MESMERIZING integral result! int 0 to infty e^(cos(x))cos(sin(x))/(1+x^2)

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  • Опубликовано: 24 окт 2024

Комментарии • 36

  • @mcalkis5771
    @mcalkis5771 2 месяца назад +21

    Proud to say I was able to solve this on my own before watching the video. You've taught us well Mr 505

  • @CM63_France
    @CM63_France 2 месяца назад +34

    Hi,
    "ok, cool" : 1:33 , 2:49 , 3:53 , 6:27 ,
    "terribly sorry about that" : 1:47 , 2:55 , 4:05 .

    • @cougar1861
      @cougar1861 2 месяца назад +7

      Are there any records for number of each 1) "OK, cool" and 2) "terribly sorry about that" ... per minute of video?

    • @CM63_France
      @CM63_France 2 месяца назад +2

      @@cougar1861 I thought about something like that, or maybe the distribution of them in the time, but we have to few data for that.
      We could rather do some qualitative studies, like, for instance, the time of the first occurrence or the second one.
      For instance I think that the first occurrence of the "ok, cool" comes (now) within the first 5 seconds, may be less, whereas for the second one, it's a bit more random.
      Also, we can say that they occurs after an important information, such as an important result or an abstract of some strategy.
      A very interesting topic, isn't it?

    • @maths_505
      @maths_505  2 месяца назад +3

      @CM63_France indeed it is

  • @Sugarman96
    @Sugarman96 2 месяца назад +5

    The way that immediately came to my mind is to notice that the integrand is an even function, so you can expand the integration from negative to positive infinity. Following that, at 4:23 you're left with what is just the inverse Fourier transform of e^-|t| (barring some constants of course) evaluated at k.
    You should totally introduce the Fourier transform to the toolbox in your videos, electrical engineers love it for a reason.

  • @michaelihill3745
    @michaelihill3745 2 месяца назад +1

    Great solution. I laughed to myself when the significance of the final infinite series dawned on me.

  • @Player_is_I
    @Player_is_I 2 месяца назад

    Truly mesmerizing! Stunning result as well

  • @math-69
    @math-69 2 месяца назад +6

    at 6:09 you made a mistake on the integral from 0 to infty of cos(kx)/(1+x^2) the correct answer is pi/(2 e^k)

    • @XHunter-lm6qp
      @XHunter-lm6qp Месяц назад +3

      Exactly ,your right it's an error

  • @owenvaughn3191
    @owenvaughn3191 2 месяца назад

    You always pick the coolest integrals 😊

  • @xleph2525
    @xleph2525 2 месяца назад +5

    Very integral!
    Much mesmerizing!
    And 8 minutes ago??

  • @aleksandervadla9881
    @aleksandervadla9881 2 месяца назад +5

    You could use residue theorem right away so you dont have to do series expansion

    • @maths_505
      @maths_505  2 месяца назад +5

      Been there
      Done that
      Link in description

  • @MrWael1970
    @MrWael1970 2 месяца назад

    Very cool. Thank you.

  • @ikarienator
    @ikarienator 2 месяца назад +2

    I think this is off by a factor of 2. pi e^(e^-1) / 2. 6:00 result of that integral is pi/2/e^k.

  • @slavinojunepri7648
    @slavinojunepri7648 2 месяца назад +1

    Fantastic

  • @roshanmadhav8876
    @roshanmadhav8876 2 месяца назад +12

    Shouldn’t it all be over 2 ?

    • @riadsouissi
      @riadsouissi 2 месяца назад +3

      Indeed

    • @maths_505
      @maths_505  2 месяца назад +6

      Indeed x 2 which should cancel out the factor of 1/2 thereby justifying my result (terribly sorry about that)

    • @rebel2358
      @rebel2358 2 месяца назад +3

      Where’s the extra x2 coming from. As far as I can tell the final answer should be pi/2 e^1/e no?

  • @RSLT
    @RSLT 2 месяца назад

    Wow, that's very cool 😎

  • @robertsandy3794
    @robertsandy3794 2 месяца назад

    Hi Kamal,
    You make use of the Dominating Convergence Theorem quite a bit. Have you considered doing a video proving this theorem?
    Just a thought

    • @asparkdeity8717
      @asparkdeity8717 2 месяца назад

      please don’t ruin the fun with analysis 🙏

  • @sachacloot1925
    @sachacloot1925 2 месяца назад

    hey i just want to know if u use a trick i don't understand or smth but on wolframe your integrale from 0 to inf of cos(kx)/1+x^2 = pi/2e^k , i have personnaly solve it using contour integration and found the same resulte so ig it's the good resulte but something seem wrong.. may wolfram just wrong ?

  • @ryan_journey
    @ryan_journey 2 месяца назад +1

    Could u pleaseee explain to me why can we make the "Re()"real part outside of the integral and why can we use it again whenver we want to like shown at 4:40

    • @maths_505
      @maths_505  2 месяца назад +2

      I wish latex was integrated here to make the explanations alot easier but unfortunately I don't think RUclips plans to make the platform more math friendly. So I'm just linking a math stackexchange post here:
      math.stackexchange.com/questions/3817007/why-can-we-take-out-the-real-part-operator-from-under-the-integral

    • @ryan_journey
      @ryan_journey 2 месяца назад +1

      @@maths_505 Thank You soooo much for your time dudde , Hope u solve hatder integrals and get much more gym gainzz

    • @maths_505
      @maths_505  2 месяца назад +1

      @@ryan_journey thanks mate

  • @XHunter-lm6qp
    @XHunter-lm6qp Месяц назад

    We can solve this using the fact that (e^cosx)cos(sinx)= sum to infinity of cosnx/n!

  • @orionspur
    @orionspur 2 месяца назад +3

    Ho-leee cow

    • @vladimir10
      @vladimir10 2 месяца назад +1

      Yeah
      That's what I felt as well!
      Breathtaking

  • @ATYPICALJEEASPIRANT
    @ATYPICALJEEASPIRANT 2 месяца назад +1

    hey are you indian ?

  • @redroach401
    @redroach401 2 месяца назад +1

    Legends know this is a re-upload

    • @maths_505
      @maths_505  2 месяца назад +1

      It's not a re-upload.....I previously solved it using contour integration.

    • @redroach401
      @redroach401 2 месяца назад +1

      @@maths_505 Oh my bad