Eulers Theorem, Fermats Theorem and Discrete Logarithms (CSS322, L11, Y14)

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  • Опубліковано 18 жов 2024

КОМЕНТАРІ • 19

  • @orutrasalazar
    @orutrasalazar 8 років тому +2

    I just want to say thank you and that you have an excellent way of teaching. I learned more in this video than in my whole class and my final is tomorrow!

  • @SutraWasTaken
    @SutraWasTaken 9 років тому +2

    The title is misspelled, just a minor point. I am learning a lot, thanks. (Although I am watching on 2x or 3x speed most of the time. I personally think you can make the course slightly harder/faster/denser to make it more interesting!)

  • @joseluisfernandez5981
    @joseluisfernandez5981 7 років тому +2

    Good lecture. Thanks a lot!:

  • @scitwi9164
    @scitwi9164 7 років тому +2

    28:15 Why in the first form there is that additional requirement for `a` and `p` to be relatively prime, but there isn't such a requirement in the second form? Isn't it that the first form is just the second form divided by `a` on both sides?
    54:15 3^5 mod 7 is 5, not 2. And yes, we did that before, so this mistake shouldn't have happened :P Especially that it lasted on the board for 7 minutes and nobody spotted the error :P And you even hovered the mouse cursor over it several times when drawing the box around that row. You also told that there shouldn't be any repetitions in this row, while there clearly were: the 2 repeated twice (because of the error). So there were multiple occasions to spot the error.

    • @lewischeung868
      @lewischeung868 7 років тому

      Answering 28:15 for u, actually it is the same thing.
      On theorem (2),
      if 'a' is divisible by 'p', namely a=kp for some positive integer k
      then we have a^p=(kp)^p=0(=p=kp)=a
      then whether 'a' is divisible by 'p' or not means nothing from the second theorem.
      however, on theorem (1),
      if 'a' is divisible by 'p', namely a=kp for some positive integer k
      then we have a^p=(kp)^p=0 =/=1
      hence 'a' is not divisible by 'p' is important here

  • @michaelpound9891
    @michaelpound9891 8 років тому +2

    Thanks a lot for this, very informative. When you calculate the table of powers of a mod 7, am I right in thinking you can use (a mod n) x (b mod n) mod n = ab mod n as a shortcut to avoid using the calculator after you've calculated the first two columns?

    • @StevenGordonAU
      @StevenGordonAU  8 років тому

      +Michael Pound Yes, the laws of mod can be used to simplify calculations.

  • @erratic88
    @erratic88 9 років тому +1

    When you showed how a table was constructed for powers of 'a' mod 7, there were two entries of '2' in a row you stated as being a primitive root. Was one of those supposed to be a '5' or was I misunderstanding what was meant by 'unique'?

    • @StevenGordonAU
      @StevenGordonAU  9 років тому +1

      +Ray Howard You are correct, that is a mistake. With a = 3, a^5 = 243 and 243 mod 7 = 5. 3 IS a primitive root in mod 7.

    • @erratic88
      @erratic88 9 років тому +1

      Thanks for confirming. Also, thanks for the video.

  • @spareyourbrain
    @spareyourbrain 6 років тому +1

    Hello sir
    On Euler theorem (2) say: "For positive integers a and n". Is the condition "co-prime" or "relatively prime" required? Or is it any a and n?

    • @sirajrais4122
      @sirajrais4122 6 років тому

      Hey if we wanna toeint of big value like 500 how can we find it??

  • @gyanganga247
    @gyanganga247 8 років тому

    thanks a lot for good advice to understood Euler theorem

  • @pilotnur4777
    @pilotnur4777 5 років тому

    bro.............you help me a lot many............infinite thanks love for you. Time [59:00- 1:01:00] is the best for me

  • @xaviergonzalez5652
    @xaviergonzalez5652 8 років тому

    outstanding!! thank you so much!

  • @syedmdabid7191
    @syedmdabid7191 4 роки тому

    By this theorem, find out the total no. Of digit of 4697 to the power 789475 in 4 second ?

  • @mmm763
    @mmm763 5 років тому

    a^(phi(n)) mod n = a
    Do "a" need to be smaller than "n"?

  • @user-uh2ez9uz3g
    @user-uh2ez9uz3g 8 років тому

    what about 3^7605%7=6