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The unreasonable effectiveness of the Fourier transform

joshuawise.com

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Re: The unreasonable effectiveness of the Fourier transform

#71

Post by zamadatix »

javawizard wrote: post #53
Chrupiter wrote: post #48

Earlier quoted context omitted.

I don't think pulsing skin (due to blood flow) is visible from a webcam though.

Plenty of sources suggest it is: https://github.com/giladoved/webcam-heart-rate-monitor https://medium.com/dev-genius/remote-heart-rate-detection-us... The Reddit comments on that second one have examples of people doing it with low quality webcams: https://www.reddit.com/r/programming/comments/llnv93/remote_... It's honestly amazing that this is doable.

My dumb ass sat there for a good bit looking at the example in the first link thinking "How does a 30-60 Hz webcam have enough samples per cycle to know it's 77 BPM?". Then it finally clicked in my head beats per minute are indeed not to be conflated with beats per second... :).

Non-paywalled version of the second link https://archive.is/NeBzJ

Re: The unreasonable effectiveness of the Fourier transform

#72

Post by bobbylarrybobby »

fracus wrote: post #64

Learning about the Fourier Transform in my Signals and Systems class was mind opening. The idea you can represent any cycling function with sinusoidal functions would not only never occur to me but I would have said it wasn't possible.

And even non cycling functions (e.g. a gaussian)

Re: The unreasonable effectiveness of the Fourier transform

#74

Post by alden5 »

This talk was given at crowd supply’s 2025 teardown convention which after going for the first time last year I highly recommend it to anyone interested in hardware development. Met a lot of super cool people and managed to get my ticket price back 4x in the amount of free dev boards I got lol

Re: The unreasonable effectiveness of the Fourier transform

#75

Post by ggm »

cogman10 wrote: post #37
pastrami_panda wrote: post #26

Earlier quoted context omitted.

Gauss's notes and margins is riddled with proofs he didn't bother to publish - he was wild. Not sure if true, but allegedy he insisted his son not go into maths, as he would simply end up in his father's shadow as he deemed it utterly Impossible to surpass his brilliance in maths :'D

> as he would simply end up in his father's shadow as he deemed it utterly Impossible to surpass his brilliance in maths Definitely true but also bad parenting. Gauss was somewhat of a freak of nature when it came to math. Him and Euler are two of the most unreasonably productive mathematicians of all time.

But what he deemed being posited as true, was this really bad parenting? It could be to head off competition or it could be brutal realism to head off future depression.

Nepotism existed since time immemorial but for a mathematical genius, what was the nepotistic deliverable for the child? A sinecure placement at university?

Re: The unreasonable effectiveness of the Fourier transform

#77

Post by wolfi1 »

brcmthrowaway wrote: post #31
derektank wrote: post #23

My favorite story about the Fourier Transform is that Carl Friedrich Gauss stumbled upon the algorithm for the Fast Fourier Algorthim over a century before Cooley and Tukey’s publication in 1965 (which itself revolutionized digital signal processing).[1] He was apparently studying the motion of the asteroids Pallas and Juno and wrote the algorithm down in his notes but it never made it into public knowledge. [1] http…

How was Gauss so productive with 6 children?

no TV

Re: The unreasonable effectiveness of the Fourier transform

#78

Post by refulgentis »

ggm wrote: post #75
cogman10 wrote: post #37

Earlier quoted context omitted.

> as he would simply end up in his father's shadow as he deemed it utterly Impossible to surpass his brilliance in maths Definitely true but also bad parenting. Gauss was somewhat of a freak of nature when it came to math. Him and Euler are two of the most unreasonably productive mathematicians of all time.

But what he deemed being posited as true, was this really bad parenting? It could be to head off competition or it could be brutal realism to head off future depression. Nepotism existed since time immemorial but for a mathematical genius, what was the nepotistic deliverable for the child? A sinecure placement at university?

It’s unusual to tell others not to do something because you’re projecting they’re secretly doing it to compete with you, or that they’ll be depressed when they don’t do what you did.

Doubly so when the rationale is “I’m so fucking awesome”

Triply so when it’s something you’re passionate about, presumably inherently.

Quadruply so when it’s your child. Its tough as a kid hearing your parents come up with elongated excuses why you can’t dream and work towards a future.

When you let people find their own way, you might even learn something from it (ex. 70 yo Gauss learns he didn’t need to tie his mental state to his work because his son doesn’t suddenly become depressed from not matching dads output)

Re: second half, sounds about right, confused at relevancy though (is the idea the child would only do it to pursue nepotistic spoils and an additional reason is the spoils aren’t even good?)

Re: The unreasonable effectiveness of the Fourier transform

#79

Post by bschwindHN »

Jun8 wrote: post #58

A signal cannot be both time and frequency band limited. Many years ago I was amazed when I read that this fact I learned in my undergraduate is equivalent to the Uncertainty Principle! On a more mundane note: my wife and I always argue whose method of loading the dishwasher is better: she goes slow and meticulously while I do it fast. It occurred to me we were optimizing for frequency and time domains, respectively,…

> I was minimizing time so spent while she was minimizing number of washes

I'm probably just slow, but I'm not following. Do you mean because you went fast, you had to run another cycle to clean everything properly?

If you haven't already, you should watch the Technology Connections series on dishwashers.

https://www.youtube.com/watch?v=jHP942Livy0

Re: The unreasonable effectiveness of the Fourier transform

#80

Post by defrost »

brcmthrowaway wrote: post #31
derektank wrote: post #23

My favorite story about the Fourier Transform is that Carl Friedrich Gauss stumbled upon the algorithm for the Fast Fourier Algorthim over a century before Cooley and Tukey’s publication in 1965 (which itself revolutionized digital signal processing).[1] He was apparently studying the motion of the asteroids Pallas and Juno and wrote the algorithm down in his notes but it never made it into public knowledge. [1] http…

How was Gauss so productive with 6 children?

I'd hazard by not dealing with them until they'd been schooled enough to operate as computers and GI (general intelligence) assistants.

There's a spread of farmers, railroad and telegraph directors, high level practical infomation management skills in the children.

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