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[-] DigDoug@lemmy.world 12 points 7 hours ago

Practically everything people say about imaginary numbers you could also say about negative numbers.

Also... wrong about what?

[-] howdy@lemmy.ml 17 points 11 hours ago

men will invent new fields of mathematics before going to therapy

[-] SomethingBurger@jlai.lu 2 points 1 hour ago

Well, new fields of mathematics are useful.

[-] MonkderVierte@lemmy.zip 2 points 25 minutes ago

You imply that therapy is not.

[-] SomethingBurger@jlai.lu 1 points 6 minutes ago
[-] Agent641@lemmy.world 5 points 9 hours ago

All numbers are imaginary

[-] uriel238 4 points 10 hours ago

This is a thing that mathematicians do. Rather than just assume you can't divide by zero they'll go ahead and try and see what happens.

[-] davad@lemmy.world 68 points 17 hours ago

I've always thought "imaginary" vs "real" was an unfortunate naming convention.

I don't know about other fields, but electrical engineering uses imaginary numbers with AC circuits and changing electrical fields. Since electricity moves as waves, imaginary numbers let you represent what's coming 90 degrees later in a compact way.

[-] a1tsca13@lemmy.world 6 points 8 hours ago

And in optics, the "real" portion of a material's refractive index represents scattered light and the "imaginary" part represents absorbed light.

[-] iusemybrain@sh.itjust.works 16 points 12 hours ago* (last edited 12 hours ago)

don't forgot signal processing. Complex number theory is used a lot when it comes down to Fourier transforms of discrete or continuous functions.

but yea the naming convention of "imaginary numbers" is pretty bad, we did the same thing for negative numbers (we called it imaginary) when people couldn't comprehend of a negative quantity.

negative numbers are defined from a conservative system, basically a gain/loss relationship: if I have 2 apples and I give away 1 to a friend, I have 1 apple left, that loss -- that apple I gave to a friend -- is the negative quantity. For imaginary numbers, we don't really have a way to comprehend an imaginary quantity; what does it mean that I have sqrt(-1) apples.

[-] Malfeasant@lemmy.world 1 points 1 hour ago

It means you have an orange.

[-] socsa@piefed.social 4 points 11 hours ago

Right, it's just an orthogonal basis. You can extend this to many dimensions, fields and geometries.

[-] FishFace@piefed.social 25 points 17 hours ago

Yeah, I think it causes unnecessary difficulties. I actually think they're introduced at a time when you could instead teach them as two-dimensional vectors with pointwise addition and a special multiplication and division rule, and prove that (0, 1)×(0, 1) = (-1, 0) using that rule, so that sqrt(-1, 0) = (0, 1).

Then you can establish a convention that you write (a, b) as a + bi (and i = (0, 1)).

This is too abstract for younger students, but nowadays I don't think they learn complex numbers anyway, and I think it would be less spooky for the older students.

[-] andros_rex@lemmy.world 3 points 9 hours ago

Imaginary numbers are typically introduced in a high school “algebra 2” course in my neck of the woods, like junior year unless you are accelerated or held back. I feel like it’s really common for them to not be taught well - the naming is something that occasionally trips up the teachers.

The teaching of them is something that really interests me - they’re the kind of thing that triggers the “when am I ever going to use this?”/rants about not learning how to do taxes. You can talk about the relevance to electronics, but DC electronics is already hard enough for most to comprehend.

I like to connect it to rotation. Show them the pattern of powers of i with physical movement - quarter turns.

[-] FishFace@piefed.social 2 points 9 hours ago

Yeah. I think the vectors-first approach allows you to get straight to rotations, too.

[-] andros_rex@lemmy.world 1 points 7 hours ago

The big thing is that vectors seem to be the kind of “shoved into the end of the semester if there’s time after testing” from what I’ve seen. Most of the time, even when I work with calculus students they have no idea what a vector is.

A big thing to is getting them to understand what square roots even really mean. I’ve noticed a lot of students struggle with getting sqrt(x) * sqrt(x) = x, so even just the simple “hey, can you get a negative by taking a number and multiplying by itself?” is often a hurdle cognitively. (A lot of this I suspect has to do with not understanding what multiplication or division really “are” - I usually remediate with the area model)

[-] FishFace@piefed.social 1 points 19 minutes ago

Wow, (potentially) omitting vectors seems like a big gap. Obviously it has huge direct practical use, but it's probably also the first introduction to how you can take a structure and augment it with operations. In that way it's the first step on the road to abstract mathematics.

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[-] IAmNorRealTakeYourMeds@lemmy.world 9 points 17 hours ago

Not just electricians.

3d graphics are all about about quaternions (4d version of imaginary numbers).

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[-] Klear@piefed.world 106 points 19 hours ago

It's more complex than that...

[-] devaly@ani.social 47 points 19 hours ago
[-] LemmyPlaceDN@europe.pub 20 points 18 hours ago

Think rationally

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[-] NaibofTabr@infosec.pub 48 points 18 hours ago* (last edited 18 hours ago)

Just one more axiom bro and it will all make sense... just one more I swear it's consistent... BRO I just NEED one more conjecture and it will BE complete... tHe pRincIPles ARe sOLid BrO jUST TruST mE!

[-] yesman@lemmy.world 41 points 19 hours ago

It's not like the regular numbers behave themselves. Have you ever heard a coherent, non-self referential definition of the number 3?

[-] MonkderVierte@lemmy.zip 1 points 1 minute ago
[-] ivanafterall@lemmy.world 3 points 11 hours ago

Yes. In fact, just earlier today, my buddy Darryl was telling me about a coherent, non-self preferential definition of the number 3. It's not a big deal. People do that stuff all the time.

[-] arctanthrope@lemmy.world 20 points 18 hours ago

the only numbers that actually exist are 0 and 1. everything else is a reference to those

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[-] gezero@sopuli.xyz 19 points 19 hours ago
[-] protist@retrofed.com 9 points 16 hours ago
[-] Axolotl_cpp@feddit.it 2 points 11 hours ago* (last edited 11 hours ago)

So, take 2 bananas and add 1 banana

[-] protist@retrofed.com 3 points 9 hours ago
[-] Axolotl_cpp@feddit.it 1 points 1 hour ago

A banana is an elongated, edible fruit that is botanically a berry produced by several kinds of large treelike herbaceous flowering plants in the genus Musa.

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this post was submitted on 02 Aug 2026
703 points (100.0% liked)

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