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What is Euler's formula actually saying? | Ep. 4 Lockdown live math

3Blue1Brown

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Beginner. No background in the topic needed.

1.7M views6 years ago1 recommendation

Computer scienceMath for programmers

An intuitive explanation of Euler's formula, complex exponentials, and how they relate to rotation.

What does it mean to compute e^{pi i}? Full playlist: youtube.com/playlist?list=PLZHQObOWTQDP5CVelJJ1bNDouqrAhVPev Home page: 3blue1brown.com Brought to you by you: 3b1b.co/ldm-thanks Beautiful pictorial summary by @ThuyNganVu: twitter.com/ThuyNganVu/status/1258220129327800320 twitter.com/ThuyNganVu/status/1258220541686628353 Not on the "homework" to show that exp(x + y) = exp(x) * exp(y). This gets a little more intricate if you start asking seriously about whether the series really converge, what they converge to, and how exactly you define a product with infinitely many terms. For anyone curious about the technical details, what you would want to show is that the Cauchy Product of the series for exp(x) and exp(y) converges to the product of the values exp(x) and exp(y) for any particular x and y. That requires the Merten's Theorem. Thanks to these viewers for their contributions to translations Hebrew: Omer Tuchfeld ------------------ Video Timeline (Thanks to user "Just TIEriffic") Welcome Ending Animation Preview Reminders from previous lecture Q1: Prompt (Relationship with e^iθ=…) Q1: Results WTF, Whats The Function Exploring exp(x) Exploring exp(x) in Python Important exp(x) property Q2: Prompt (Given f(a+b) = f(a)f(b)…) Ask: Which is more interesting, special cases or the general case Q2: Results Will a zero break Q2? The e^x convention Q3: Prompt (i^2 = -1, i^n = -1) Ask: Zero does not break Q2 Q3: Results Comparison to Rotation Visualizing this relationship The special case of π Periodic nature of this relationship Q4: Prompt (e^3i) Q4: Results Explaining the celebrity equation Homework / Things to think about Ask: Zero does break Q2. Closing Remarks ------------------ The live question setup with stats on-screen is powered by Itempool. itempool.com/ Curious about other animations? 3blue1brown.com/faq#manim Music by Vincent Rubinetti. Download the music on Bandcamp: vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown Stream the music on Spotify: open.spotify.com/album/1dVyjwS8FBqXhRunaG5W5u If you want to contribute translated subtitles or to help review those that have already been made by others and need approval, you can click the gear icon in the video and go to subtitles/cc, then "add subtitles/cc". I really appreciate those who do this, as it helps make the lessons accessible to more people. ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted on new videos, subscribe: 3b1b.co/subscribe Various social media stuffs: Website: 3blue1brown.com Twitter: twitter.com/3blue1brown Reddit:

Why it's here

1 person recommends this, 1 disputes it

What people say. Recommended for building an intuitive understanding of complex numbers and exponentials, especially for applications like the Fourier transform.

rectangon Hacker News • Recommends

On “The Fourier Transform, explained in one sentence”

The key insight for me on this topic also came from 3Blue1Brown, but in a different video: it’s that e^x is NOT best thought of as repeated multiplication, but instead as the function exp(x) = 1 + x + x^2/2 + X^3/6 + x^4/24 + … After being relieved of the burden of that misconception, I was finally able to understand the role of complex numbers in the Fourier Transform. link to this video

rectangon Hacker News • Recommends

On “The Fourier Transform, explained in one sentence”

People told me that over and over but it didn’t help — because it didn’t make sense why repeated multiplication would cause rotation! Later in that video, we see a visualization of the rotation. I was able to grasp how the exp function could yield rotation where I’d never been able to understand why e*e*e*e… did. link to this video

rathelon Hacker News • Disputes

On “A Programmer’s Intuition for Matrix Multiplication”

True, but I don't agree with what he said here @ 8:00 link to this video Is this really the case? I checked Wikipedia and MathWorld and nobody makes a distinction between e^x and exp(x). Even if it's a "white lie" for didactic reasons, I don't buy it, it will be much more confusing down the line for students. Math is about finding structures governed by some rules and then generalizing them. To me the e^x defined as repeated multiplication conceptually is the same thing as the exponential function, just over broader domain. Why? You can interpolate between integer-valued X's using geometric mean. e^3 = sqrt(e^2 * e^4). What stops you from interpolating this recursively to achieve in the limit the expon…

beforeoliveson Hacker News • Mentions

On “Is Euler’s Identity Beautiful? and If So, How?”

I think that e^(i*pi) + 1 = 0 is massively overrated. Because the beauty that people find is largely based on the symbols that are present and because it doesn't really say anything meaningful beyond itself. It's not even a formula or an equation - it's a result. It's like being impressed by cos(pi) = -1. The more general formula e^(ix) = cosx + i*sinx is a lot more impressive. Both because of it's implications for the rest of mathematics and aesthetically. If you look at the way the vectors at 38:00-39:201 cancel out to always land on the unit circle - I can get behind calling that beautiful. 1 link to this video