98 4 ปีที่แล้ว +1

      It does not have to be square matrix

    • @xinlongdu6316
      @xinlongdu6316 4 ปีที่แล้ว

      Because the rows are not orthogonal to each other

    • @yuchenzhao6411
      @yuchenzhao6411 4 ปีที่แล้ว

      We only call Q orthogonal matrix when Q is square because only when Q is square Q^t = Q^-1 (Q_transpose = Q_inverse)

    • @ABNER518
      @ABNER518 4 ปีที่แล้ว

      I saw that. The ortogonal proposition is: Q*Q_t=I or Q_t=Q_1. But the slide changed the position. Is It correct?