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submitted 1 month ago* (last edited 1 month ago) by nicknonya@lemmy.blahaj.zone to c/196@lemmy.blahaj.zone

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[-] Ashelyn@lemmy.blahaj.zone 101 points 1 month ago

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 46 points 1 month ago

This is some quality pedantry.

[-] woodgen@lemm.ee 10 points 1 month ago* (last edited 1 month ago)

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 1 month 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 1 month ago* (last edited 1 month 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 1 month ago

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

[-] Ashelyn@lemmy.blahaj.zone 1 points 1 month ago* (last edited 1 month 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 1 month ago* (last edited 1 month 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.