Second partial derivative test

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  • เผยแพร่เมื่อ 27 ธ.ค. 2024

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  • @abaundwal
    @abaundwal 4 ปีที่แล้ว +45

    This man is a lifesaver. I'm almost in tears. :')

    • @rahuldutta9303
      @rahuldutta9303 3 ปีที่แล้ว +2

      interesting surname u got there sir.just a rearrangement of one letter and we will get something even more interesting,no offense tho

    • @mohitpandey4655
      @mohitpandey4655 2 ปีที่แล้ว

      @@rahuldutta9303 oooh bhai 😂😂😂😂

  • @RSA_Shock
    @RSA_Shock 2 ปีที่แล้ว +10

    You and Sal khan need to get the noble peace prize for the amount of good you have done for the world

  • @ayushsingh-ib9nu
    @ayushsingh-ib9nu 5 ปีที่แล้ว +13

    Using a graph really helps. Thanks for the efforts

  • @jvcmarc
    @jvcmarc 6 ปีที่แล้ว +48

    isn't that test formula the determinant of the Hessian matrix

    • @TheLeontheking
      @TheLeontheking 5 ปีที่แล้ว +9

      scrolled to the comments to look for such a comment.. great how it all comes together!

    • @anonymous_4276
      @anonymous_4276 3 ปีที่แล้ว +4

      Hessian is the analogue of the second derivative for a function with multiple inputs and one output. The gradient is the analogue of the first derivative in this case. Move along any direction [dX]=[dx,dy], the change in function value will be gradient.[dx,dy] (dot product of gradient with [dx,dy]. Similarly, the change in this change (of the output) as we move along [dx,dy] will [dX(transpose)][Hessian][dX] (here we are doing matrix multiplication). That is basically the reason that formula shows up.

  • @niharikatasnim939
    @niharikatasnim939 ปีที่แล้ว +3

    But why are we subtracting fxy^2? What's the significance of this term? What does it mean geometrically?

  • @leytonzhang5607
    @leytonzhang5607 5 ปีที่แล้ว +5

    wow that is so freakin intuitive.. Grant. You are nutz.

  • @SohamChakraborty42069
    @SohamChakraborty42069 4 ปีที่แล้ว +9

    Isn't that the Hessian determinant in expanded form?

    • @Ben-dm8fi
      @Ben-dm8fi 4 หลายเดือนก่อน

      Yes it’s the determinant of the hessian matrix of the second partial derivatives. Easier to explain like this bc many people don’t know the hessian at this point in their math careers

  • @Ryannocerous
    @Ryannocerous 7 ปีที่แล้ว +4

    Great job, Very intuitive.

  • @Chino50863486
    @Chino50863486 7 ปีที่แล้ว +2

    what should we do when we get the special case of 0?

  • @snehamoypatra9786
    @snehamoypatra9786 4 ปีที่แล้ว +3

    Why scientist always hide the beauty. let make mathematics understandable for all people. what a amazing teacher you are

  • @a.fleischbender7681
    @a.fleischbender7681 3 ปีที่แล้ว

    Love you Grant

  • @debjyotichattopadhyay6679
    @debjyotichattopadhyay6679 6 ปีที่แล้ว +1

    Really nice ....deserve more views

  • @ahmedezzat687
    @ahmedezzat687 ปีที่แล้ว

    are you the guy of "3brown 1blue" ? anyway you have explained it very well, thank you

  • @ramiz2999
    @ramiz2999 3 ปีที่แล้ว

    Thank you for the video. I have a question: why ∂/∂x ( ∂z/dx) isn't ∂^2z/d^2x^2) or why ∂x (∂x) is ∂x^2 and not ∂^2x^2?

  • @elgatito00
    @elgatito00 4 ปีที่แล้ว

    Math God❣️

  • @stickAran
    @stickAran 4 ปีที่แล้ว

    6:52 MISTAKE DETECTED. its supposed to be fxy(xo,yo)^2 -fxx(xo,yo)*fyy(xo,yo)

  • @vladimirtomin8223
    @vladimirtomin8223 2 ปีที่แล้ว

    Without watching next video I will try to guess: when green part of the formula is bigger than red part of the formula it basically means that both half are in agreement and compliment direction of one another by multiplication

  • @ponderingprachiti
    @ponderingprachiti 3 ปีที่แล้ว

    eureka! it is the determinant of the Hessian matrix!

  • @kas8131
    @kas8131 8 หลายเดือนก่อน

    I’m watching this series just for fun

    • @mizan13926
      @mizan13926 หลายเดือนก่อน

      Watching to teach my gf😂

  • @hari8568
    @hari8568 7 ปีที่แล้ว +4

    Why does this seem like sorcery to me :(

    • @TheLeontheking
      @TheLeontheking 5 ปีที่แล้ว +8

      start with 3b1b's videos on single-variable-calculus, then start from the beginning of this series, take notes, and it will start to make sense for you :)
      Also i find pausing a video regularly, and reflecting on the steps taken, as well as which steps might lay ahead, very useful!

  • @wkdwoals
    @wkdwoals ปีที่แล้ว

    I love you Grant

  • @shwetupadhyay4822
    @shwetupadhyay4822 ปีที่แล้ว

    legend!!!!!!

  • @Goku17yen
    @Goku17yen 6 ปีที่แล้ว +1

    Graph looks like -x^2, if using both complex and Cartesian plane lmao

  • @JM-fo1te
    @JM-fo1te 8 ปีที่แล้ว +7

    :( too many mistakes.

  • @elgatito00
    @elgatito00 4 ปีที่แล้ว +1

    Math God❣️