this post was submitted on 18 May 2024
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Science Memes

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[–] henfredemars@infosec.pub 46 points 6 months ago (3 children)

In computer engineering we have positive and negative zero.

[–] Gladaed@feddit.de 18 points 6 months ago (2 children)
[–] marcos@lemmy.world 4 points 6 months ago* (last edited 6 months ago) (1 children)

Unknowingly from the GP, that's exactly where CE got it from.

[–] Gladaed@feddit.de 3 points 6 months ago (1 children)
[–] marcos@lemmy.world 1 points 6 months ago

Grand parent / computer engineering

[–] Leate_Wonceslace@lemmy.dbzer0.com 4 points 6 months ago (3 children)

What algebra uses negative 0?

[–] agamemnonymous@sh.itjust.works 13 points 6 months ago (1 children)

When taking about limits, you can approach 0 from the positive or negative direction, which can give very different results. For example, lim cotx, x->0+ = ∞ while lim cotx, x->0- = -∞

[–] Leate_Wonceslace@lemmy.dbzer0.com 16 points 6 months ago (2 children)

Speaking as a mathematician, it's not really accurate to call that -0.

[–] agamemnonymous@sh.itjust.works 5 points 6 months ago

Yes, but it is infinitesimally close.

[–] Gladaed@feddit.de 1 points 6 months ago (1 children)

You also can't call something infinity. People call stuff names. It is just important that they define their terms well enough.

You also can't call something infinity

Why do you think that?

[–] barsoap@lemm.ee 7 points 6 months ago (1 children)

IEEE 754

I mean it's an algebra, isn't it? And it definitely was mathematicians who came up with the thing. In the same way that artists didn't come up with the CGI colour palette.

[–] Leate_Wonceslace@lemmy.dbzer0.com 1 points 6 months ago* (last edited 6 months ago) (3 children)

I'm not familiar with IEEE 754.

Edit: I think this sort of space shouldn't be the kind where people get downvoted for admitting ignorance honestly, but maybe that's just me.

[–] barsoap@lemm.ee 5 points 6 months ago* (last edited 6 months ago) (1 children)

It's a wonderful world where 1 / 0 is ∞ and 1 / -0 is -∞, making a lot of high school teachers very very mad. OTOH it's also a very strange world where x = y does not imply 1 / x = 1 / y. But it is, very emphatically, an algebra.

Mostly it's pure numerology, at least from the POV of most of the people using it.

I'll need to look at it more; it sounds interesting.

[–] Gobbel2000@programming.dev 4 points 6 months ago

IEEE 754 is the standard to which basically all computer systems implement floating point numbers. It specifically distinguishes between +0 and -0 among other weird quirks.

[–] barsoap@lemm.ee 2 points 6 months ago

You probably are familiar with the thing, just not under that name, and not as a subject of mathematical study. I am aware that there are, at least in theory, mathematicians never expanding beyond pen+paper (and that's fine) but TBH they're getting kinda rare. The last time you fired up Julia you probably used them, R, possibly, Coq, it'd actually be a surprise.

They're most widely known to trip up newbie programmers, causing excessive bug hunts and then a proud bug report stating "0.1 + 0.2 /= 0.3, that's wrong", to which the reply will be "nope, that's exactly as the spec says". The solution, to people who aren't numerologists, is to sprinkle gratuitous amounts of epsilons everywhere.

[–] Gladaed@feddit.de 2 points 6 months ago (1 children)

Math is more than just the set of all algebras.

[–] Leate_Wonceslace@lemmy.dbzer0.com 2 points 6 months ago* (last edited 6 months ago) (1 children)

I'm aware. Algebra is what I'm most interested in, and so when someone says "0" I think "additive identity of a ring" unless context makes the use obvious.

Edit: I've given it some thought, and I'm not convinced all algebras can fit in a set, because every non-empty set can have at least one algebra imposed upon them, and so the set of all algebras must have cardinality no less than the proper class of all sets. We also can't have a set of all algebras (up to isomorphism) because iirc the surreal numbers are an algebra imposed on a structure that itself incorporates a proper class, and is thus incapable of being a set element.

[–] barsoap@lemm.ee 1 points 6 months ago

Depends, I'd say. Is your set theory incomplete or inconsistent?

[–] HexesofVexes@lemmy.world 13 points 6 months ago

And, as a mathematician who has been coding a library to create scaled geometric graphics for his paper, I hate -0.0.

Seriously, I run every number where sign determines action through a function I call "fix_zero" just because tiny tiny rounding errors pile up in floats, even is numpy.

[–] PlexSheep@infosec.pub 13 points 6 months ago (5 children)

What do you mean? In two's complement, there is only one zero.

[–] yetAnotherUser@feddit.de 39 points 6 months ago

IEEE 754 floating point numbers have a signed bit at the front, causing +0 and -0 to exist.

[–] henfredemars@infosec.pub 18 points 6 months ago

Specifically I was referring to standard float representation which permits signed zeros. However, other comments provide some interesting examples also.

[–] sus@programming.dev 4 points 6 months ago
[–] hungrybread@hexbear.net 4 points 6 months ago (1 children)
[–] mexicancartel@lemmy.dbzer0.com 4 points 6 months ago (1 children)
[–] hungrybread@hexbear.net 2 points 6 months ago (1 children)

I assume no one at this point

[–] mexicancartel@lemmy.dbzer0.com 3 points 6 months ago

I think 1's complement only existed to facilitate 2's complement. Otherwise its stupid

[–] Zerush@lemmy.ml 2 points 6 months ago (1 children)
[–] PlexSheep@infosec.pub 2 points 6 months ago (1 children)

Floating point numbers are not possible in two's complement, besides that, what is your point? 0,99999999... is probably the same as 1.

[–] Zerush@lemmy.ml 2 points 6 months ago (1 children)

Yes, mathematically it's the same, but in physics there's a guy named Heisenberg who denies that 0.99999... really gets to 1. There is always this difference, for a mathematician infinite is not a problem, but for a physicist it is, plus a very big one.

[–] PlexSheep@infosec.pub 2 points 6 months ago

True, it sounds like that might be a problem if we consider that physics has to be between math and computer science.

(Have a nice day)