A beautiful result in Calculus: Solution using Laplace transforms ( Integral cos(x)/(x^2+1) )

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  • Опубликовано: 6 янв 2025

Комментарии • 239

  • @Fematika
    @Fematika 6 лет назад +436

    That was one of the funniest things I've seen all week.
    EDIT : Also, pi/e = 1, why didn't you write it like that?

    • @Bhuyakasha
      @Bhuyakasha 6 лет назад +23

      pi/e = 1.15572734979

    • @Fematika
      @Fematika 6 лет назад +99

      Bhuyakasha It’s an “engineering are bad at math” joke.

    • @henrebooysen2513
      @henrebooysen2513 4 года назад +31

      Fundamental theorem of engineering

    • @harelkariv1477
      @harelkariv1477 4 года назад +21

      By the fundamental theory of engineering, pi=3, e=2,and because we know that for large enough values of 2 2=3 we get pi=e which implies pi/e=1

  • @blackpenredpen
    @blackpenredpen 6 лет назад +214

    LOLLLLLL at 3:30 wtf. Hahhahah

    • @EmissaryOfSmeagol
      @EmissaryOfSmeagol 6 лет назад +12

      Gotta love the Roblox effects

    • @nicholasleclerc1583
      @nicholasleclerc1583 6 лет назад +3

      I couldn’t even understand it !!! X D

    • @arturogonzalez6184
      @arturogonzalez6184 6 лет назад +7

      the new mortal kombat game looks pretty sick :D

    • @Witiok1992
      @Witiok1992 6 лет назад +4

      It was hillarious!

    • @brendanlee1707
      @brendanlee1707 4 года назад

      Omg, my two favorite math senpais are converging in this parallelism of infinitely divergent software of youtube

  • @wontpower
    @wontpower 6 лет назад +132

    **Flawlessly uses Laplace transforms to solve integral** **forgets the s at the end of bois**

  • @46pi26
    @46pi26 6 лет назад +208

    Gauss, Riemann, Dirichlet, and Euler start a mathematics fight club where you beat people to death with integrals. The last man standing was papa flammy, and he wasn't even part of the club

    • @PapaFlammy69
      @PapaFlammy69  4 года назад +18

      Damn mah boi Hunter I miss you down there in the comment section! Are you doing well?

  • @Beniguitar94
    @Beniguitar94 6 лет назад +90

    14:18 Sure you can get that result from other integrals. For example, integral(pi/e · dx) defined from 0 to 1. I'm just being annoying ;P Great video! Really enjoyed it!

  • @Ayrton-Da-Silva
    @Ayrton-Da-Silva 6 лет назад +25

    LOL you are so funny, loved the new challenger approaching joke!

  • @Soundillusions94xyz
    @Soundillusions94xyz 6 лет назад +22

    I admire your mathematical ability SOOO much, keep doing what you're doing. :)

  • @benburdick9834
    @benburdick9834 6 лет назад +83

    I'm beginning to think that papa flammy is a big fan of laplace transformations...

    • @Davidamp
      @Davidamp 6 лет назад +14

      He's a physicist :v

    • @somedude1666
      @somedude1666 3 года назад +1

      That's because laplace transforms are fuc,king dope bruh.

  • @danielescotece7144
    @danielescotece7144 6 лет назад +47

    Flammable Maths - Abusing the linearity of everything makes me happy🤣

  • @labzioui1
    @labzioui1 6 лет назад +57

    “Pure mathematics is, in its way, the poetry of logical ideas.” ~Albert Einstein !!!

    • @buttapotato1233
      @buttapotato1233 4 года назад +1

      “And that’s why poetry is not used very often because it is completely unnecessary and complicated” - me

    • @maxwellsequation4887
      @maxwellsequation4887 4 года назад +1

      ALBERT GODSTEIN

  • @SeverSpanulescu
    @SeverSpanulescu 4 года назад +12

    For engineers: Wolfram Mathematica gives the right answer instantly. When you're in a hurry, of course. If you have some time, try it with the residue theorem.

  • @diegopablogordillovaras106
    @diegopablogordillovaras106 6 лет назад +3

    Wow. My mind flew across mathematical lightyears! I think my calculus was really getting a little rusty. Thank you! I just got smarter just by watching this video. Instant subscription!

  • @markovuksanovic14
    @markovuksanovic14 6 лет назад +37

    So according to my engineering calculations, the result of this integral is obviously 1.

  • @escobasingracia962
    @escobasingracia962 6 лет назад +10

    Best 15 minutes of my life. Please keep doing this kinds of videos.

  • @user-wu8yq1rb9t
    @user-wu8yq1rb9t 2 года назад

    *Papa Bruce Lee* (min: 3:15)
    Thank you so much dear Papa, great.
    I learned and enjoyed.

  • @soliscrown1272
    @soliscrown1272 6 лет назад +4

    Great video! Very elegant solution.

  • @lenoel7666
    @lenoel7666 6 лет назад +1

    Mach weiter so, immer eine Freude ein neues Video von dir zu sehen.:)

  • @ThAlEdison
    @ThAlEdison 6 лет назад +25

    I would've combined 𝜋/2(s/(s²-1)-1/(s²-1)) into 𝜋/2((s-1)/(s²-1))=𝜋/2(1/(s+1))

  • @iuribachnivsky3022
    @iuribachnivsky3022 5 лет назад +1

    Aww, I first read about this back in....2001? This is one of the coolest integrals ever.

  • @TrickingSeba
    @TrickingSeba 6 лет назад +1

    Durch Zufall auf deinen Kanal gestoßen und innerhalb von paar Tagen alle Videos geguckt.
    Bitte mach weiter so :^)

  • @Jose-vp3gb
    @Jose-vp3gb 5 лет назад +3

    Im finishing my semester and all its going crazy, but 3:30 really made me laugh af. Thanks man!!!!!!!!

  • @debajyotisg
    @debajyotisg 6 лет назад

    At @12.55 we could get a faster result by simplifying the expression in s to get ~ 1/(s+1), the IL of which is exp(-t) .
    This is such a great video. Good job.

  • @EmissaryOfSmeagol
    @EmissaryOfSmeagol 6 лет назад +1

    Hey man, nice vid! That is a really nice result.

  • @blazep5881
    @blazep5881 6 лет назад +9

    Flammy always wins

  • @alexander51413
    @alexander51413 6 лет назад +17

    At 11:56, can't you simplify the expression to pi/2 * (1/(s+1)) and avoid all of the hyperbolic stuff

    • @kummer45
      @kummer45 2 года назад

      I was about to contour integrate. Considering f(z)....:3

    • @Noam_.Menashe
      @Noam_.Menashe 2 года назад

      @@kummer45 The contour integral is very literally two steps.

  • @JustSimplySilly
    @JustSimplySilly 6 лет назад

    That was a good fight at 3:30. Keep it up.

  • @RockNostalgic
    @RockNostalgic 6 лет назад +2

    This Integral could also be solved by residue theorem very elegant. With this approach you can almost read off the result from the definition ;)

  • @gammaknife167
    @gammaknife167 6 лет назад +116

    pi/e? Isn't that just 1?

    • @TrickingSeba
      @TrickingSeba 6 лет назад +43

      And sin(x) = x , it's trivial

    • @TrickingSeba
      @TrickingSeba 6 лет назад +11

      Tobias Görgen Yes i study chemical engineering and you?

    • @V-for-Vendetta01
      @V-for-Vendetta01 6 лет назад +4

      I don't get it, why is it a joke that engineers are bad at math? XD

    • @angelmendez-rivera351
      @angelmendez-rivera351 6 лет назад +7

      Rishabh Vailaya Because is their derivations and calculations, they are never rigorous or formal, and they approximate a lot. Not that that is a bad thing: in fact, it’s necessary to do it in most cases. But sometimes it’s easy to take it too far, and mathematicians don’t exactly like that paradigm.

    • @seroujghazarian6343
      @seroujghazarian6343 5 лет назад

      NO!

  • @w.s8605
    @w.s8605 5 лет назад +25

    at the end of the video you wrote ( thank you

    • @tomkerruish2982
      @tomkerruish2982 4 года назад

      It's supposed to be a heart, turned sideways.

    • @ahuman6546
      @ahuman6546 4 года назад +2

      @@tomkerruish2982 r/wooosh

  • @3기오세현
    @3기오세현 6 лет назад

    Thank you for showing wonderful Calculus technique!

  • @GermanSnipe14
    @GermanSnipe14 6 лет назад +23

    God math was interesting but it's so much more interesting when memes are integrated within the teaching MMMMMMMMMMMMMMMM YUM

  • @omarbaratelli3831
    @omarbaratelli3831 6 лет назад +2

    Hi Flammable Maths... I think we can do more simpler... because the Laplace transform of I(t) is just (pi/2)* (s - 1)/(s² - 1) which is (pi/2)*(1/(s+1)). Therefore, using the linearity of the inverse Laplace transform, we obtain that I(t)=(pi/2)*L^(-1) {1/(s+1)}(t) = (pi/2)*exp(-t). Since I=2*I(t=1) we have: I=2*(pi/2)*exp(-1)=pi/e and we're done. Have a nice week-end :)

  • @Giganesh_exe
    @Giganesh_exe 5 лет назад +1

    So it equals 1! That's so beautiful

  • @Jack__888
    @Jack__888 6 лет назад +1

    My favourite youtube channel ever

    • @mihaiciorobitca5287
      @mihaiciorobitca5287 6 лет назад

      Flammable Maths i would be sooo happy if you could be my teacher

  • @kummer45
    @kummer45 2 года назад +2

    With all honesty I wish you become a doctoral degree in mathematics and achieve a great contribution in this field. You deserve this. You are a natural teacher. Your content worth. It helps people get interested in this discipline.
    Besides, I think math is more than just a discipline.....

  • @FernandoVinny
    @FernandoVinny 6 лет назад

    Absolutely beautiful, elegant and surprising!

  • @j2011j2015j
    @j2011j2015j 6 лет назад

    I love your videos it brings back happy memories from University

  • @pronaybiswas7524
    @pronaybiswas7524 6 лет назад

    love this channel

  • @nilenninju4709
    @nilenninju4709 5 лет назад +3

    Flammy: "Sooo now wee can plug every thing in"
    Me: 😃

  • @철-l3n
    @철-l3n 6 лет назад

    Amazing. I think this technique can be the key idea to previous videos.

  • @Manish-uk2ow
    @Manish-uk2ow 4 года назад

    You did it beautifully

  • @skeletonrowdie1768
    @skeletonrowdie1768 6 лет назад +2

    thanks for showing how to do the inverse laplace transform! It really is like integrating, because you know the integral by knowing it's derivative. In this case, you know the inverse laplace transform because you know the laplace transform of the result. Pff haha.

  • @nullplan01
    @nullplan01 6 лет назад +29

    You know, you could have simplified the (s - 1)/(s² - 1) before doing the inverse Laplace transform. Might have been simpler...

    • @gamma_dablam
      @gamma_dablam 5 лет назад

      Assuming s =/= 1

    • @Charles.Wright
      @Charles.Wright 5 лет назад +1

      @@gamma_dablam - that's implicit

    • @chazzaca
      @chazzaca 4 года назад +1

      I was thinking the same thing!! The above equations from FG implies s ^= +-1 and that he only needed to take the inverse LT of 1/(s+1) which reduces to 1/e^t. In addition, if you're going to use a Laplace Transform why not replace cos(x) as Re(e^(ix)) from Euler's formula?

    • @frenchimp
      @frenchimp 3 года назад

      @@gamma_dablam This has already been assumed!

  • @kennypatel3985
    @kennypatel3985 3 года назад

    Thanks a lot! the way you explained is awesome

  • @matematicasemplice
    @matematicasemplice 4 года назад

    Sehr schön! Gratulierungen!

  • @kqp1998gyy
    @kqp1998gyy 4 года назад +1

    Beautiful

  • @chessandmathguy
    @chessandmathguy 6 лет назад

    Beautiful. Absolutely beautiful.

  • @Mr_Mundee
    @Mr_Mundee Год назад

    ur not a mathematician, you're a mathematician AND a comedian

  • @rockybond42
    @rockybond42 6 лет назад +3

    3:00 bis 3:45 ist der beste Witz, dass ich in einem Mathevideo gesehen habe.

  • @willthescienceguy
    @willthescienceguy 5 лет назад +3

    12:40 "What are thooooooose" :)

  • @taeim9197
    @taeim9197 6 лет назад

    You can just use this: 1/(AB) = (1/(B-A))(1/A - 1/B) without solving (Ax+B)/(x^2+1) + (Cx+D)/(x^2+s^2) = 1/((x^2+s^2)(x^2+1))

  • @mustafamalik4211
    @mustafamalik4211 5 лет назад

    5:55, where did the s go from the top?

  • @juandiegoparales9379
    @juandiegoparales9379 4 года назад +2

    Dude, I'm really interested to domain this theme (the Laplace transform), could you tell, which should be the things I need to study to have good bases when I start to study this heavily?

  • @FrederikFalk21
    @FrederikFalk21 5 лет назад

    at 9:00 couldn't s just be equal to plus/minus one? Then s squared minus 1 is zero and A can assume any value.

  • @Mr_Mundee
    @Mr_Mundee Год назад

    for the pdf, you can just do a/(x^2 + 1) + b/(x^2 + s^2) bcz it's just product of linear equations in terms of x^2 so u made ur life a bit harder there

  • @damiandassen7763
    @damiandassen7763 6 лет назад

    0:20 whoooaaaah savage mathematian

  • @valentinandrada9340
    @valentinandrada9340 5 лет назад

    10:50 i have a question. can u realy say that sqrt(s^2)=s? s is a complex number by definition of Laplace Transforms. I dont remember, but maybe it's related to Re (s)

  • @dibendupal3865
    @dibendupal3865 6 лет назад +1

    Sir you can do the partial fraction work easily by taking x^2=some variable u and can apply the same partial fraction as no x term is present

  • @kedarbahulkar189
    @kedarbahulkar189 4 года назад +1

    Amazing . Thank you

  • @joaquin6719
    @joaquin6719 4 года назад

    Nais video, specially min 3:00

  • @thomassinha5301
    @thomassinha5301 5 лет назад +1

    Oh yeah? What about the integral from 0 to pi/e of 1?

  • @silasrodrigues1446
    @silasrodrigues1446 6 лет назад +2

    Where do you bring these solutions from? You're amazing!

  • @CDChester
    @CDChester 6 лет назад +6

    THE SPICY MEMES MUH BOIIIIIIS!!!!!!!!!!

    • @CDChester
      @CDChester 6 лет назад +1

      "That's hard to say .. Laplace Transformation." *Goes on saying it like 12 times quickly without batting an eye*

  • @thomasblackwell9507
    @thomasblackwell9507 2 года назад

    That’s right, they are coming for you, but with giant butterfly nets!

  • @temurson
    @temurson 6 лет назад

    You make great videos man, that really helps me learn new things. I am only the beginner, so could you please give me a clue my can't we change the order of integration so easily? Just tell what topic I need to read, no need to tell the whole story. Thx.
    BTW: best animation I've ever seen

  • @andresvasquez5411
    @andresvasquez5411 4 года назад

    does someone know the name of the french music when papa flammy deafeted papa Lebesgue, papa Fubini, and papa Wikipedia?

  • @hach1koko
    @hach1koko 4 года назад

    12:00 you could have simplified that further, s/(s^2-1)*pi/2*(1-1/s)=pi/2*s(s-1)/(s(s^2-1))=pi/(2(s+1))

  • @travorliu1192
    @travorliu1192 4 года назад

    It is also possible by looking up Fourier transform table

  • @areebuddinphundreimayum9839
    @areebuddinphundreimayum9839 10 месяцев назад

    Why don't you use lagrange interpolation to find the partial fraction decomposition quickly?

  • @danielkirilov8065
    @danielkirilov8065 6 лет назад +1

    I just imagine myself at the corner of the room, watching you kicking the air :^D

  • @danielmilyutin9914
    @danielmilyutin9914 6 лет назад

    Cool. I've noticed one thing to simplify.
    s/(s²-1) -1/(s²-1)=1/(s+1) =~> exp(-t)

  • @jameswilson8270
    @jameswilson8270 6 лет назад

    Awesome solution!

  • @gnikola2013
    @gnikola2013 6 лет назад +6

    4:20 Nice and fine? You mean cool and good

  • @arsenmingo62
    @arsenmingo62 3 года назад

    The general solution is pi/e^a (for cos(ax))

  • @WhisDragonBallSuper
    @WhisDragonBallSuper 5 лет назад +1

    Do it again with residu theorem but in only 3 minutes

  • @Mike-dr1hz
    @Mike-dr1hz 6 лет назад

    I appreciate the memes, my man. I'd be pleased if you salted my dish, bartender

  • @Ideennot
    @Ideennot 6 лет назад +1

    Thanks for this!

  • @lewisbulled6764
    @lewisbulled6764 6 лет назад

    What is the difference between a definite integral from -inf to inf and an indefinite integral? Is it just that it will give you a value rather than a function?

  • @Jack__888
    @Jack__888 6 лет назад +1

    Such an amazing boi, isn't he? ☻

  • @KalikiDoom
    @KalikiDoom 6 лет назад

    truly amazing!

  • @Spinodal23
    @Spinodal23 4 года назад

    Is there any solutions using series expansion?

  • @almightyhydra
    @almightyhydra 6 лет назад

    There were a lot of "it's not equal to zero so can be cancelled" handwavyness, can you justify it?

  • @MrTereres
    @MrTereres 6 лет назад +2

    What about the integral of sinx/(x^2+1) from 0 to infinity? Can it be expressed in terms of π, e or other known constants? I did a little search on the net and I found only numerical approximations to it, not an exact value. Also, trying the same approach as this video, it leads to ln(s)/(s^2-1) and I have no idea what is the inverse Laplace transformation of this one. Any idea if we can proceed from here or do we need a different approach for this one?

    • @MrTereres
      @MrTereres 6 лет назад +1

      Thanks for the immediate response! Appreciated! I really wish you try it if you find the time. :)

    • @omarbaratelli3831
      @omarbaratelli3831 6 лет назад

      Hi :) if you want the exact value of the integral of sin(x)/(x^2+1) from 0 to +infinity you should use the Exponential integral function Ei and then the exact value is just (Ei(1)-e^2*Ei(-1))/2e where Ei is not an elementary function but a special one... and so no results can be obtained in terms of real numbers like pi, e or other known constants. I hope this helps you. Bye :)

  • @RetsamX
    @RetsamX 6 лет назад +1

    The new smash bros looks amazing!
    I love these types of videos

  •  6 лет назад

    Math-ninja-papaflammy is just awesome. Thou avoid some ChuckNorris-substitution if I can say ...

  • @ericl8743
    @ericl8743 5 лет назад

    You make me miss mathematics courses!

  • @desertrainfrog1691
    @desertrainfrog1691 2 года назад

    How do you deal with chalk dust?
    ʕ ・ ᴥ ・ ʔ

  • @sajidrizvi4665
    @sajidrizvi4665 6 лет назад +1

    That fight tho! :)

  • @cameronbetts3902
    @cameronbetts3902 5 лет назад

    So I finally learn trigonometric integrals next week, so then I'm try to understand this again later

  • @dr.merlot1532
    @dr.merlot1532 6 лет назад +1

    Hahaha, you showed that dominated convergence theorem who is boss!

  • @danielkirilov8065
    @danielkirilov8065 6 лет назад

    :^> You were on a pretty hard drugs after the 3rd minute, I admire you, Math God.

  • @xhourglazzezx
    @xhourglazzezx 6 лет назад

    This is amazing. 😍

  • @TheNachoesuncapo
    @TheNachoesuncapo 4 года назад +1

    Do You still answer qurstions from old videos?

  • @Origamiztec
    @Origamiztec 6 лет назад +1

    Bro, I love to work with these videos when I understand them, and just watch in awe when I don't. What level of math or physics are laplace transforms taught? Max I've learned so far is Multivariable Differential Calculus and Physics C

    • @orangeguy5463
      @orangeguy5463 6 лет назад +2

      At my university Laplace transforms are introduced in Differential Equations because of their phenomenal way to transform high order constant coefficient differential equations into algebraic problems (as long as initial conditions are known). Laplace and Fourier transforms are explored more in depth in higher level (graduate or senior level undergraduate) complex analysis classes.

  • @chriswinchell1570
    @chriswinchell1570 4 года назад

    Nice. I do think think you risk a hernia from all that heavy lifting. I thought you were just gonna make cos(x) into e^(jwx), recognize this as Fourier transform of Cauchy, set w=1, taste victory, and get drunk.

  • @vvladgfhjkm
    @vvladgfhjkm 6 лет назад

    Boy, you rock!

  • @nuklearboysymbiote
    @nuklearboysymbiote 5 лет назад

    isn't π/e just equal to 1 (by the fundamental theorem of engineering)

  • @lionelinx7
    @lionelinx7 6 лет назад +1

    cool bro

  • @gabrieledoria2896
    @gabrieledoria2896 6 лет назад

    Bro you are a magician ;)

  • @AndDiracisHisProphet
    @AndDiracisHisProphet 6 лет назад +17

    But is it rational?^^

    • @AndDiracisHisProphet
      @AndDiracisHisProphet 6 лет назад +5

      Me neither :D

    • @AndDiracisHisProphet
      @AndDiracisHisProphet 6 лет назад +4

      Were is Peyam when you need him? Doing something about the Chebyshev boi....

    • @angelmendez-rivera351
      @angelmendez-rivera351 6 лет назад +8

      π is approximately 3
      e is approximately 3
      Therefore, π/e is approximately 1.
      1 is rational
      Therefore, π/e is rational.
      Q.E.D.
      ;)

    • @constantin159753
      @constantin159753 6 лет назад +8

      @@angelmendez-rivera351 Papa Euler would like to know your location