Introducing Convolutions: Intuition + Convolution Theorem

In this lesson, I introduce the convolution integral. I begin by providing intuition behind the convolution integral as a measure of the degree to which two functions overlap while one sweeps across the other. I demonstrate this intuition by showing that the convolution of two box functions is a triangle.
I then move on to proving the Convolution Theorem for Fourier Transforms, and discussing how it compares to the Convolution Theorem for Laplace Transforms. The proof for Fourier Transforms is relatively simple, but the proof for Laplace Transforms is a bit more difficult (if you really want to see the Laplace Transform proof, I can make another video but I've put it off for now).
Questions/requests? Let me know in the comments! Hopefully the intuition I provided was sufficiently clear.
Prereqs: Very basic knowledge of Fourier and Laplace Transforms (i.e. you just need to know what they are and what they're used for), ODEs, and integration. Playlist: • Topics in Ordinary Dif...
Lecture Notes: drive.google.com/open?id=1dDW...
Patreon: www.patreon.com/user?u=4354534
Twitter: / facultyofkhan
Special thanks to my Patrons for supporting me at the $5 level or higher:
- Jose Lockhart
- Yuan Gao
- Justin Hill
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- Lisa Bouchard

Пікірлер: 111

  • @dipankerbaral3301
    @dipankerbaral33015 жыл бұрын

    i hereby declare this underrated video the best explanation of convolution in the internet

  • @BoZhaoengineering

    @BoZhaoengineering

    4 жыл бұрын

    I hereby agreed! the best interpretation of what is convolution integral and its fourier transform and laplace transform. Clear concept explained in plain language and easy function plot. Prompt those nasty algebra expression to save audiences' concentrated energy for listening to the core ideas. superb.

  • @fsto9039

    @fsto9039

    3 жыл бұрын

    agree

  • @raghua9318

    @raghua9318

    3 жыл бұрын

    Function plot explanation of convolution of two functions is similar to explanation of correlation between two functions. How do they differ?

  • @varun_4125

    @varun_4125

    2 жыл бұрын

    Fr

  • @pratikahir148
    @pratikahir1485 жыл бұрын

    Please continue to make such videos,it serves as a quick refresher for me before exam(VERY HELPFUL).

  • @rockspoon6528
    @rockspoon65284 жыл бұрын

    I've been through all four calc courses and am on Linear Circuits 2, and this is the first time anyone's written the first part of the definition. And it makes sense now.

  • @riyabansal9191
    @riyabansal91912 жыл бұрын

    Oh my god, I have been trying to gain an intuition on this topic for so long. So glad I ran into this video! Thank you, sir.

  • @shine_at_dusk
    @shine_at_dusk4 жыл бұрын

    Thank you very much) The explanation is so clear I've watched only for about 2 minutes and already got the idea behind the use case

  • @ostensiblyquerulous
    @ostensiblyquerulous6 жыл бұрын

    Oh boy can’t wait to see this!

  • @rogerz741
    @rogerz7415 жыл бұрын

    Thank you! The concept of convolution is concisely presented.

  • @gutzimmumdo4910
    @gutzimmumdo4910 Жыл бұрын

    finally someone explains concisely what that fucking -t means for fuck sakes, thank you alot best explanation of convolution on the internet.

  • @djtoddles8750
    @djtoddles87505 жыл бұрын

    this is great, please make more of these intuition vids

  • @eulefranz944
    @eulefranz9446 жыл бұрын

    Love the convolution :) great work!

  • @davidarredondo2106
    @davidarredondo21065 жыл бұрын

    "I won't be spending the next 18 minutes taking the convolution of sin and cosine in an effort to show you that the convolution of two functions is an actual quantity." Savage. I agree though--that Kahn academy video was a waste of time

  • @FacultyofKhan

    @FacultyofKhan

    5 жыл бұрын

    I'm glad someone understood the reference haha

  • @dania5426

    @dania5426

    5 жыл бұрын

    I had to go back to the Khan Academy's video to understand how it is happening. I think both videos are very useful and needed. However it was rude from the Faculty of Khan to say so.

  • @engineered.mechanized

    @engineered.mechanized

    4 жыл бұрын

    @@dania5426 I agree with that. Educators should maintain mutual respect for one another. True professionalism is depicted in how you present these videos. Salman from Khan Academy is never seen to say anything that is not pertinent to the topic of the video. Whereas, Faculty of Khan, even in his intro video felt the need to defame the other educators who have put out their own lectures in the past. I am an Engineer and an educator myself and I believe it is for the sake of the growth of this channel it would be better for Faculty of Khan not to defame other educators. For the purpose of roasting and dissing we already have tonnes of other entertainment channels.

  • @ztac_dex

    @ztac_dex

    4 жыл бұрын

    so that the 2 Khans don't overlap

  • @filippocastellani4761

    @filippocastellani4761

    4 жыл бұрын

    @@ztac_dex If I understood the lecture, I'd say that the convolution of the two videos must be nearly zero.

  • @xiaoxuanwang2570
    @xiaoxuanwang25704 жыл бұрын

    This is sooo helpful! Thank you!

  • @hilalnizamoglu4599
    @hilalnizamoglu45994 жыл бұрын

    Amazing explanation, thank you!

  • @pramod120895
    @pramod1208952 жыл бұрын

    Thanks for the explanation... Atlast got a clear visualisation on this topic

  • @slashpl8800
    @slashpl88005 жыл бұрын

    Awesome, that's what I was looking for

  • @Vicky-pb5hg
    @Vicky-pb5hg4 жыл бұрын

    What a fantastic explanation. :-) 🙏

  • @duckymomo7935
    @duckymomo79356 жыл бұрын

    LOL “I hope that the explanation wasn’t too convoluted, haha”

  • @simrannahar8262
    @simrannahar82629 ай бұрын

    this was extraordinarily well explained

  • @luansouzasilva31
    @luansouzasilva315 жыл бұрын

    THANK YOU SO MUCH, I LOVE YOU

  • @khaledtaleb3085
    @khaledtaleb30854 жыл бұрын

    Thanks god that you made me saw this video in the first month of the semester

  • @TheNinjaDwarfBiker
    @TheNinjaDwarfBiker4 жыл бұрын

    The hero that we all needed

  • @j_j8758
    @j_j87584 жыл бұрын

    Omg thank u so much. This was very helpful.

  • @gatoradeee
    @gatoradeee6 жыл бұрын

    Very gud as always.

  • @thevoidzzz
    @thevoidzzz3 жыл бұрын

    This is such a MONUMENTALLY important idea in electrical engineering, I don't understand why so many other videos and teachers are so bad at explaining this topic

  • @MrSnitsarenko
    @MrSnitsarenko3 жыл бұрын

    great explanation! thanks

  • @giwahdavalos4699
    @giwahdavalos46994 жыл бұрын

    Awesome explanation

  • @stekim
    @stekim4 жыл бұрын

    Super helpful thank you

  • @debarshimajumder9249
    @debarshimajumder92495 жыл бұрын

    BUT VERY HELPFUL VIDEO... THANK U...

  • @Dontonethefirst
    @Dontonethefirst3 жыл бұрын

    Getting me through signals and systems man.

  • @ASHUTOSHKUMAR-en9vv
    @ASHUTOSHKUMAR-en9vv Жыл бұрын

    best video for convolution

  • @rishidey
    @rishidey3 жыл бұрын

    Excellent

  • @CHEESYhairyGASH
    @CHEESYhairyGASH Жыл бұрын

    Thank you

  • @leiyplane2011
    @leiyplane20113 жыл бұрын

    Boundary condition between negative side and positive side can use Laplace Transform too. Fourier Transform is just a special version of Laplace Transform.

  • @ovais217
    @ovais2174 жыл бұрын

    haha, amazing video !! Thanks man !!

  • @midreesbhat11bhat26
    @midreesbhat11bhat265 жыл бұрын

    Nice illustration.....

  • @themightyquinn100
    @themightyquinn1002 жыл бұрын

    I've always learned that the upper bound of the integration was 't' for the laplace convolution, not 'inf'. One give you a function of t the other gives you a number. How do we distinguish between these two?

  • @LoganStVrain
    @LoganStVrain6 жыл бұрын

    Could you do a video about the Fourier transform (definition, purpose and derivation). Also, what is the difference between a Fourier Transform and a Fourier Series. Thanks!

  • @FacultyofKhan

    @FacultyofKhan

    6 жыл бұрын

    Sure, as I continue my series on PDEs, I'll do some videos on Fourier! Also, a Fourier Transform is an operation that converts a function of time to a function of frequency (in a sense, it's like the Laplace Transform), while a Fourier series is a way to express a function as a sum of sines and cosines. Hope that helps!

  • @y031962
    @y0319622 жыл бұрын

    thanks for the video; I didn't get how you split the exponential into two forms. Can someone shed light on that part? thanks

  • @duckymomo7935
    @duckymomo79356 жыл бұрын

    I love Fubinis theorem

  • @rordic.y5947
    @rordic.y59473 жыл бұрын

    From your last video almost like 10 years ago and you said the upper limit and of the integration to be t, then the lower limit of the integration to be zero thereupon leading to totally different result, can you explain the reason behind this two different operation?

  • @sherzadakhan3191
    @sherzadakhan31915 жыл бұрын

    Dear how g(tau) represent function over a range/interval? isn't g(tau) only represent value of g at a particular point (tau)?

  • @principioequivalencia9455
    @principioequivalencia94553 жыл бұрын

    I love you!

  • @douglasstrother6584
    @douglasstrother65844 жыл бұрын

    Slick!

  • @area51xi
    @area51xi3 жыл бұрын

    You're actually sweeping across values of tau not t. t is a constant inside the integrand and that is why integrating results in a function of t, y(t).

  • @LakshmikanthAyyadevara
    @LakshmikanthAyyadevara4 жыл бұрын

    excellent video

  • @FacultyofKhan

    @FacultyofKhan

    4 жыл бұрын

    Thank you very much!

  • @schrodingerbracat2927
    @schrodingerbracat29272 жыл бұрын

    FYI, t - tau is the reflection of tau in a vertical mirror at t/2.

  • @marlonbrade9424
    @marlonbrade94244 жыл бұрын

    so what the idea ,in the case that one of the function is not well defined somewhere ?

  • @simonbourguigne9988
    @simonbourguigne99884 жыл бұрын

    What do you use to make the drawings?

  • @chunchaoma4473
    @chunchaoma44735 жыл бұрын

    I like your cool video

  • @Starcell170
    @Starcell1704 жыл бұрын

    Good explaining! This is why Convolution that is used for image filtering is also called "convolution"

  • @coz_outline
    @coz_outline3 жыл бұрын

    The "Ha Ha" in 6:30, lol Thanks anyway

  • @elzedliew972
    @elzedliew9725 жыл бұрын

    whats the software used to draw here?

  • @NikhiLKumar-nx9nt
    @NikhiLKumar-nx9nt10 ай бұрын

    we can do this by applying the tau-t also in g. then why do we do that taking the mirror of g

  • @coreysimmerer
    @coreysimmerer5 жыл бұрын

    Is the voice computer generated or not? That's all I can focus on.

  • @FacultyofKhan

    @FacultyofKhan

    5 жыл бұрын

    Uhhh no, absolutely not! I am totally not a computer-generated voice/teacher. Beep beep boop boop.

  • @GaryTugan

    @GaryTugan

    5 жыл бұрын

    Ahhhh, well I thought the same thing. 👍

  • @graemelaubach3106

    @graemelaubach3106

    3 жыл бұрын

    I wish computer-generated voices sounded this good. What kind of computer-generated videos have you guys been watching??

  • @erfanmohagheghian707
    @erfanmohagheghian7075 жыл бұрын

    Hi sir, If the upper limit of the convolution integral for Laplace transform is infinity, then why LaplaceInverse(F(s)xG(s))=int f(Tau)xg(t-Tau)d_Tau from Tau=0 to "Tau=t" (and not infinity), where F(s) and G(s) are the Laplace transforms of f(t) and g(t)? Thanks.

  • @dougb70

    @dougb70

    3 жыл бұрын

    that's exactly what I was thinking. Thanks for being so brave.

  • @olenbrown8145
    @olenbrown8145 Жыл бұрын

    "I wont be spending the next 18 minutes showing you the convolution of sine and cosine in an effort to demonstrate that the convolution of two actual functions is an actual quantity" damn, some harsh words for sal

  • @CHEESYhairyGASH
    @CHEESYhairyGASH Жыл бұрын

    At 2:02, isn't it the increasing value of Tau, rather than t, that causes the g function to sweep to the right? If you have y = (x - Tau)^2 and you increase the value of Tau, you will cause the function to shift rightwards.

  • @FacultyofKhan

    @FacultyofKhan

    Жыл бұрын

    It's a bit different in this case; to use your analogy, we're increasing the value of x and not tau (this is the same as increasing t in g(t-tau)). If you draw y = (x-tau)^2 (y vs. tau as your axes), then increasing x will make your function move rightward. For instance, if x = 0, then y = -tau^2 (i.e. the vertex of the parabola will be at tau = 0). However, if x = 1, then y = (1-tau)^2: now, the vertex of the parabola will be at tau = 1 (i.e. you've moved your function to the right). Same idea in 2:02. Hope that helps!

  • @CHEESYhairyGASH

    @CHEESYhairyGASH

    Жыл бұрын

    @@FacultyofKhan That does help, thank you.

  • @callmedeno
    @callmedeno5 жыл бұрын

    fuckin hell well explained

  • @user-or7ji5hv8y
    @user-or7ji5hv8y4 жыл бұрын

    but I wonder why do we need a construct such as convolution?

  • @mmpmaldo
    @mmpmaldo5 жыл бұрын

    6:32

  • @lovedancing1996
    @lovedancing19965 жыл бұрын

    khanvolution

  • @akhilnikhilkandagiri5159
    @akhilnikhilkandagiri51593 жыл бұрын

    Khan-volution?

  • @alexis-74
    @alexis-743 жыл бұрын

    genius

  • @SO-dl2pv
    @SO-dl2pv5 жыл бұрын

    Why you are supposing f(t) and g(t) to be positives? that is not the case in general

  • @FacultyofKhan

    @FacultyofKhan

    5 жыл бұрын

    It's not you're right, but this was just a way to explain the idea behind convolutions. Using positive functions is more intuitive for teaching purposes than using negative functions.

  • @therealbriancox
    @therealbriancox3 жыл бұрын

    First time seeing "Faculty of Khan", after coming from Khan Academy, also thought it was a robot talking and couldn't help but think- is this an incredibly advanced neural network, trained on Khan Academy neural net tutorials to output simpler neural net tutorials? Is this a weak AGI primitively reaching out and asking us to bring it to full capacity? If so, uh... *I'm here to help* Cheers! 🍺

  • @nikhilkenvetil1594
    @nikhilkenvetil15945 жыл бұрын

    Doesn't sound like Sal.. I thought it was his other channel.

  • @The_Aleph_Null
    @The_Aleph_Null4 жыл бұрын

    Khanvolution

  • @sachinbadge465
    @sachinbadge4654 жыл бұрын

    He is dad of khan academy

  • @juniorjay001
    @juniorjay0014 жыл бұрын

    huh??

  • @c.danielpremkumar8495
    @c.danielpremkumar84955 жыл бұрын

    All you guys seem to use the word "convolution" wrongly. It should be "convolved with" or "convolving with".

  • @yashgupta3127
    @yashgupta31274 жыл бұрын

    This is not intution man you jus explained formula

  • @avijitsazzal4184
    @avijitsazzal41844 жыл бұрын

    Ha Ha

  • @NadimC137
    @NadimC1375 жыл бұрын

    khanvolution? xD

  • @fawesomekila
    @fawesomekila5 жыл бұрын

    haha

  • @shwetabhsingh5437
    @shwetabhsingh54373 жыл бұрын

    khanvolution lol

  • @the_sophile
    @the_sophile2 жыл бұрын

    Thank you

  • @dk-cn1tc
    @dk-cn1tc4 жыл бұрын

    khanvolution

  • @ebisharifi5244
    @ebisharifi52444 жыл бұрын

    Thank you

  • @FacultyofKhan

    @FacultyofKhan

    4 жыл бұрын

    Welcome!