this post was submitted on 29 Sep 2024
187 points (96.1% liked)

Science Memes

11408 readers
2059 users here now

Welcome to c/science_memes @ Mander.xyz!

A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.

Rules

  1. Don't throw mud. Behave like an intellectual and remember the human.
  2. Keep it rooted (on topic).
  3. No spam.
  4. Infographics welcome, get schooled.

This is a science community. We use the Dawkins definition of meme.

Research Committee

Other Mander Communities

Science and Research

Biology and Life Sciences

Physical Sciences

Humanities and Social Sciences

Practical and Applied Sciences

Memes

Miscellaneous

founded 2 years ago
MODERATORS
[email protected]
[email protected]
[email protected]
187
u can just do stuff (mander.xyz)
submitted 2 months ago by [email protected] to c/[email protected]
10 comments fedilink hide all child comments
 
you are viewing a single comment's thread
view the rest of the comments
[–] Cawifre 30 points 2 months ago (1 children)

Please, could someone disect this frog for me?

[–] [email protected] 70 points 2 months ago* (last edited 2 months ago) (2 children)

https://en.m.wikipedia.org/wiki/Saddle_point

Basically, its a mathematical function where if you start at 0,0, you might falsely believe you are at the (or a) maximum or minimum of the function, as the slope at 0,0 is 0.

But, if you go any direction in the x axis, your function value rises, any direction in the y axis, your function value falls.

Thus a saddle point is an illusory, false impression of being at the extreme extent of a function, when in fact you are not.

The idea is that there is more to determining if you're truly at a global max or min of a function than only finding a single point where the slope is 0.

Edit: This comment if mine has been sitting at 69 upvotes for a few days now, so uh... obligatory joke about taste testing each others saddle points or something, I don't know.

[–] [email protected] 2 points 2 months ago* (last edited 2 months ago)

Hurr hurr, I'm gonna plot f(x,y)=x^2+y^3 where y=x for x limit inf. Checkmate science!

Edit: the graph isn't actually linear, man, and here I just thought it'd be that easy. :(

[–] rain_worl 0 points 2 months ago (1 children)

uhh, can't there be two local maxima that aren't saddle points? for example, x^2^-x^4^?

[–] [email protected] 1 points 2 months ago (1 children)

I mean ... sure?

Just have a continuous graph that looks like two little hills, but far away there is an even bigger mountain.

You'd then have two saddle points somewhere between those two little hills and the big mountain, though they might not be as visually distinctive as the image here.

Don't think I said you cannot have local maxima that are not saddle points.

Hell, even the image of the graph shown could be some kind of small scale topographically phenomenon, and what look to be going off to infinity in this small scope might actually top off as local maxima.

The actual function isn't shown.

It could be very simple, or it could be an absurdly complex polynomial that just looks like the simpler version when you zoom in.

Something like a 3d version of this:

[–] rain_worl 0 points 2 months ago (1 children)

thought you implied the local maxima were AT the saddle points

[–] [email protected] 2 points 2 months ago (1 children)

No, I explained what a saddle point is and how a saddle point can be misidentified as a local or absolute maxima or minima if all you do is look for a point where the slope is 0.

... anyway, is this a glitch on my end or ... how do most of your comments have 0 upvotes... and also 0 downvotes?

... I thought lemmy automatically gives every post 1 upvote by default.

[–] rain_worl 1 points 2 months ago (1 children)

you can remove your upvote, unlike reddit, where your vote doesn't count, just no votes display as a score of 1

[–] [email protected] 2 points 2 months ago (1 children)

... And you do this, manually, to all or almost all of your posts?

Or is your user account from an instance where that is done automatically?

[–] rain_worl 0 points 2 months ago

i do it manually :)