How To Solve Recurrence Relations

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  • Опубліковано 12 лип 2019
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КОМЕНТАРІ • 91

  • @MemoryException
    @MemoryException Рік тому +47

    Even three years later you can be proud your video is helping a random guy from the internet struggling to understand recurrence solutions. Thanks for posting it. 😊

  • @sergiocobo6000
    @sergiocobo6000 5 місяців тому +4

    This is one of the best explanations, step-by-step, on how to solve recurrence equations using induction/back substitution. Fantastic job!!!

  • @ryujiyamasaki355
    @ryujiyamasaki355 Рік тому +1

    finally a video that made me understand this concept!!!

  • @reelwon3595
    @reelwon3595 4 роки тому +50

    Just got me from a 60 on this HW to a 100. Thank you sir.

    • @bransonkody3416
      @bransonkody3416 3 роки тому +1

      @Bruce Khalil yup, I have been using flixzone} for years myself :D

    • @caseikelenboom2921
      @caseikelenboom2921 Рік тому

      i hope you failed later lol lol lol #funny

  • @RobinD0903
    @RobinD0903 Рік тому +10

    at 8:53, instead of converting to 2 times the sum of numbers, you can convert it to k(k-1). This allows you to skip the entire summation substitution, and after finding k=n, you can get n^2 - n from that

    • @MemoryException
      @MemoryException Рік тому

      I’m going to try and understand that this weekend! Thanks for the tip.

    • @jamesbowen9347
      @jamesbowen9347 10 місяців тому +2

      Thanks for the insight. From my perspective the way Randerson presented the work flow was incredibly helpful. For someone who is new to this or hasn't had good instructors in the past, taking shortcuts too early makes things difficult. Showing an example of such an elementary summation gave me the intuition for future more complex problems. Thanks again for your comment on how to pick the low hanging fruit.

  • @nped5054
    @nped5054 2 роки тому +1

    This made so much sense, great video

  • @FlawlessYT66
    @FlawlessYT66 Рік тому

    bro king of explanation keep the great work

  • @Ali-up6sd
    @Ali-up6sd 3 місяці тому +1

    Beautifully explained!! Thank u so so much. Never understood this til now🎉

  • @themysteriousfox3767
    @themysteriousfox3767 29 днів тому

    This is phenomonel, thank you! Couldn't have asked for a better explaination.

  • @ranad2037
    @ranad2037 2 роки тому +1

    Thanks A LOT! you are a true life saver!

  • @Traffy_01
    @Traffy_01 2 роки тому +1

    Many thanks, is there anywhere to find more summation formulae you recommend?

  • @jayannamorsolo796
    @jayannamorsolo796 3 роки тому

    thank you, untag makaanswer ko sa exam hahahha

  • @mdrsoooow
    @mdrsoooow Рік тому

    BRO U ARE THE GOAT

  • @luwluwstarshyne
    @luwluwstarshyne 8 місяців тому

    Thank U 🙏 Mr. Randerson🙌

  • @PaulBoldyrev
    @PaulBoldyrev 2 роки тому +2

    Very clearly explained, thanks a bunch!

  • @edinaleckovic2269
    @edinaleckovic2269 Рік тому +5

    You absolutely killed the explanation on this video!!! Great job!! and you have been an immense help! Super glad I found this video!!

  • @davidshechtman4746
    @davidshechtman4746 2 роки тому +4

    So I have a factorization algorithm. It is a sieve. But it involves checking the sums of naturals greater than N (the number to be factored) for certain conditions. Because the sums of the natural numbers increase by the square and N increases linearly. Does that mean my algorithm is N P efficient? It works particularly well for numbers congruent to + or - 1 (mod 6) whose factors are roughly of equivalent magnitude ie. public key style security numbers. That is the sums necessary are likely in close proximity on the number line to N if N is relatively square (that is as far as its factors being similar magnitude). I do recreational thinking and am not a programmer. Certainly not with large integers in hex.🤪

  • @Mohammed-hg6kw
    @Mohammed-hg6kw 4 місяці тому +1

    Thanks for this amazing and fulfilling explanation... literally helped me a lot!

  • @kylemauter5468
    @kylemauter5468 4 роки тому +2

    thank god for this

  • @monicaj3878
    @monicaj3878 3 роки тому

    Randerson thank you so much!

  • @awful999
    @awful999 3 місяці тому

    if you define the a function f’(n) where f’(n) is the inverse of function f(n) you can subtract T(n-1) and then divide by 1 you will get f’(n) = O(n) if you take the anti derivative of this result you get f(n) = O(n^2)

  • @youtrip1037
    @youtrip1037 3 роки тому

    an = an-1 + 2n a0 = 2 , solve the recurring relation. whats the solution for this ? like closed formula .

  • @trestenpool9045
    @trestenpool9045 3 роки тому +1

    Excellent, thank you very much!!

  • @pouyahallaj4445
    @pouyahallaj4445 2 роки тому

    You are my hero! Thanka

  • @naifabdullah3465
    @naifabdullah3465 Рік тому +2

    I really like the way you explained this. Very helpful and easy to understand. Thank you so much for your time.

  • @antwanwimberly1729
    @antwanwimberly1729 3 місяці тому

    This is awesome!! Thank you my friend.

  • @manyhamy6330
    @manyhamy6330 Рік тому +3

    The title should be "How To Solve this one Recurrence Relation"

  • @bestmovies939
    @bestmovies939 3 роки тому

    Sir. What about when it is k+1?

  • @jellybean7613
    @jellybean7613 2 місяці тому +1

    Wow thank you sooo mucchh 😭😭
    Btw, just a question, will it be much better to use the
    2(k-1+k-2+...+1)
    Than
    k(k-1)
    I tried guessing the pattern myself and my simpleton brain got T(n) = T(n-k) + k(2n) - (k(k-1)) instead, now I'm wondering if using the summation would be better?

  • @digantamondal2397
    @digantamondal2397 4 роки тому

    Q.t(0)=2
    t(n)=3t(n-1)+n+2^n

  • @linpa
    @linpa Рік тому

    great explaination, thanks!

  • @TheArmita14
    @TheArmita14 День тому

    Thank you so much for your video, it really helped me out

  • @ilyasilyas6252
    @ilyasilyas6252 2 роки тому +1

    mannnnnnnnnnnn you're a real one bro!!!!!!!!!

  • @DigvijaySingh-zd9hq
    @DigvijaySingh-zd9hq 4 місяці тому +1

    This is really helpful video thanks Rand!

  • @vanessachow7313
    @vanessachow7313 3 роки тому +1

    amazing video, thanks so much!

    • @randerson112358
      @randerson112358  3 роки тому

      Thanks you for watching Vanessa, I'm glad you liked it!

  • @Eutropios
    @Eutropios 7 місяців тому

    When K = 3, why are you throwing in the non-T terms from the K = 2 iteration 2(2n)-2 instead of the non-T terms from the K = 1 iteration 2n?

  • @craigspencer2826
    @craigspencer2826 4 роки тому +3

    Great job! very informative

  • @lexikelsall3114
    @lexikelsall3114 3 роки тому +1

    So helpful, thank you!!

    • @randerson112358
      @randerson112358  3 роки тому

      Thanks Lexi, I appreciate it and I'm glad that the video was helpful.

  • @Aaron_Nie
    @Aaron_Nie Рік тому

    man you are my god

  • @Matthew-dd6kp
    @Matthew-dd6kp 11 місяців тому

    Thank you.

  • @bilalbayrakdar7100
    @bilalbayrakdar7100 3 роки тому +1

    Very well explanation thx bro, u r a savior

  • @Festival-sb2kf
    @Festival-sb2kf Рік тому

    Really nice, thank you!

  • @adarozer
    @adarozer 2 роки тому +1

    Thanks bro

  • @MemoryException
    @MemoryException Рік тому

    In the last step, what happens to the 2n squared and the minus sign to get n squared plus n?

    • @randerson112358
      @randerson112358  Рік тому +2

      In the previous step the equation simplifies to:
      2n^2 - n^2 + n
      From there we get:
      n^2 + n

    • @MemoryException
      @MemoryException Рік тому

      @@randerson112358 I was screwing up on basic algebra. These videos are great.

  • @jfnwenflkwn
    @jfnwenflkwn 2 місяці тому

    Thanks!!

  • @taelocalxo4264
    @taelocalxo4264 2 роки тому

    Why does my prof suck so bad that this concept was so easily explained by you, a random dude on youtube (in the best way), and he couldn’t even tell us what k meant

  • @Adam-xn9lt
    @Adam-xn9lt Рік тому

    Amazing.

  • @blacksurface7995
    @blacksurface7995 4 роки тому +1

    Very good 👍

  • @bestmovies939
    @bestmovies939 3 роки тому

    Thaks sir

  • @Furkan-yv5ew
    @Furkan-yv5ew 4 місяці тому

    Why is it called O(n^2) instead of Teta(n^2)? The only part i didn't understand.

  • @ilyasilyas6252
    @ilyasilyas6252 2 роки тому +1

    had to like and subscribe :)

  • @momoshikioot9177
    @momoshikioot9177 3 роки тому +1

    How did you go from ( n^2 + n ) to conclude its O (n^2)? Why is it not O (n^2 + n) ?

    • @giahuyhoang8722
      @giahuyhoang8722 3 роки тому +3

      Because n^2 larger than n then O(n^2) is enough

    • @kgkcStudios
      @kgkcStudios 3 роки тому +3

      You can just take the largest degree of a polynomial

    • @42war_pig31
      @42war_pig31 3 роки тому +4

      From the definition of Big O, there must exist some constant c, such that c*n^2 >= n^2+n. And since n^2 is quadratic and n is linear, n has almost no effect on n^2 when n is very large. If you scale constant c large enough, you'll find a c where it satisfies the relation I stated earlier.

  • @thomasvrh
    @thomasvrh 4 роки тому +1

    Nice!

  • @enricodalpos5039
    @enricodalpos5039 2 роки тому

    Why at 11:20 he is doing T(n-k) = 0 ? and not T(n)

    • @JoseWaldier
      @JoseWaldier 2 роки тому

      because that is the base case

  • @MrAgj200
    @MrAgj200 2 роки тому +1

    great video

  • @abnerandreymartinezzamudio3366

    Finally some material with American accent

  • @javawithhawa
    @javawithhawa 2 роки тому

    I love you

    • @randerson112358
      @randerson112358  2 роки тому +1

      Haha I appreciate that! Thanks for watching Java With Hawa.

  • @srisindhu7249
    @srisindhu7249 2 роки тому +2

    More easier method is Master theorem for decreasing function can be used instead.

  • @user-mz2kr4eh7r
    @user-mz2kr4eh7r Рік тому

    Literally save my ass lol

  • @IanGrahn
    @IanGrahn Рік тому +1

    This was so hard to follow

  • @yubdr
    @yubdr 2 місяці тому

    randerson112358 da goat

  • @Krontalll
    @Krontalll 3 роки тому +12

    T(n) =0 if n= to what???? AND T(n)= T(n-1)+2n if n= TO WHAT????. Please give a fully equation for better understanding. Thanks

    • @hatacoyama1246
      @hatacoyama1246 Рік тому +1

      it says T(0) is 0 and T(n) for all other cases

  • @jasonli1060
    @jasonli1060 3 роки тому

    noice

  • @tomtian9622
    @tomtian9622 2 роки тому +1

    damn, can not understand

  • @elleelleelleelle_______
    @elleelleelleelle_______ 2 роки тому

    Uninentional asmr 😏😏😏

  • @ruslandraganov9322
    @ruslandraganov9322 4 роки тому +2

    What the fuck is he talking about?

  • @kells9k
    @kells9k Рік тому

    Volume a bit too low mate