#serious-discussion

1 messages · Page 79 of 1

tacit tulip
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nice

surreal sapphire
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once its published, come back

tacit tulip
#

good for u

frail snow
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Only over function fields though

alpine kindle
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<@&268886789983436800>

mental stratus
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wtf fuck off

upbeat shore
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@cold needle

neat lintel
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alright @mint patio

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it's easiest to start with the inverse function theorem

mint patio
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I wrote what I interpreted kekw then got told it was kinda wrong immediately after

neat lintel
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i can look after

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food is consumed

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username attained

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ready to game

mint patio
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let us game son I’m ready to learn

neat lintel
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the inverse function theorem is basically: if the best linear approximation at a point to a function is invertible, then the function is locally invertible around the point

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why is this plausible

mint patio
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I can give you an intuitive answer but not a formal one lol

neat lintel
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well the best linear approximation at p is the linear map Df(p)

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and what that means is f(x) = f(p) + DF(p)(x - p) + o(x - p)

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o(x - p) meaning terms going to zero faster than x - p does

mint patio
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Mhm

neat lintel
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these are negligible if you get reeeealll close to p

mint patio
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Yep

neat lintel
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so rrrreeeeeeallll close to p you have f(x) = f(p) + DF(p)(x - p)

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not = but you know

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squiggly equals

mint patio
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Yes

neat lintel
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well when is this simpler guy invertible

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when DF(p) is

mint patio
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ayaya

neat lintel
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so if f(x) ≈ f(p) + Df(p)(x - p) then you would expect to have something like f^{-1}(y) ≈ p + DF(p)^{-1}(y - f(p))

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did i get that one right lemme look

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yeah

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please forgive me using f and F interchangeably

mint patio
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mfw I didn’t even notice (I am converting mentally 🤓)

neat lintel
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some harder thinking and you might even say f^{-1}(y) = p + Df(p)^{-1}(y - f(p)) + o(y - f(p))

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the actual proof of the inverse function theorem, at least the one in spivak, is just making sure you can actually go from "really close to invertible map" to "invertible map"

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implicit function theorem

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the corresponding linear algebra thing is solving systems like Ax + By = 0 for y in terms of x

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why

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well say you have a nonlinear system of equations f(x, y) = 0 and you want y in terms of x near a point (a, b)

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when you take the linear approximation at (a, b) you'll get a linear system of equations (a breeze to solve. so easy)

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f_x(a, b)(x - a) + f_y(a, b)(y - b) = 0

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i probably should have mentioned i wanted B to be square

mint patio
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any determinant needers in the chat

neat lintel
neat lintel
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solve.

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to get y in terms of x you need f_y(a, b) to be invertible

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the implicit function theorem says that, if you can solve this approximating linear system, then you can solve the non-linear system locally

mint patio
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I sort of see why they’re the same

neat lintel
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in linear algebra, invertibility of a matrix and the condition of whether you can solve a system of equations involving the matrix are the same

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so of course the theorems in calculus should be the same!

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proof: just try to adapt the linear algebra proof to calculus

mint patio
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I never really learned rank stuff properly so that’s the one I don’t know or understand

neat lintel
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if the rank of a matrix is r then it can be put into the form

I_r  O
O    O
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I_r the r by r identity matrix

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this is the only fact you need to know for the constant rank theorem

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(the Os may be of different sizes but they're all just matrices with only zeros)

mint patio
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Yes

neat lintel
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so well

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you can probably guess how it's going to go

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if a mapping's best linear approximation looks like this I_r OOO thing then the function ought to look like it locally

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there is one small issue

mint patio
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I’m guessing it’s just if constant rank within nbhd then you guarantee invertibility within nbhd

neat lintel
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not invertibility

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constant rank applies to maps from any R^m to any R^n

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but yes constant rank is the condition

mint patio
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If the differential isn’t square?

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but isn’t that related to invertibility

neat lintel
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only square ones can be invertible, and, in that case, invertibility is the same thing as maximal rank

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anyways

neat lintel
# neat lintel there is one small issue

if the mapping looks like this, i.e. looks like (x_1, ..., x_m) -> (x_1, ..., x_r, 0, ..., 0), then that forces its derivative to have rank r not just at one point, but near the point you were considering

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so constant rank is a necessary condition for the result to hold

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it is also sufficient. cool

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because a matrix has rank at least r if it has a non-vanishing r by r minor, the rank of a matrix cannot drop suddenly

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so you just have to make sure that the rank isn't jumping near your point

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in particular if you have maximal rank at the point you have maximal rank near the point

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this is how you get the inverse function theorem out of this

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when square maximal rank is equivalent to invertibility

mint patio
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ahh ic

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that one’s cooler than the other two

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maybe that’s bc I’m less familiar with it though 😛

neat lintel
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so true

mint patio
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Thank you for explaining

neat lintel
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tu's manifolds book has an appendix going over all of this

mint patio
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I don’t think I’m ready for this subject

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I mean I understand the concepts, I’m just an absolute Cox-Zucker when it comes to proofs and manipulating objects lol

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but ig that means I don’t understand very well huh? kekw

molten ibex
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why chatgpt chan nit solve elementary algebra problems?

mint patio
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bc it sucks for math

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use a CAS

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It’s a text generator

molten ibex
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cas is artificial inteligence?

mint patio
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As in Computer Algebra System

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Wolfram, Sage, MATLAB, etc

languid marten
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ChatGPT is good with providing correct definitions but can't do even simple arithmetic correctly

mint patio
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Funny enough

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it helped me a lot with my fluids hw

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LOL

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I had it solve some NS for me kekw

neat lintel
mint patio
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just ignore viscous terms

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easy 👍

neat lintel
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i saw someone try to ask it what the third isomorphism theorem was and it produced a blatantly wrong statement

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literal nonsense

languid marten
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yeah it does some errors in defn as well but not as much as in computations

mint patio
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the third isomorphism theorem according to chatgpt

languid marten
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isn't stokes thorem or generalized stokes thm

mint patio
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just call it stokes

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generalized stokes if you want to be specific ig kekw

languid marten
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yeah

mint patio
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That’s Stoke’s Theorem yeah

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Man I remember

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When I learned it the first time (or Kelvin-Stokes, rather)

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And Moth was explaining the intuition to me here

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That feels so long ago but also just like yesterday

alpine comet
mint patio
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That’s Yoneda’s lemma, excuse you

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according to ChatGPT at least devilish

languid marten
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you can convince chatgpt into believing anything

alpine comet
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Even if ChatGPT gets better at math, I will still study math tbh

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There's no good if I can't verify if a proof is correct

neat lintel
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<@&268886789983436800>

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"frist trun off your antivirus"

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any mods online

livid gull
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It doesn't have any intuition

alpine comet
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It doesn't need intuition

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Math a lot of times boils down to knowing and applying tricks

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And AIs are way better than us when it comes to that. Just look at AlphaZero

neat lintel
languid marten
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does it mean it will not be able to come up with "new" proofs ever ?

alpine comet
languid marten
alpine comet
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There will be no algorithms for it tho KEK

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At the very end of the day, it's a hell lot of knobs being tuned just right so that it stumbles upon something

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I think there's technically an algorithm to generate proofs: just enumerate all possible combinations of logic symbols. But it's so useless that you better just study math and do the proofs yourself

languid marten
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hmm Can we solve open problems with AI somehow ?

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like using that algirothm of enumerating all possible combinations of logical symbols

alpine comet
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We did solve open problems with computers before

languid marten
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hmm but mostly using it's computational powers ?

alpine comet
languid marten
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like how does it get to the "correct" proof

alpine comet
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You don't

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that's the point of halting problem: you can't decide if a given program halts

alpine comet
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but there are statements that are correct but not provable

languid marten
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So the task is to prove that it's unprovable within the given axiomatic system

alpine comet
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We don't know 😄 we haven't found any statements like that

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We know they exist tho

languid marten
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CH ?

alpine comet
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Nah, We proved that one is independent

languid marten
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ig it's proven to be unprovable

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ohh yeah independent of zfc

alpine comet
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Godel's first incompleteness theorem implies that for any such consistent formal system, there will always be statements about natural numbers that are true, but that are unprovable within the system.

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I think the second theorem shows that the consistency of the system is such a statement

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either a system is inconsistent, then it's demonstrable, or it's consistent, but it cannot proves the consistency of itself

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Idk, I don't study logic. And for good reasons

languid marten
alpine comet
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They apply to all domains in math KEK

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You don't have to extend anything

languid marten
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hmm then why godel's 1st incompleteness thm talks about natural numbers specifically

alpine comet
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It's the weakest system you can possibly hope for

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Anything below that is too weak to be interesting

languid marten
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ohh yes So it's godel's weak thm KEK

neat lintel
sudden thunder
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Can anybody help me take this godforsaken calculator off test mode i'm about to claw my eyes out

neat lintel
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what calculator is it

sudden thunder
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yes cs ii t

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i have the application

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windows is recognising the calculator

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but the application isn't

woven whale
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I usually just use another calculator of the same model

sudden thunder
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do you work for texas instruments and want me to purchase another calculator?

woven whale
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Yes

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do you like not

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have anyone at school that has the same calculator as you

sudden thunder
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i graduated

woven whale
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skill issue

neat lintel
sudden thunder
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thank you both this has been enlightening

neat lintel
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if your only problem is getting it out of test mode there should be plenty of help online

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could you not find anything?

sudden thunder
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well my problem is that this is happening

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getting it out of test mode should be fine assuming the app they made for it works

neat lintel
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oh

sudden thunder
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the only way to do it through a computer involves TI Inspire Computer Link

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i have my calculator plugged into the computer

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the computer is turned on since i'm using it to send these messages

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and windows recognises it as a TI Inspire CX II-T

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but somehow the app can't see it

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oh god. i just realised that the free app doesn't work with my calculator and that I have to buy the student software

eternal glen
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Texas instruments my beloathed

sudden thunder
storm sage
solar hawk
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english totally robbed latin for like half of its (english's) words

bronze pelican
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@solar hawk what does your name mean

solar hawk
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Is it partially made of my initials though

bronze pelican
#

Amukh

solar hawk
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I would explain but I don’t wanna dox myself 😭

bronze pelican
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Don't

echo tundra
echo tundra
solar hawk
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lol

echo tundra
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thanks xD

solar hawk
echo tundra
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I mean north languages are pretty similar so not a big coincidence

solar hawk
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ig

jovial ember
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Chmonkey

fervent seal
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im back

neat lintel
jovial ember
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Hi pikachu

jovial ember
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Lol “bohneur”

bright hill
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chmonkey french pilled

jovial ember
#

No it’s in the name of the gif they sent

long matrix
echo tundra
bright hill
bright hill
echo tundra
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@bright hill hello, just want to talk about the custom server

rocky shuttle
long matrix
hollow widget
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yo guys i really need hhelp
i have a finaly exam after tmrw
and i cant find my geomerty book
its called "geometry 2018 student edition"
if anyone has it please dm me

river moon
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search up Pontryagin

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the dude was blind from like the age of 14 and has quite a bit of theorems named after him

alpine kindle
#

mathematics is, with one viewpoint, entirely abstract so yes probably

zealous garden
#

That's how computers do it

little vine
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Is Euclid the best Geometry book? Not for someone in junior high but for an older student/mathematician who'd care to learn it for some unknown reason

solid yarrow
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Any recommendation which book I should get, after the "Book of Proof" in terms of preparation for university?

solid yarrow
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I read the discription. Sounds quite interesting.

mental stratus
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and gallian for aa

solid yarrow
mental stratus
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abstract algebra

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axler for linear algebra is good too

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these three are like classic recs for anyone begin the next step

solid yarrow
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So for abstract algebra gallian, analysis terence tao and linear algebra axler?

vast surge
solid yarrow
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I am not so sure if I get them through till uni starts 😦

vast surge
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Axler is not a good book. Determinants are an important part of LA, and his "determinant-free" approach is mind-boggling.

solid yarrow
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So I should swap axler with pinter?

vast surge
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Swap axler for ladw

solid yarrow
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Ladw?

vast surge
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I like Pinter better than Gallian for the exercises, but I think Gallian is fine

vast surge
bronze pelican
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Axler is good

vast surge
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Except for how he does determinants.

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In the very last chapter

river moon
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"determinants are an important part of LA" smugCatto

vast surge
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They are!

solid yarrow
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Ok quick question. What do you think about the "Book of Proof"? For introduction purposes.

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Bc I am currently reading it.

vast surge
solid yarrow
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So useful?

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for uni

vast surge
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It's useful

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Axler does eigenvalues and eigenvectors before he does determinants though

river moon
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sully now that's sus

vast surge
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Yeah

solid yarrow
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The questions is, am I able to work through those books till uni or even do I have to?

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kind of worried

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a bit

vast surge
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Those are all textbooks for courses you're expected to take in your first year or so

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If you're American you might take 3 years going through them. If you're a Brit it might just be your first year.

solid yarrow
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So it's supporting material after the courses?

vast surge
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No, it's the textbook for the course.

vast surge
solid yarrow
#

Thats new

vast surge
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Yes.

solid yarrow
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Interesting.

vast surge
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You need to read the textbook as well as attend lectures

solid yarrow
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Are solutions in the books?

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Or do you get solutions?

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Or something alike

vast surge
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Generally there are not solutions to exercises in textbooks at this level

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I think Pinter includes some hints

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And solutions to very simple computational problems

solid yarrow
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So how you does one find out if you he's right?

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guess work?

vast surge
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You generally know.

solid yarrow
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ok

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Man I wish I could do more advanced math... I find those topics I see around so interesting. And then I realize that I am not even at the beginning.

vast surge
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Just start studying and keep studying and you'll get there

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I'm starting my PhD in a couple months and I'm still just starting off in math

solid yarrow
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What topic?

vast surge
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Mathematics.

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I'm not sure anything more specific than that yet

solid yarrow
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Hm.

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What does a math PhD do?

vast surge
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Math

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I'm going to be grading probably calculus

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And taking advanced courses

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Then in a couple years doing research

solid yarrow
#

What do you do in calculus?

solid yarrow
vast surge
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I will probably have a discussion section, and then I will grade homework.

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That is my guess.

solid yarrow
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Hm.

vast surge
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Unless you mean, like, what is calculus

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In which case it's calculating derivatives and integrals

solid yarrow
#

That would have been my guess.

vast surge
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So in calculus you learn to compute things like this integral: $\int_{0}^{1}x,dx=\frac{1}{2}$

fathom swallowBOT
#

Zorn's Lemming

solid yarrow
#

With compute, you mean what exactly? Typing it in a program?

vast surge
#

Calculate

solid yarrow
#

Hm.

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That's what I have been taught at school.

vast surge
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Yes, the American curriculum is a bit slower.

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Lots of people don't see calculus until they start college

solid yarrow
#

Ok. In Germany we see integrals in "Gymnasium". I don't know the correct school system, so...

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But it is the "highest" school, but still under university.

bronze pelican
vast surge
vast surge
solid yarrow
#

I am still wondering which books I will have to buy when i enroll uni.

vast surge
#

It depends a lot on the professor teaching the course

solid yarrow
#

Because it could become a problem, if i buy a book which i then won't use.

vast surge
#

At my UG some professors used Pinter, some used Gallian when teaching algebra

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It depends on who's teaching it when

solid yarrow
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so i should wait with buying?

vast surge
#

Buy if you want to self-study before you start

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If you only want the books you'll use in your courses, then wait

solid yarrow
#

i mean i want to study math, but i am worried that i might buy books that i will later on not use. i mean i only have a few months till uni, so...

vast surge
#

Then finish reading book of proof now

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What math courses are you in next semester?

solid yarrow
#

I am at the last big chapter.

solid yarrow
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Propably linear algebra, i guess.

woven whale
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linear algebra 1 and analysis 1 is the standard for first sem in germany

vast surge
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LADW is free on the internet.

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Read that

woven whale
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maybe also an intro to programming

vast surge
woven whale
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Yes

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at least at my uni you are required to take analysis 1, 2, 3 which includes measure theory and analysis on manifolds

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and algebra 1 is optional

vast surge
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Oh, wow.

solid yarrow
#

?

vast surge
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That is a very strong analysis bias

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What do the germans who want to do algebra do?

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Suffer?

woven whale
#

you can take like numerical analysis instead of algebra 1 lol

woven whale
vast surge
#

Maybe

woven whale
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my uni has a big numerical department

vast surge
#

Ah that makes sense then

solid yarrow
#

Do you get books recommended by your prof? Like at the beginning of your courses?

woven whale
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yeah profs usually give literature recommendations

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or say what book they are basing their course off

solid yarrow
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i like the approach, idk why though

vast surge
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Do you have any German textbooks or do you just use the popular ones in English?

woven whale
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I have this one german category theoretical algebraic geometry textbook

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and one on numerical analysis

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but nowadays I just use online pdfs

solid yarrow
woven whale
#

first book of the bible in your favorite library...

solid yarrow
#

?

vast surge
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Ahoy, maties! Walk the plank! Arr!

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That's how to get free pdfs.

solid yarrow
#

But you need to sign up.

woven whale
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usually I just search for "<book title> pdf" though lol

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fwiw you can log in with your uni account on springer and get books that your uni purchased

solid yarrow
#

hm

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Do you keep notes of those books? Or do you just do the problems?

woven whale
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I do notes if I feel like it

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or if I can't ctrl + f the book

solid yarrow
#

So in general just the problems.

woven whale
#

wait you guys do the problems? opencry

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I just play spectator

solid yarrow
#

but if the pdf is longer than 100 pages, how do you keep track where you left off?

woven whale
#

I use obsidian to read pdfs

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if you close the app on page 69420 then next time you open it again it will resume on page 69420

solid yarrow
#

is it free?

woven whale
#

yes

solid yarrow
#

interesting

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Got any more tips I need/ should know before uni?

woven whale
#

git gud

solid yarrow
#

that was the plan

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xD

solid yarrow
mental stratus
#

yep

solid yarrow
#

k thanks

mental stratus
#

Heard good things about it

livid gull
#

i feel like uni is needlessly hard in germany

velvet dagger
#

How have your opinions gotten that bad

neat frost
woven whale
mint patio
#

@storm sage what’s your youtube channel

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also I’m going to get you to help me learn algebra

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also also I think I’m going to become algebra pilled just so I can get away from point set topology

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@woven whale I like projective :3

woven whale
mental stratus
#

about me

mint patio
#

I forgor my MineCraft account :sadge:

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Maybe once I’m a big boye and can play games as much as I want

storm sage
#

I wanna learn numerical analysis 🥺

storm sage
storm sage
mint patio
neat lintel
#

what is wrong with point-set topology?

mint patio
#

open and closed sets

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why’s there gotta be two :sadge:

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and then there’s CLOPEN too like wat the fuck

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it’s that hitler video all over again

neat lintel
#

this really isn't that confusing

mint patio
#

why can’t there just be

#

set

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(excluding category theory fuck that too)

mint patio
neat lintel
#

most of basic point-set topology is supposed to be incredibly straightforward

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it's good proof writing practice

mint patio
#

shh let me whine in peace I’ll come back to it one day :3

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I do the algebraic analysis 👍

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become new eric tao

neat lintel
#

if you do commutative algebra you are going to have to grapple with open and closed sets

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if you do analysis you are going to have to

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like

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this isn't really something you can reasonably avoid

mint patio
#

yes I know :hehe: but it’s so much easier than the spaghetti that goes on in m*nifolds

jovial ember
#

They’re all the same thing

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Bruh

neat frost
jovial ember
#

This is like saying there’s blue and not blue

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I guess not the perfect analogy

solid yarrow
#

What is LaTeX? Have only heard of it.

neat frost
#

It's a language for typesetting documents

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It has very tools for typesetting math and so is very popular in academia

solid yarrow
#

Do you learn that in university?

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I mean like writing it

neat frost
#

you learn it yourself

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idt unis usually provide a course on it

solid yarrow
#

do you need a specific program for it?

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to write it

leaden torrent
#

no, its a language

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so you need a program or software to compile it

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but you can write it with any text editor

solid yarrow
leaden torrent
#

like how you can write C++ in any IDE, but you need gcc or something to compile it

solid yarrow
#

like vscode?

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or something similar?

leaden torrent
#

sure

#

there are dedicated latex editors though

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but again those dont usually come with a compiler

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the standard latex distros on windows are miktex and texlive

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idk about other platforms

#

and then you can write it in whatever text editor you prefer, though there are dedicated latex editors (e.g. texstudio)

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there's also overleaf, an online latex editor

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good for collaboration on the same document

solid yarrow
#

what would be your recommendation?

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like for an absolute beginner

neat frost
#

vim+TeXlive is the way to go

leaden torrent
#

personally i use miktex + texstudio

neat frost
leaden torrent
#

but overleaf is the most beginner friendly

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no need to install anything

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it holds your hand a lot

solid yarrow
#

might give it a try in the future.

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by the way... i was wondering about implications. Why does math have two symbols for that? Like an single arrow and a double arrow?

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Are they used in different ways?

neat frost
#

like $\rightarrow$ vs $\Rightarrow$?

fathom swallowBOT
solid yarrow
#

yes

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exactly

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where's the difference?

leaden torrent
#

just down to the preference of the author

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no real difference

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anecdotally $\rightarrow$ feels more common among philosophers and logicians, and $\implies$ feels more common in most other settings

fathom swallowBOT
#

namington

neat frost
#

Though single-stroke arrows are used for many other things in math as well, so double-stroked arrows stand out more

leaden torrent
#

yeah i personally prefer \implies since its less likely to get confused

woven whale
leaden torrent
#

$\exists f^{-1}\colon ℝ \to ℝ \implies f$ is bijective

woven whale
#

no

fathom swallowBOT
#

namington

woven whale
#

wait people use rightarrow for implies Lmao

solid yarrow
#

so in general use the double arrow, just to make sure.

#

for implications

leaden torrent
#

yeah, ive only really seen the single arrow used in the context of formal logic or philosophy

#

(and in formal logic its because theres often a distinction between syntactic and semantic implication)

solid yarrow
#

Good to know.

#

Hopefully my uni also provides that.

#

When I am enrolling.

woven whale
#

what uni will you be going to?

solid yarrow
#

Still not so sure.

neat frost
#

I think LaTeX is not too hard to self-learn

solid yarrow
#

Or in other words, complex.

neat frost
#

it is very different from html

#

for one it is not stupid

#

and its meant for typesetting documents, not webpages

fathom swallowBOT
#

pikachupikachu

solid yarrow
#

But I guess that comes with practice and stuff.

neat frost
#

everyones new before they learn something

solid yarrow
#

true

neat frost
#

read a few tutorials and whatnot

solid yarrow
#

any recommendation?

neat frost
#

sure

#

,help tex

fathom swallowBOT
#
`tex` command documentation. (Aliases `,`, `mtex`, `align`, `latex`, `texsp`, `texw`, `tikz`.)
Usage

,, <equations>
,tex <code>
,align <align block>
,texsp <code>
,texw <code>
,tikz <code>

Description

Compiles and displays LaTeX document code. For a quick introduction to using LaTeX, see one of the resources linked below.

The output is extensively configurable, see ,help texconfig for more information about the possible configuration options.

LaTeX macros and packages may also be used in this command via inclusion into the preamble, see ,help preamble for more information.

If a guild or user has latex recognition enabled (see ,config latex and ,help autotex), messages containing LaTeX will automatically be compiled and this command is generally not required.

Aliases

​ ​ ​ ​ ​ ​ tex: Code is compiled in the default document environment.
, or mtex: Code is rendered in math mode, in a gather* environment.
​ ​ ​ ​ align: Code is rendered in math mode, aligned in an align* environment.
​ ​ ​ ​ texsp: Same as tex, but ||spoiler|| the output image.
​ ​ ​ ​ ​ texw: Don't pad the output (with transparent pixels) after compilation.
​ ​ ​ ​ ​ tikz: Code is rendered in a tikzpicture environment.

Related

​ ​ autotex: Toggle whether your LaTeX is automatically rendered.
​ preamble: View or modify your LaTeX preamble.
texconfig: View or modify your personal LaTeX rendering options.

Examples

,tex This is a fraction: \(\frac{1}{2}\)
,, \int^\infty_0 f(x)~dx
,align a + 1 &= 2\\ a &= 1
,tikz \draw(0,0) circle (1);

Have more questions?

Visit our support server here to speak to our friendly support team!

neat frost
#

Under LaTeX Resources are a few

#

Overleaf has many good ones

solid yarrow
velvet dagger
#

So I remembered it

#

Honestly? Numerical analysis I could see being interesting

#

Like idk much about it but

#

I'm guessing the idea is like, hey here's some shit you may wanna do

#

Solve some matrix equation or differential equation or whatever it may be

#

What are some methods to estimate shit? How quickly do they converge? etc

#

Probably not my cup of tea but I could appreciate it

#

I have analysis psets from a couple years before I took it and one problem they had is what I imagine numerical analysis to be on some level

#

Like that's kinda nifty. The coding part would probably make me wanna commit sudoku, healthy as it is

#

@sharp mulch maybe confirm I'm not talking too much shit?

#

Anyway my thing earlier was more just the fact that you didn't have to do algebra lol

sharp mulch
#

Huh what

velvet dagger
#

Just like, was that a total mischaracterization of numerical analysis lol

sharp mulch
#

A big part of numerical analysis is numerical linear algebra so solving Ax=b, factoring A=PLU/LL^T/QR/USV^T, multiplying C=AB effectively

#

Another big part is solving ODEs/PDEs

#

And you do want to have error bounds and convergence rates

velvet dagger
#

Gotcha

lavish hull
#

I never heard of PLU

#

Cholesky,QR and SVD I get

#

Not sure what PLU is

river moon
#

have you heard of LU decomposition

mint patio
#

The classic

lavish hull
#

Yes

#

what is the P matrix?

river moon
#

PLU or LUP is just LU with some Permutations

lavish hull
#

oh cool

#

if you dont mind what do you study?

river moon
#

optimization and machine learning hmmCat

lavish hull
#

cool stuff id say

#

i took a computational stats class

#

all my exposure to numerical linear algebra was in one class

#

i enjoy the topics

#

im assuming ur in academia

#

so what specifically do you study

river moon
lavish hull
#

o cooler then

#

industry is cool

neat lintel
#

Hmmm

#

Is $\mathfrak L$ better or $\mathcal L$ better for Laplace transforms?

fathom swallowBOT
#

brotherImusttalk1234

mint patio
#

The latter

#

Please

neat lintel
#

$\mathscr L$

fathom swallowBOT
#

brotherImusttalk1234

neat lintel
#

Huh

ripe dirge
#

L moment

river moon
#

use \mathfrak if you want to have a book that feels like it has been written in 1950ssmugCatto

alpine kindle
#

$\mathcal L$

fathom swallowBOT
#

ally ❤ (semaluhtounuyulohowwah)

echo tundra
#

$\mathfrak L$

fathom swallowBOT
#

numbpy (anti-glomed)

midnight kayak
#

$L$

fathom swallowBOT
#

MochaOhwelp

fervent seal
#

hi

eternal glen
#

I once attended a talk on Lie algebras where they referred to mathfrak as the "spooky vampire font" and honestly valid

little vine
#

$\mathfrak{I've come to suck your blood}$

fathom swallowBOT
#

cali5nia

little vine
#

Checks out

solid yarrow
#

weird flex?

eternal glen
#

is that seriously what $\mathfrak{y}$ looks like ew

fathom swallowBOT
#

dirichlettt

eternal glen
#

I was wondering why there was a random eta in there xddd

neat lintel
#

eta on

#

drugs?

cyan goblet
#

$\mathfrak{S}, \mathfrak{G}$

fathom swallowBOT
#

anamono for anamono 🍓

vocal vessel
zealous garden
#

,, \mathfrak{Transylvania} \subset \mathfrak{Romania}

fathom swallowBOT
#

wraithlord_kobordism

zealous garden
#

That's so not a T

#

That's an I

cyan goblet
#

$\mathfrak{J} \mathfrak{I}$

fathom swallowBOT
#

anamono for anamono 🍓

eternal glen
#

Professors using p and rho as variables except so much worse

trim vessel
#

yo dm me if you can help me with something that involves joining a server a using the search bar to find something

jovial ember
#

Chmonkey

neat lintel
#

Yo is Khan Academy and a few past papers enough for an AP Exam

solid snow
#

Most likely not

rain plinth
#

1-905-442-4151

wet berry
neat lintel
solid snow
#

some book

#

james stewart or ron larson's "Calculus" books

neat lintel
solid snow
#

yes

languid marten
#

Okay , So Linear transformations are a type of vector valued functions that maps V to U such that L(x+y) = L(x) + L(y) and L(ax) = aL(x) where x , y ∈ V and U respectively and a ∈ F(X,+,×) have I understood this correctly or Am I missing something ?

mental stratus
#

what are F and X

sturdy kindle
#

Same message in 3 different channels on the same minite

languid marten
mental stratus
#

and X?

languid marten
mental stratus
#

so what is the relation between X, and U,V

#

Because you can't leave that unspecified

languid marten
mental stratus
#

That makes no sense, a linear mapping is only defined between vector spaces that are over the same field

languid marten
mental stratus
#

So if F is your field then your v.s. U and V have to be over the field F and a linear mapping from U to V is any mapping that preserves the alg str.

languid marten
#

yeah sorry I forgot to mention that

bronze pelican
#

Chair monkey!

fair mural
#

looks like some weird character from gumball

languid marten
solar hawk
#

what does over mean

#

like a vector space is over a field means it gets it scalars from that field

#

what does a field over a set mean

languid marten
solar hawk
#

so X is F?

languid marten
#

F is a algebraic structure equipped with two binary operations and it's elements belong to the set X

solar hawk
#

okay

#

a field is a set itself though

mental stratus
#

the definition doesn't care about that but a lot of the theory developed in linear algebra is over fields with characteristic zero, and these are infinite. the mapping N^{X} to the field F defined k |--> k.1 is injective, indeed if for m, n in N^{X} if m.1 = n.1 then (m-n).1 = 0 and by the fact that a field does not have divisors of 0, m-n=0 which means m and n are the same therefore proving the injectivity of the said mapping

solar hawk
#

pika where did you learn linear

#

from a book?

mental stratus
#

N^{X} is just naturals without 0

#

Haven't finished learning it entirely lol, mostly axler, and morton curtis and a bit of this bit of that, did some abstract algebra from hungerford to make myself with some of that terminology, helps out a lot when you get to linalg knowing some group thelry and basic facts about fields like the fields of characteristic zero being infinite

#

Also cosets

mental stratus
#

Nope.

solar hawk
#

ik what groups,rings, and fields are but idk anything further

rugged blade
#

trying to understand the mathematics behind general relativity a bit better. I know it's a long shot, but does anyone have any useful recommendations on books about Rieminnian geometry/differential geometry?

blazing pawn
#

Have you seen any differential topoology before

#

What is your background going in

velvet dagger
#

I think people like Wald? It seems like it discusses a good bit of math

#

But yeah your background is pretty relevant

fallow pawn
#

bye they didnt even help me i literally cheated my way to finish

umbral forge
#

is there a general number of classes a math major should take per semester in uni?

forest vale
umbral forge
#

thats fair

#

i can send the list of what i have to take if that helps

#

im ofc talking with an advisor but rn its by mails so its rly slow

forest vale
#

i think your advisor would give better opinion than me lol

umbral forge
#

thats fair

forest vale
#

so, even if it's slow, it worth asking

umbral forge
#

basically im gonna be taking at least algebra 1 and analysis 1

forest vale
#

sounds good

#

because the stuff in year 1 is generally easier, i took around 4 classes only in my last year

umbral forge
#

but yeah im in quebec so its different, i basically start as a U1 student

forest vale
umbral forge
#

For the classes I’m taking next semester you mean?

forest vale
umbral forge
#

Thats a good plan yeah

#

I haven’t chosen everything yet cause I’m waiting on something but I can do that for the 2 I’ll be taking at least

forest vale
#

then you can try reading those stuff online and see if you can get used to them

umbral forge
#

Yeah I’ll try that

forest vale
#

i didnt prepare well enough for my analysis class in my first year, i failed it...

umbral forge
#

Is it because of difficulty or the different approach to math

umbral forge
#

That it’s like challenging

#

Yeah I heard everything is proof based

#

Well, a lot at lest

forest vale
#

I was so not used to the thinking process of it back then

umbral forge
#

Is it the same for algebra 1

#

I mean it does say methods of proof so I imagine so

#

Im just not sure the pace that’s expected to do everything

#

Anyway I’ll think it over and just wait for more answers from advisor thx

forest vale
forest vale
umbral forge
# forest vale I'm not sure if it is abstract algebra

Mathematics & Statistics (Sci): Sets, functions and relations. Methods of proof. Complex numbers. Divisibility theory for integers and modular arithmetic. Divisibility theory for polynomials. Rings, ideals and quotient rings. Fields and construction of fields from polynomial rings. Groups, subgroups and cosets; group actions on sets.

#

That’s the info given on the class

#

So yes I think

forest vale
#

ah

umbral forge
#

I should probably take a good look at my linear algebra notes from half a year ago before I start this

forest vale
#

tbh it really depends on the lecturer/prof

#

but it's fun if you understand those!

umbral forge
#

Not sure what’s meant by divisibility theory

#

I already had a class that went into methods of proofs and complex numbers tho

forest vale
#

for that, you don't really have to learn in advance

#

I'd trust lecturer/prof's design of studying pace

#

(although some don't really care XD)

umbral forge
#

I just hope I get lucky

#

It’s for an honours class so it should be fine

#

Oh also last thing before I go

forest vale
#

yea?

umbral forge
#

I have 4 classes of algebra and analysis in total required

#

Is it better to do them like in a row

forest vale
#

hmmm

umbral forge
#

Aka not skipping a semester of one of those

forest vale
#

yea

#

i bet you'll have some guidance when your in the welcoming week of the department

#

senior students might help planning

#

(that's what i get, I'm not sure if you have the welcoming week though)

umbral forge
#

Pretty sure I do

forest vale
umbral forge
#

But yeah ill ask a lot of questions cause so many classes are required and the order is a bit not clear even with the prerequisites written out

forest vale
#

don't be too shy to ask, and you'll be fine

forest vale
#

you can construct one in case you dont have it when it's time to apply for classes

#

it's a good logic practice

umbral forge
#

Mindmap is like a tree I imagine?

forest vale
umbral forge
#

Yeah probably should do that

#

It will give me something to do

#

Alright see ya 👋 and thx

forest vale
#

cya!

bronze sun
#

Guys, please me help with this VSCode problem. I don't know what to do.

ashen pike
bronze sun
#

I know.

#

Just asking in case anyone knows how to fix it.

ashen pike
#

Well this isn't a help server, so don't expect anyone to know. Just ask on a discord server thats designed for programming, or better, VScode

bronze sun
#

Okay, fair enough.

pulsar pagoda
#

the problem is using vscode at all

#

tbh

#

just use vim

#

and dont use language servers

stuck meadow
midnight kayak
stuck meadow
#

just, vsc code nice, but insome specific situations its not the best editor

neat lintel
neat lintel
#

ok

#

yeah

#

but what is the real and imaginary axis really

inland raft
#

Yes

velvet dagger
#

The real axis is the x axis, imaginary is y axis. If you're thinking about complex numbers

neat lintel
#

like what if you alrdy plot the equation on its real x and y coordinates and now u need a imaginary axis idk

#

ok ig im just over complicating it for myself

#

(x^2+1)(x+1) =0

#

this has a real solution AND an imaginary solution right

#

yess

#

now

#

suppose you plot the rest of the equation too

#

yeah

#

where would u plot that

#

in the z axis?

#

but then what happens to x = -1 when y = 0

#

y is 0 in that example

#

equation is (x^2+1)(x+1) = y

#

ok

#

i dont have to but i still do🥲

#

fair enough

solid yarrow
#

what's the most interesting conjecture you know of?

digital furnace
woven whale
solid yarrow
woven whale
neat lintel
#

Pre-uni student here, can anyone explain me to me how complex numbers can exist in real life, want to know out of pure curiosity

vast surge
neat lintel
#

Seems so hard to conceptualize imaginary numbers existing

vast surge
umbral forge
#

I think they’re used when working with electricity too

#

Im not sure if they’re needed for it or it’s just more useful to have them as a tool

hallow blade
#

If you accept that multiplication correpsonds to reflection, then you should also accept that complex numbers corresponds to defining a number system on the plane

steady sparrow
#

can someone help me with this question. Expand and state your answer as a polynomial in standard form.(4x-y^(3))y^(2)

lavish hull
steady sparrow
#

nope

lavish hull
neat lintel
neat lintel
umbral forge
#

Not sure if this helps

hallow blade
#

But why should multiplication by a negative be repeated substraction?

#

It's just arbitrary no?

#

in the same way, you can define a certain number system on the plane

#

which extends the number system defined on the line

neat lintel
hallow blade
#

for example, what if you just forgot about complex numbers

#

and just thought about defining a number system on the plane

#

What then does multiplication represent?

neat lintel
hallow blade
#

by number system i mean a field

#

i.e. one where you can do addition, multiplication, substraction, division

neat lintel
hallow blade
#

i mean my point is this: it's actually somewhat arbitrary that someone decided multiplication by a negative number means repeated subtraction

#

you first define multiplication for positive numbers and say it means repeated addition...fine

neat lintel
hallow blade
#

yeah

#

now let's say you want to extend to a number system on the plane

#

if you represent everything using rectangular coordinates, it's not actually so clear what's going on.

#

Let's say you have rectangular coordinates and you want to define (a,b) x (c,d)

#

What is the geometric interpretation of (a,b)x(c,d) being defined to be equal to (ac,bd)?

#

and also, does it make it into a number system/field if you define it like this?

#

Because remember, you also want to define (a,b)+(c,d) = (a+c,b+d)

#

Which implies that the additive identity is (0,0) which means that anything else you should be able to divide by

#

But then... how do you divide by (1,0)?

#

so you immediately see that you can't define it like this if you want a number system

mental stratus
#

(1,0)*(0,1)=0 so zero has divisors therefore not a field

hallow blade
#

Of course now it's not at all obvious how to define multiplication. But interestingly, if you switch to polar coordinates, stuff becomes perhaps more clear

#

If you now think about how to define multiplication on (r_1,theta_1)x (r_2,theta_2)

#

you end up with (r_1r_2,theta_1+theta_2)

neat lintel
hallow blade
#

well okay just forget about that point its not so important, the bigger point is that you cannot define a number system

neat lintel
hallow blade
#

Which translates to polar as (1,0)x(1,pi) = (1,pi)

neat lintel
hallow blade
#

read what I replied to it

hallow blade
#

The example I gave being multiplication by negative number

neat lintel
lavish hull
#

maybe not physical, but existing in reality

#

actually i can agree because a lot of concepts are too hard to make analogies with reality

neat lintel
#

at what point did we say, okay hold on, just because it doesn't have a physical interpretation it can still exist, was it when we started seeing complex numbers in real life equations or did this idea exist prior to it

hallow blade
#

not sure about the history of it all

lavish hull
#

maybe before math was invented @neat lintel

hallow blade
#

According to veritasium's video, complex numbers were introduced as a computational aid when solving polynomial equations

lavish hull
#

language gets pretty abstract too

neat lintel
hallow blade
#

i mean what is the physical interpretation of the quadratic equation?

lavish hull
#

trajectories

neat lintel
hallow blade
neat lintel
hallow blade
#

though Im not familiar with how projectile motion is derived without calculus

lavish hull
#

even more generally polynomial equations can be representitive of a lot of things

hallow blade
#

There is this guy on youtube that you might find interesting @neat lintel nj wildberger or something

neat lintel
hallow blade
#

no he is a guy that likes to talk about how modern mathematics is wrong

neat lintel
lavish hull
#

no he is a professor

hallow blade
#

because the objects we use, namely real numbers, do not exist

neat lintel
tiny forge
#

nj wildberger has very "non standard" views on things from what i remember

hallow blade
tiny forge
#

hes a finitist iirc

neat lintel
hallow blade
#

for context,you probably want to first understand what a real number actually is

tiny forge
#

people who do not accept the existence of infinite objects

hallow blade
#

though im not sure if its strictly necessary to understand his viewpoint

#

yes he is very very outside of mainstream mathematics in that he is literally trying to make a new mathematics on his own

hallow blade
#

but the idea that real numbers actually don't exist, nonetheless are very convenient is quite interesting

lavish hull
#

and every mathematician wants to make new math

hallow blade
neat lintel
hallow blade
#

he has content where he builds math up "rigorously" using his viewpoints

#

and he even sells it iirc

tiny forge
#

But the people who do think about these kinds of things generally accept them as existing yes

#

Otherwise things are very difficult

neat lintel
#

.

woven whale
#

kids these days

jovial ember
#

Chmonkey

quiet geode
#

oi mods

#

my ass is patiently waiting for 'very active' role

echo tundra
#

very active role is not controlled by the mods

quiet geode
#

thats what they said to me last time around as well

#

truly believe its an escape hatch sleep

neat lintel
quiet geode
#

i am very actively promoting this server irl

echo tundra
#

That doesn't count sadly

quiet geode
#

nice discussion

#

YOOO

#

WE HAVE @strange meteor

#

are we going to war

neat lintel
# tiny forge But the people who do think about these kinds of things generally accept them as...

I thought/assumed that the things we talk about in formal systems are confined to just the formal system. The interpretation of the formal system I assume can then be used to see if a different formal system can be interpreted in the same model?
And if you want to capture some idea it needs to be written in formal language, and all that captures is just the formal definition according to the formal system.
And natural language I assume doesn't have an exact mapping to formal language, so you don't know whether the idea expressed in natural language matches your formal definition or not.
I assume physics then is a bunch of models that are gathered by thinking about replicable measurements of what we perceive to be the external world, and then expressing these replicable properties in formal language? And then using what we know about formal language to talk about them?

quiet geode
#

apparently i am not allowed to upload images 😢

neat lintel
quiet geode
#

i can do that but i want the mods to acknowledge my helpfulness and promote me to a greater being as well hmmCat

#

here you go

neat lintel
quiet geode
#

the natural medium

neat lintel
quiet geode
#

there is no natural medium outside of the formal language

#

it is as natural as it gets

neat lintel
quiet geode
#

my subscription for a working brain ends here, i cant help you anymore

#

back to my troller self

neat lintel
#

Learn more about the Bystander Effect: https://practicalpie.com/the-bystander-effect-definition-examples/
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▶ Play video
neat lintel
quiet geode
#

i feel attacked

#

Also

neat lintel
#

Losing my mind

#

tried 100 different names for my 2nd account

#

all taken

fair mural
#

random numbers go

neat lintel
#

652336711325712386

ocean harbor
#

69

granite hound
#

Oh cool an Abstract Algebra study group starts up just when I started actively self teaching it 🙂

#

I should power through the last chapter of Understanding Analysis before it starts up

tawny iris
#

hey guys

solid yarrow
#

hello

granite hound
#

Hi

ocean harbor
#

ded

quiet geode
#

dead is good

olive basin
#

can any1 help me

quasi jettyBOT
neat lintel
#

Lol

#

Is that automatic

#

Help

#

Help me

#

Can anyone help me

#

Ok it’s not

#

!help

quasi jettyBOT
neat lintel
#

Hmm idk how it did that

#

Can any1 help me

#

weird

#

!help @neat lintel

quasi jettyBOT
neat lintel
#

yeah idk

magic owl
#

reading too hard

neat lintel
#

is capital pi notation useful or can it be expressed with summation

#

I don’t think it’s used all that much tbh but I’m wondering

storm sage
#

It works the same way as the capital sigma notation

#

So it's not like you have to learn anything special with it

neat lintel
#

They are the same?

fervent pebble
#

capital pi is multiplication and capital sigma is summation

#

i mean you can represent each in terms of the other (for real positive terms) but why would you want to

neat lintel
fervent pebble
#

ofc

neat lintel
#

g

fervent pebble
#

if you want to, for $x_k$ positive and real, see how you could turn $\prod_{k=0}^{\infty} x_k$ into $\sum_{k=0}^{\infty}y_k$, where each $y_k$ is real

neat lintel
#

\prod

fathom swallowBOT
#

valley

neat lintel
#

I don’t know how to otherwise I would try

fair mural
#

x = e^ln(x)

#

use that

neat lintel
#

I haven’t taken precalc so I haven’t used summation or natural log yet

#

Only practice problems with logarithm rules

#

no actual applications

fair mural
#

i mean, that’s literally all you need though

neat lintel
#

I don’t even know where I’d begin. My first thoughts were using a tower of exponents or putting another summation inside of the first

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idk how to do anything with e^ln(x) it means nothing to me

neat lintel
small dust
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y_0 = \prod x_k, y_n = 0 for n > 0

neat lintel
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lol

solid snow
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Could you elaborate

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Oops

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Chat didnt scroll down lmao

fervent pebble
neat lintel
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i want to know what final expression you have in mind

fervent pebble
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ohh

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||ln(prod) = sum(ln)||

neat lintel
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of course

fervent pebble
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is there a different way to do it thinkies

neat lintel
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maybe i just misunderstood what you originally meant by "turn into"

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i read it as "make the product literally equal to the sum"

fervent pebble
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ohhhhhh

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x_k = y_k = 0 hehe

neat lintel
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yeah alright this is fine

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i just misunderstood you

fervent pebble
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in your defense "turn into" is definitely not a very mathematical term

fair mural
woven rapids
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bro there's a latex bot? that's so coollllll

fervent pebble
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stop 💀

lavish scaffold
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@cold needle please ban @wild comet this spammer from this server

echo tundra
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@cursive token can I DM you about the abstract algebra group?

cursive token
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Feel free