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What Is the Fourier Transform?

(www.quantamagazine.org)
474 points rbanffy | 9 comments | | HN request time: 0.968s | source | bottom
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anyfoo ◴[] No.45133536[source]
If you like Fourier, you're going to love Laplace (or its discrete counterpart, the z transform).

This took me down a very fascinating and intricate rabbit hole years ago, and is still one of my favorite hobbies. Application of Fourier, Laplace, and z transforms is (famously) useful in an incredibly wide variety of fields. I mostly use it for signal processing and analog electronics.

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1. armanj ◴[] No.45134494[source]
Years ago, I often struggled to choose between Amazon products with high ratings from a few reviews and those with slightly lower ratings but a large volume of reviews. I used the Laplace Rule of Succession to code a browser extension to calculate Laplacian scores for products, helping to make better decisions by balancing high ratings with low review counts. https://greasyfork.org/en/scripts/443773-amazon-ranking-lapl...
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2. kragen ◴[] No.45135406[source]
While this is a good idea, I think it's unrelated to the Laplace transform except that they're named after the same dude?
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3. Shadowmist ◴[] No.45137382[source]
I always assume that all the ratings are fake when there is a low count of ratings since it is easy for the seller to place a bunch of game orders when they are starting out.
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4. CuriouslyC ◴[] No.45137527[source]
Just for reference, in case you find yourself in an optimization under uncertainty situation again: The decision-theoretic right way to do this is generate a bayesian posterior over true ranking given ranking count and a prior on true rankings, add a loss function (it can just be the difference between the true rating of the selected item and the true rating of the non-selected item for simplicity) then choose your option to minimize the expected loss. This produces exactly the correct answer.
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5. anentropic ◴[] No.45141378[source]
A bigger problem I find is many Amazon listings having a large number of genuine positive reviews, but for a completely different product than the one currently for sale.

Recently I was buying a chromecast dongle thing and one of the listings had some kind of "Amazon recommends" badge on it, from the platform. It had hundreds of 5 start reviews, but if you read them they were all for a jar of guava jam from Mexico.

I'm baffled why Amazon permits and even seemingly endorses this kind of rating farming

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7. armanj ◴[] No.45142183[source]
I referenced 3B1B for the name: youtube.com/watch?v=8idr1WZ1A7Q
8. yossarian22 ◴[] No.45148745[source]
Can you please provide an example or link to read more? Seems very interesting.
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9. kragen ◴[] No.45161050{3}[source]
https://en.m.wikipedia.org/wiki/Decision_theory