this post was submitted on 24 Aug 2024
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2d trulesformations (lemmy.blahaj.zone)
submitted 2 months ago* (last edited 2 months ago) by nicknonya@lemmy.blahaj.zone to c/196@lemmy.blahaj.zone
 
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[–] Ashelyn@lemmy.blahaj.zone 102 points 2 months ago (5 children)

The scaled down rectangle should be narrower; it's not scaled in this diagram, it's squished.

(Yes I know you can 'scale' objects on one axis but that's usually not how it's taught on an introductory level. Standard scaling assumes object similarity, which is not present in the diagram's 'scaled' rectangle.)

[–] Peppycito@sh.itjust.works 47 points 2 months ago

This is some quality pedantry.

[–] woodgen@lemm.ee 10 points 2 months ago* (last edited 2 months ago) (2 children)

Scaling in 2D has 2 parameters, X and Y, in the example X was at 1 while Y was below 1. You are referring to a subset of scaling transformation where X = Y and the aspect ratio is kept.

[–] Ashelyn@lemmy.blahaj.zone 12 points 2 months ago

Yes, and introductory geometry courses teach students how to do uniform scaling far before they teach them axis-based because it's better illustrative of the concepts of similarity and congruence

[–] shundi82@sh.itjust.works 4 points 2 months ago* (last edited 2 months ago)

And what about the arrow?

It's pointing down diagonally, which - at least to me (and for pretty much any GUI I can think of) - indicates, that it should be affecting both axes.

Then again, that whole illustration isn't all that great to begin with. So who knows, what that arrow is supposed to signify...

[–] Gobbel2000@programming.dev 5 points 2 months ago (1 children)

No, I wod say scaling is any diagonal matrix and thus even includes mirroring.

[–] Ashelyn@lemmy.blahaj.zone 1 points 2 months ago* (last edited 2 months ago)

Cool, now explain that to a class of 7th graders for me

edit: raised grade, it may been set a low but it varies. I think most kids start to learn this stuff in/around middle school

edit 2: also mirrored objects are generally considered similar so that's fine

[–] chad@sh.itjust.works 4 points 2 months ago* (last edited 2 months ago)

Ackchuawually, this example depicts a squish and a translation. A true scaling would have the scaling being done in place, resulting in an overlayed and smaller rectangle.

[–] germanatlas@lemmy.blahaj.zone 3 points 2 months ago

Damnit, I wanted to say that

[–] aeronmelon@lemmy.world 87 points 2 months ago (1 children)
[–] lugal@sopuli.xyz 25 points 2 months ago

I honestly needed this comment to get it

[–] spankinspinach@sh.itjust.works 39 points 2 months ago (2 children)

For the first time, I caught loss before loss was pointed out to me 😅

[–] tyler@programming.dev 6 points 2 months ago

Same lol. I hate this stupid meme, but I felt better about recognizing it in the wild.

[–] xantoxis@lemmy.world 31 points 2 months ago

In spring, a man plants a tree.
In summer, he plants another.
In the fall, they stood together.
In winter, one fell.

[–] alien@lemm.ee 18 points 2 months ago

IS THAT LOSS?!!

[–] someguy3@lemmy.world 12 points 2 months ago* (last edited 2 months ago) (2 children)

Rotation isn't even rotation which implies rotating around a point on that rectangle. That's rotation and translation. Such a loss.

[–] LMagicalus@discuss.tchncs.de 5 points 2 months ago

Rotation doesn't imply the point of rotation is on the rectangle.

[–] needanke 3 points 2 months ago

Scaling does not include translation either yet it does here by your logic.

[–] kittenzrulz123@lemmy.blahaj.zone 8 points 2 months ago