Awesome integral solved using contour integration

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  • Опубліковано 20 січ 2025

КОМЕНТАРІ • 31

  • @averagegamer9513
    @averagegamer9513 Рік тому +4

    From I have seen in complex analysis, ln is often used to denote the multivalued logarithm function, whereas Log represents the principal branch of the natural logarithm.

  • @Unidentifying
    @Unidentifying Рік тому

    your skills are insane mate. great videos, nice and challenging

  • @jieyuenlee1758
    @jieyuenlee1758 9 місяців тому

    22:27
    Int (cosx)/(x²+4) at interval (-inf,inf)=pi/2e²

  • @danielrosado3213
    @danielrosado3213 Рік тому +2

    Love it! Keep making amazing videos!

  • @violintegral
    @violintegral Рік тому +2

    Using some substitutions, you can show that evaluating this integral is equivalent to showing that the integral from 0 to infinity of (cos(2x)*log(x) + pi/2*sin(x))/(x^2 + 1)*dx = 0, which I think might be an even more interesting result. This makes me think there might be a solution to this integral using symmetry, but I have no idea how to go about showing that.

    • @renerpho
      @renerpho Рік тому

      WolframAlpha does not like that definite integral.

  • @thomasblackwell9507
    @thomasblackwell9507 Рік тому +1

    Would you please do this integral using the Feynman Technique please.

  • @xyzxyzxyzxyz636
    @xyzxyzxyzxyz636 Рік тому +2

    This is it! Thanks!

  • @MochiClips
    @MochiClips Рік тому +1

    Called it!

  • @manstuckinabox3679
    @manstuckinabox3679 Рік тому +1

    Oh hey you can evaluate this integral using comple- oh ok..
    man that;s such a beutiful integral, you're supply is always up to the damand, best math dealer out here.
    5:00 I think it goes like this
    ln : Real Logarithm
    log : any branch of the logarithm
    Log: principle branch of the logarithm

    • @maths_505
      @maths_505  Рік тому

      We always need the principle branch so log all the way🥳

  • @thomasblackwell9507
    @thomasblackwell9507 Рік тому +7

    Sympathy for your cat! Give it a bowl of fresh milk!

  • @RanBlakePiano
    @RanBlakePiano Рік тому

    Fascinating !

  • @zygoloid
    @zygoloid Рік тому +2

    Very cool to see sin x appear by combining the two halves of the integral.
    Do we need to consider the little gamma integral at all? There's no discontinuty at z=0.

    • @renerpho
      @renerpho Рік тому

      What's log(z) at z=0?

    • @zygoloid
      @zygoloid Рік тому

      Thanks, I'm not sure how I missed that; the video even explicitly points it out.

  • @zunaidparker
    @zunaidparker Рік тому +3

    This is second-year university level calculus, so I fully expect log = natural logarithm. Ln is for high school or introductory calculus and should be matured out of as quickly as possible.

    • @maths_505
      @maths_505  Рік тому

      Indeed....
      But ofcourse I wasn't referring to you my fellow knight of dark math😂
      I was referring to those who are just entering the dark realm of higher math....
      However I do find it strange that many great books in higher math still use ln....I think that could either stem from rebellion towards complex analysis or maybe they just don't want to get rid of the old notation.

    • @renerpho
      @renerpho Рік тому

      Can't hurt to be cautious 🙂

  • @studyhelp7479
    @studyhelp7479 Рік тому

    Absolutely LOVE your content. And, i have to say, with something this fiddly", when you go "What the Fuck" ... it just makes me smile. I say this all the time when solving problems!! COOL, man! Is there anywhere where you do / could tell us a bit about yourself / your background? I really rate you, and think your stuff is GREAT. Really enjoy it, actually. CHEERS! Patrick.

    • @maths_505
      @maths_505  Рік тому

      I'll do a video on that someday

  • @abutorabrahman4114
    @abutorabrahman4114 Рік тому

    It’s really cool..Waiting to see more like this❤️❤️

  • @dihinamarasinghe9278
    @dihinamarasinghe9278 Рік тому

    Pure Awesomeness dude...... #complexanalysis

  • @hacker2ish
    @hacker2ish Рік тому +1

    Do integral from 0 to pi/4 of arctan(sqrt((1-tan(x))/2))

  • @anasharere
    @anasharere Рік тому +1

    Is there another way to solve the integral? For example, Laplace or Fayman

    • @maths_505
      @maths_505  Рік тому +1

      You can split it into 2 integrals and perhaps find out new ways to evaluate it

  • @endersteph
    @endersteph Рік тому

    Hi, can someone please explain why 1/|R²e²ᶲⁱ + 4| ≤ 1/(R² - 4)?
    Edit: Ok I think I figured it out actually. I'm just confused why he said it like it is trivial.

  • @Black47Heart
    @Black47Heart 10 місяців тому

    Now we talking ....

  • @wowbagger7168
    @wowbagger7168 Рік тому +1

    Greetings to your cat.

  • @hamzamsila4614
    @hamzamsila4614 Рік тому

    I can solve it by one trick
    lnx=int [2yx^2/(1+x^2y^2)
    -2y/(1+y^2)] dy from 0 to infinity