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/sci/ - Science & Math


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12265984 No.12265984 [Reply] [Original] [archived.moe]

Formerly >>12251002

>tfw low iq autist edition

>what is /sqt/ for
Questions regarding math and science, plus related advice requests outside of career advice.
>where should I go for career advice?
>>>/sci/scg
>/scg/ isn't up, hit me with the pasta
https://pastebin.com/jX5bLgQd
>where do I go for miscellaneous advice?
>>>/adv/
>where do I go for other SFW questions and requests?
>>>/wsr/ , >>>/g/sqt , >>>/diy/sqt , etc.
>books?
https://spoon.wiki/Books
https://stitz-zeager.com/
>articles?
sci-hub.st
>book recs?
https://sites.google.com/site/scienceandmathguide/
https://4chan-science.fandom.com/wiki//sci/_Wiki
http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>help with calculus?
https://spoon.wiki/WolframAlpha
>how do I post math symbols?
https://imgur.com/MDiglsS.png
>a google search didn't return anything, is there anything else I should try before asking the question here?
https://scholar.google.com/
>where do I look up if the question has already been asked on /sci/?
>>https://warosu.org/sci/
https://boards.fireden.net/sci/
>how do I optimize an image losslessly?
https://trimage.org/
https://pnggauntlet.com/

Question asking tips and tricks:
>attach an image
>if a question has two or three replies, people usually assume it's already been answered
>ask anonymously
>check the Latex with the Tex button on the posting box
>if someone replies to your question with a shitpost, ignore it

Stuff:
Meme charts:https://imgur.com/a/JY6NNeL
Serious charts: https://imgur.com/a/0qDEgYt (Post any that I've missed.)
Verbitsky: https://pastebin.com/SmBc26uh
Graphing: https://www.desmos.com/
Tables, properties, material selection:
https://www.engineeringtoolbox.com/
http://www.matweb.com/

>> No.12265993
File: 1.73 MB, 500x250, Complex_theta_animated1.gif [View same] [iqdb] [saucenao] [google] [report]
12265993

>>12265984
First for the Jacobi [math]\theta[/math] function.

>> No.12266017
File: 174 KB, 1446x2048, __cirno_touhou_drawn_by_kae_karee__5f7f15fb81a3c3e8406c84be2b4198f1.jpg [View same] [iqdb] [saucenao] [google] [report]
12266017

>>12265993
Based.

Unanswered questions:

Maths questions:
>>12253153
>>12256452
>>12256864
>>12259081
>>12260413
>>12261608

Physics questions:
>>12257237
>>12259360

Chemistry questions:
>>12261033

Engineering questions:
>>12256864

Biology questions:
>>12251981
>>12263455

Stupid questions:
>>12251006
>>12252258
>>12253832
>>12254466
>>12255820
>>12256752
>>12257520
>>12261773 [No.]
>>12265252 [Please.]

>> No.12266069

Hi, retard here. So I've been thinking but its not going so well.
I thought about space and the universe and stuff. And the universe is infinite right? And that means that there are infinite many things inside it too right?
But I also think I heard on numberphile or something when they talked about big numbers that some numbers are bigger then the number of atoms in the universe.
Someone please help me, where did I get it wrong?

>> No.12266072 [DELETED] 
File: 28 KB, 463x378, circuit6.png [View same] [iqdb] [saucenao] [google] [report]
12266072

I posted this in the last thread (and it's on the list of unanswered questions above), but just in case anybody knows I'll make a new post. Could it be some sort of programable current source? The value of R1 can be set to decide how much of the current sourced by the top mirror is sinked in the botton mirror and how much goes to RL. Does that make sense? Any other suggestion is welcomed.

>> No.12266076
File: 28 KB, 463x378, circuit6.png [View same] [iqdb] [saucenao] [google] [report]
12266076

I posted this in the last thread (and it's on the list of unanswered questions above), but just in case anybody knows I'll make a new post. I'm trying to figure out what this circuit does. I know it's a common emitter with an active bias and active load, but I'm not sure what it could be used for. Could it be some sort of programable current source? The value of R1 can be set to decide how much of the current sourced by the top mirror is sinked in the botton mirror and how much goes to RL. Does that make sense? Any other suggestion is welcomed.

>> No.12266103

>>12266069
No one knows for sure if the universe is finite or infinite. What they were probably talking about is the observable universe, everything close enough that light from it can reach us in less time than the age of the universe.

>> No.12266121

>>12266103
That makes sense with the observable universe and the number of atoms part.
But the universe not being infinite part. Granted im a physicslet or whatever discipline the size of the universe question falls in. But all my life I've heard that the universe was infinite and that there was inifinte many versions of me doing infinite many different things right now. Is that just speculations?

>> No.12266139

>>12266121
The Everett multiverse being infinite is pretty solid theory imo but still debated, the actual universe being infinite is shakier afaik, either of those being true would be enough for there to be infinite copies of you, so it's very plausible but still not completely settled.

>> No.12266166

>>12266139
Ok so I got it mixed up. Its not like there are some other me that I could theoretically travel to by a spaceship. That dude is in some other universe whatever that means.
I just read the multiverse wiki page fast and it says parallell universe so I assumed I cant travel there.
I dont know what I think about this. Maybe its better this way, not being able to travel to the other you by spaceship. Hope you cant travel to a parallell universe.

>> No.12266950

>>12266076
idk, but if you simulate it you find it has unity gain when R2>=R1, otherwise it has zero gain. Also, if you study differential pair amplifiers, you'll hear that while an emitter resistor to control current is passable, a proper current sink is better for large swing and linearity.
Looks like the output stage of an opamp.

>> No.12267033
File: 45 KB, 1327x768, Screenshot_20201024_041656.png [View same] [iqdb] [saucenao] [google] [report]
12267033

>>12261033
IUPAC Blue Book, section A-2
https://www.acdlabs.com/iupac/nomenclature/79/r79_36.htm

>> No.12267043

First year geology student here (Europe). What can I expect career-wise?

>> No.12267045

>>12267033
and section A3, A4 goes over unsaturated chains

>> No.12267110

When charging an electric car, are the batteries charged in series or parallel?
Would 1000 parallel busses fast-charging each cell be able to "refill your tank" in less than 5min?

>> No.12267201

I throw 2 coins at the same time several times in a row.
Each time both of them show either tails or heads at the same time, so we get pairs like (H, H), (T, T), (T, T)...
Is the correlation coefficient 1?

In theory, we can assume that two coins represent independent random variables. So their correlation is 0?

>> No.12267340

>>12267110
> When charging an electric car, are the batteries charged in series or parallel?
A combination of the two. I.e. you have series-connected chains of cells, several of which are connected in parallel.
> Would 1000 parallel busses fast-charging each cell be able to "refill your tank" in less than 5min?
Not if you want the cells to last more than a few charge cycles. The primary limiting factor is the speed at which you can charge an individual cell without damaging it.

>> No.12267414

>>12267201
Thevmeasured correlation is 0,the theoretical correlation is 1 . It's a very unlikely result though, the probability of it halves each time you flip.

>> No.12267423

>>12267414
>The measured correlation is 0,the theoretical correlation is 1 .
Wait a minute! Strike that. Reverse it. Thank you.

>> No.12267717

Where can I find how to solve the non homogenous legendre differential equation?

[math]\frac{d}{dx}\left( (1-x^2)y'\right)+\left( l(l+1)-\frac{m^2}{1-x^2} \right)y[/math]

They all solve it for m=0 and then they don't say anything more. Maybe I'm missing something

>> No.12267779

best software/web app for fast sketching math equations? not a solver, more like a notebook substitute

>> No.12267780

could you add a convergent sequence and a non-convergent sequence to make a convergent sequence.

i thought of two non convergent sequences added together to make a convergent one but i can't think of this one

>> No.12267814

>>12267780
No.

>> No.12267832

>>12267201
the pair of coins represent a single random variable with two outcomes. Define
[math](H,H)=1[/math]
[math](T,T)=0[/math]
the sequence is presumably a Bernoulli process with [math]p=0.5[/math], in which realizations are independent.
[math]Cov[X_n,X_k]=E[X_nX_k] - E[X_n]E[X_k] = E[X_n]E[X_k](1-1) = 0[/math]

>> No.12267879 [DELETED] 

>>12267780
if you add [math]cos(\pi n)[/math] and [math]-cos(\pi n)[/math] you get a trivial convergent sequence.

>> No.12267896

>>12267780
Let [math]y_n[/math] diverge and [math]x_n[/math] converge
[math]lim(y_n)=lim(y_n+x_n-x_n)=lim(y_n+x_n)-lim(x_n)[/math]
so the sum diverges

>> No.12267909

>>12267896
excellent thanks

>> No.12268154

I've been studying math for a good week straight and the instant someone posts something remotely I start getting horny and it affects my productivity. How do you bros handle it? I want to get an A this semester.

>> No.12268158

When has repeated lockdowns ever worked?

>> No.12268296
File: 1.83 MB, 2785x1540, __konpaku_youmu_and_konpaku_youmu_touhou_drawn_by_pegashi__9d8fe311f6b4ce7ca8039defcafa24dc.jpg [View same] [iqdb] [saucenao] [google] [report]
12268296

I've added https://spoon.wiki/WolframAlpha to the pasta a couple threads ago and no one spontaneously commented anything, so I'm explicitly asking you guys to tell me if the """tutorial""" looks good (you can also just edit it into something better, obviously).
>>12268154
>something remotely
Remotely what?

>> No.12268305

>>12268296
>Remotely what?
Lewd
I think my brain shortcircuited

>> No.12268366
File: 113 KB, 559x694, electric field.png [View same] [iqdb] [saucenao] [google] [report]
12268366

Why does the formula for the electric field not include the test charge (big Q)? The paragraph in the middle says that it makes no reference to it and then stops there. Is it because it is just a "test charge" that we placed somewhere so it shouldn't have any actual effect on the field strength?

>> No.12268474

If an object traveling 20 m/s is struck causing a sudden reversal of direction with the object now traveling 30 m/s in the opposite direction, would the 20m/s be the initial velocity, -30 the final velocity, and the net work done be given by the formula: w = 0.5(mass)(finalVelocity^2 -initialVelocity^2)? Or am I completely wrong? Some hints would be nice at least.

>> No.12268496

>>12268366
The test charge exerts no force upon itself. If you were to add another charge, it would change the field at every point other than the point where you placed the charge.

>> No.12268497

>>12268474
assume we know the mass*

>> No.12268513

>>12268474
> If an object traveling 20 m/s is struck causing a sudden reversal of direction with the object now traveling 30 m/s in the opposite direction, would the 20m/s be the initial velocity, -30 the final velocity
Or vice versa; you could state that the initial velocity was -20 m/s and the final velocity 30 m/s. Which direction is positive is an arbitrary choice.

> and the net work done be given by the formula: w = 0.5(mass)(finalVelocity^2 -initialVelocity^2)? Or am I completely wrong?
That is the work done on the mass which changed direction. The net work is zero (conservation of energy); whatever imposed the force would lose an equal amount of energy to that gained by the mass.

>> No.12268540

>>12268474
if you're talking about work done to the object, then you're correct
work-energy theorem

>> No.12268577

>>12268366
because electric field can be thought of as "electric force per unit charge"

>> No.12268599

>>12268513
>>12268540
Thank you very much, I really appreciate it.

>> No.12268705

If you run in a "constant" rainfall, would the total amount of rain on your clothes be more or less than if you were to just "walk" normally?

>> No.12268714

Why do plastics convert to estrogen or leach estrogen like chemicals? Polyethylene is a simple hydrocarbon, looks nothing like the aromatic groups of a hormone. Or is it only more complex plastics that are dangerous? And if so, is pure polyethylene in practice safe, or is it generally mixed with other less safe plastics or chemicals?

>> No.12268774

>>12265984
For engineers. How did everybody did in their first year of engineering? I am in my first year and it sucks ass for me.

>> No.12268791
File: 6 KB, 254x161, line integrals.png [View same] [iqdb] [saucenao] [google] [report]
12268791

So this question popped up and I just want to see if my "understanding" is correct. If the line integral of C1 is 0 then C3 + C4 = 0 and C2 would also be 0 because of the Path Independence thing, right? Apparently, C2 gives a number that isn't 0 which has me pretty confused.

>> No.12268794

>>12268774
high all day drunk all night

>> No.12268796

>>12268774
Pretty bad for me because of the corona and the professors are real bad with heavy accents and obvious disinterest.

>> No.12268831

>>12268796
>Pretty bad for me because of the corona and the professors are real bad with heavy accents and obvious disinterest.
Are you me? Several of my teachers are hard to listen because their accents, combined with online classes it made it impossible to learn anything. Especially a pajeet that I have for the engineering problem solving class. I want to kms.

>> No.12268866
File: 657 KB, 2563x3288, 24128c0c4b63e1791b128c8877400788.jpg [View same] [iqdb] [saucenao] [google] [report]
12268866

>>12268791
If you know the field is conservative, then yes C1=C2=C3+C4=0
>>12268774
it only got worse
>>12268714
coca cola bottling company wants you to have cheap HRT
>>12268705
you should move as quickly as possible, unless you have a tail wind in which case you should match the horizontal component of the speed of the rain drops
http://snowball.millersville.edu/~adecaria/DERIVATIONS/Rain.pdf

>> No.12268878

>>12268866
>you should move as quickly as possible, unless you have a tail wind in which case you should match the horizontal component of the speed of the rain drops
Thank you for satiating my curiosity, this question has been nagging me for almost a year. I'll run when I don't have an umbrella then.
I hate that sci doesn't have spoilers but can you at least tell me if the picture is a guy or not...

>> No.12268952

>>12268866
I know you are a furfag so you could probably gave me an explanation about your hobby/fetish. I will like to gain insight in the psyche of furfags as part of my research. I am quite curious about the following
>What is the appeal?
>Why so many furfags are so degenerate?
>I read that at least 45% of this group identify as bisexual, is that true?
>Are you fag? Is so why?

>> No.12268971
File: 131 KB, 585x800, 9665c87485483ae1d6284f8fb47fa993.jpg [View same] [iqdb] [saucenao] [google] [report]
12268971

>>12268952
"Lurk moar."

>> No.12268985

>>12268971
That doesn't answer my question.

>> No.12269012

>>12268866
>field is conservative
Jesus I can't believe I forgot about this, thanks king.

>> No.12269031
File: 81 KB, 1089x303, circulation.png [View same] [iqdb] [saucenao] [google] [report]
12269031

For circulation, could we also use the integral symbol with the circle thing inside of it? Since A = B so it would be a loop wouldn't it?

>> No.12269032

>>12268952
Not him.
>What is the appeal?
The way they draw and represent animals. At least for me.
>Why so many furfags are so degenerate?
Furries are one of the most tolerant communities. It doesn't matter how disgusting or degenerate is your fetish you will welcome within the furry fandom.Therefore that gives them free rein.
>I read that at least 45% of this group identify as bisexual, is that true?
I read that survey as well and is probably true. Sexuality in furry fandom is too diverse. Most of new furfags that enter are attracted to anthro female characters, but they slowly get turn into bisexuals or fags later due to prolonged exposure to the fandom.
>Are you fag? Is so why?
Bisexual. Started with female characters and the more time I passed in the fandom I develop a liking for male characters.

>> No.12269038

>>12269031
if it is a closed loop, yes

>> No.12269194

>>12269032
this is extremely unsettling

>> No.12269349

>>12269032
This is extremely based.

>> No.12269359

Pasta update because the /scg/ pasta is now being hosted somewhere else:

>what is /sqt/ for
Questions regarding math and science, plus related advice requests outside of career advice.
>where should I go for career advice?
>>>/sci/scg
>/scg/ isn't up, hit me with the pasta
https://sciencecareergeneral.neocities.org/
>where do I go for miscellaneous advice?
>>>/adv/
>where do I go for other SFW questions and requests?
>>>/wsr/ , >>>/g/sqt , >>>/diy/sqt , etc.
>books?
https://spoon.wiki/Books
https://stitz-zeager.com/
>articles?
sci-hub.st
>book recs?
https://sites.google.com/site/scienceandmathguide/
https://4chan-science.fandom.com/wiki//sci/_Wiki
http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>help with calculus?
https://spoon.wiki/WolframAlpha
>how do I post math symbols?
https://imgur.com/MDiglsS.png
>a google search didn't return anything, is there anything else I should try before asking the question here?
https://scholar.google.com/
>where do I look up if the question has already been asked on /sci/?
>>https://warosu.org/sci/
https://boards.fireden.net/sci/
>how do I optimize an image losslessly?
https://trimage.org/
https://pnggauntlet.com/

Question asking tips and tricks:
>attach an image
>if a question has two or three replies, people usually assume it's already been answered
>ask anonymously
>check the Latex with the Tex button on the posting box
>if someone replies to your question with a shitpost, ignore it

Stuff:
Meme charts:https://imgur.com/a/JY6NNeL
Serious charts: https://imgur.com/a/0qDEgYt (Post any that I've missed.)
Verbitsky: https://pastebin.com/SmBc26uh
Graphing: https://www.desmos.com/
Tables, properties, material selection:
https://www.engineeringtoolbox.com/
http://www.matweb.com/

I don't think I've ever actually explained to you guys why do I do this.
The answer is, basically, that I make the threads from my phone, since my PC's IP range is banned from making threads, and modifying the pasta in my phone sucks.

>> No.12269390

Please respond.

>>12257237

>> No.12269477
File: 243 KB, 501x354, 1585786656788.png [View same] [iqdb] [saucenao] [google] [report]
12269477

How do I force myself to fall asleep?
Normally I have absolutely no problem falling asleep, but the moment something important happens the next day I end up laying there in my bet conscious the entire fucking night and I just want to run into a wall and knock myself out but I can't because I wouldn't land on my mattress.

>> No.12269484

>>12269390
bro nobody knows how to even visit your shit link
also what are we supposed to comment?

>> No.12269578

>>12269484
You access it at lainchan dot org/lambda/ res/9558.html#19751

>> No.12269589

>>12269390
I check the pdf and I don't really know what are you really trying to express anon. Give me a quick rundown.

>> No.12269642
File: 52 KB, 455x627, 2018-01-24 01_55_19.jpg [View same] [iqdb] [saucenao] [google] [report]
12269642

>2*3*5*7*11*13*17*19 = 9,699,690
What did G_d mean by this?

>> No.12269670

>>12269477
Tie the mattress to your back first, then run at the wall and knock yourself out. You'll fall backwards onto the mattress.

>> No.12269718
File: 26 KB, 211x220, 1598297119505.jpg [View same] [iqdb] [saucenao] [google] [report]
12269718

>>12269484
I'd like to learn if my research is noteworthy and anything extra is a plus.
>>12269589
QRD
>it's a cellular automaton
>that takes a 2D grid
>and through anisotropy evolves it into a final state of 1D arrays:
111
000
111
>these arrays are evolving in succession due to cellular automaton cell search algorithm
>so the algorithm is three-fold
>first it does a neighborhood count, which is regular cellular automaton behavior
>then it manipulates its environment
>then based on this manipulated environment, it manipulates itself back again
>the cell becomes a 0-1 binary switch
>this is ferrimagnetism
>the anisotropy is ferromagnetism
>the 1-0-1 layers are antiferromagnetism
>the model is indeed showing critical values at the Ising model
>it's actually acting like a soap bubble between two rings too
>wait so soap bubbles can be used to solve Ising systems?
>yes, because both try to minimize the systems energy and reach a ground state https://arxiv.org/pdf/cs/0406056.pdf
>turns out they can be used both to attack P?=NP
>the cellular automaton is giving critical values at exact trigonometric definitions
>it's actually solving an equation
>a
>cellular
>automaton
>solving
>equations
>I actually worked out that the exact equation (not included)
>phase transitions are actually algorithmic and mathematically expressible

the model is surfing on the 0-1 quantum sphere in the pic related.

Does it make sense?

>> No.12269817
File: 14 KB, 198x220, homogeneous_equations.png [View same] [iqdb] [saucenao] [google] [report]
12269817

>>12265984
PLEASE HELP ME FAST.

Which of the equations in the image are homogenous? I really need the answer in less than an hour and a half. Thanks.

sen=sin btw.

>> No.12269826

>>12269817
I have a timer set for an hour and forty five minutes to give you the answer.

>> No.12269829

>>12269826
Please help me fren, I beg you...

>> No.12269908

>>12269817
A differential equation is homogenous if it can expressed in the form [math]y' = \frac{f(x,y)}{g(x,y)}[/math], where [math]\deg(f) = \deg(g)[/math].

>> No.12270003

>>12265984
why are people so autistic about tokiko? I mean barely any other PC98 characters receive as much attention

>> No.12270030
File: 883 KB, 800x800, 1586981095332.jpg [View same] [iqdb] [saucenao] [google] [report]
12270030

>>12269718
This seems really interesting. You told me that this automaton can solve equations. Can you give me an example? It works with any kind of equation? What are the limitations of this automaton? Is turing complete? How could you implement this in IRL?

>> No.12270031
File: 165 KB, 850x1202, 30160b11617bb3d0c68187666cf7e8b4e.jpg [View same] [iqdb] [saucenao] [google] [report]
12270031

Is anyone here really high or used to dealing with schizos?
>>>/wsr/910572 needs your help. You just need to know basic calculus.

>> No.12270039

>>12270031
What the hell is he doing?

>> No.12270047

>>12270039
I have no idea.
He seems to have deleted some of his posts, but the conclusion he reached is retarded, so he still needs help.

>> No.12270364

>>12269817
Only I and II are homogeneous.

>>12269908
That's a sufficient condition, but not a necessary one. In this case, it excludes the first example. A more general definition is that you can rewrite f(x,y) as g(y/x), which is true if (not "only if") f(x) is the ratio of homogeneous polynomials of the same degree.

The reason why homogeneity is useful for ODEs is that substituting y=u*x results in the RHS being a function of u alone (x's cancel) and you're left with (1/x)dx=g(u)du. In the case of I, cos(π+y/x) becomes cos(π+u).

>> No.12270710
File: 273 KB, 1200x720, nn quine.jpg [View same] [iqdb] [saucenao] [google] [report]
12270710

>>12270030
Well you gotta first undertand that this is not any automaton but a cellular automaton. A cellular automaton is a system of whose is highly dependent on its neighbors because of the CA rules. What I have slid in the code is the cell manipulating its environment, before the CA code is being run. This is unheard of, and kind of similar to a system creating a constraint / axiom which then builds the system. I have not investigated the Turing completeness of it, but since it runs on a Turing strip, what the above setup does is using a Turing strip (not the memory strip) as the memory. One Turing strip overwrites the other Turing strip, which in turn changes the first Turing strip back. Pretty crazy huh?

People in the know of cellular automata business would tell that they are used to model complex problems like Navier-Stokes already. This is not solving, it's modeling the solution for insight.

For instance, take pic related as an example. It's a Neural Network Quine, a very interesting research about a NN replicating itself and publishing it as an output. This output is currently undecipherable, which is the deep learning blackbox.

This output is very similar to the initial random distribution input of my automaton. Since a neural network is in itself a correlated system (self-correcting weights), I can translate the neural network node to a magnetic state, whether it's corresponding to any of the magnetic states (ferro-ferri-antiferro-para-magnetic).

This is where I start applying the exact equation I've obtained for the 6-6 neigbor configuration I've shared in the presentation. I can change the configurations, relax or tighten the system. Tightening the configuration makes the system more conventional Ising, loosening is something I haven't considered thoroughly.

I then plug these results into the trigonometric - hyperbolic transformations I've established, The output is a cotangent graph.

>> No.12271087

Does anyone have a reliable place where i can find an SPSS torrent?

>> No.12271295

Is making it through university actually worth it?
I started university this year and I'm feeling like I'm learning stuff at 20% of the efficiency I could if I just quit and self learned everything. Not only that, at least 50% of the stuff is absolutely irrelevant and I will have without any doubt forgotten all of it by the time I graduate. It's also destroying my passion for the subject.
Should I drop out?

>> No.12271334

>>12271295
I have no idea how you can say all of that, IMO university was a lot more fun than actually working. If you just started, you probably have bullshit survey classes for now, but things will get better a few semesters in. The easy way out is to just half-ass your way through the shit you don't like and instead use the extra time to learn stuff you actually enjoy. If you actually think university is destroying your passion then you should talk to someone about it, maybe you have some professor/mentor/whatever.

>> No.12271353
File: 3.67 MB, 4032x3024, 20201018_150116.jpg [View same] [iqdb] [saucenao] [google] [report]
12271353

i literally have my bachelors in maths, and im tutoring a 15 year old. he sent me this question asking for help
i unironically have no idea how to solve it

>> No.12271355

>>12271353

Start with a new phone

>> No.12271376

>>12271353
Come on anon, this is not difficult.
1. write down equation relating X to 54 angle + unknown 1
2. write down equation relating X to 26 angle + unknown 2 (you do know how to do this, right?)
3. combining 1 and 2 you can get a relation between unknown 1 and unknown 2
4. use said relation to solve for X in either equation 1 or 2

>> No.12271380

>>12271376
yeah, but it asks for geometric reasoning
ive never done geometry in my life

>> No.12271385

>>12271380
you're a failure and should stop tutoring kids
it's beyond me how you got your bachelors

>> No.12271388
File: 500 KB, 1000x1320, 13788741c4c3da8688728f8ef68a7e688.jpg [View same] [iqdb] [saucenao] [google] [report]
12271388

>>12271353
[math]DE + EA = 2DBA = 2*(54 + X)[/math] and [math]DB + BA = 2DEA = 2*(26 + X)[/math]. Since [math]DE + EA + AB + BD = 360[/math], you have [math]360 = 2*54+ 2*26 + 4X[/math].

>> No.12271390

if i have a shit diet should i be taking multivitamins? seen a lot of people say theyre pretty much useless

>> No.12271400

>>12271380
Wait, sorry. I didn't realize it asked for a specific method. You can solve this by drawing some new lines. You need to do two things:
1. "drag" point E up to point F and extend the line ending at C so you get a new triangle with angles 54, (X + 26) and angle at A
2. in the same way "drag" point B up to C to get a similar angle X+54

Finally, solve for X.

>> No.12271518

I have to use the Gauss-Jordan method to find the inverse of the a b c d matrix to get the formula for the inverse, I did it on paper and it's simple enough but I am having a real hard time making it look somewhat not shit in LaTeX, is there any easy way to input Matrices with row operations into LaTeX? There's a lot of fractions and shit that ruins my formatting.

>> No.12271529

I'm not sure if this the right place to ask, but is it normal to feel like you don't retain much anymore due to information overload? I've been having that issue in my grad classes.

>> No.12271536

>>12271529
of course, it's called cramming
that's why universities suck, they force you to cram shit all the time

>> No.12271542

>>12271529
Completely fucking normal.
You need to have good memory or actively work on old material to remember them.

>> No.12271646

the heck happened to scg? thread got deleted while i was asleep

>> No.12271659

Question for those enrolled in US colleges. With this corona bullshit and online classes, is there an option instead of enrolling in a class, just prepare for one single exam on your own and then take the exam and if you pass it you pass the class?

>> No.12271660

>>12271646
Mysterious are the ways of janitorial staff.
They're probably particularly peeved because of the new ads.

>> No.12271682

>>12271659
no

>> No.12271685

>>12271660
niggers, the lot of them

>> No.12271696
File: 148 KB, 1011x1024, 1603380032442.jpg [View same] [iqdb] [saucenao] [google] [report]
12271696

So I was in Public wifi on /k/ and I posted a version of the Argentinians aren't white copypasta thst was heavily modified to make fun of Chinese communists. But as soon as I posted it my wifi signal went dead. Than I exited out of 4chan and my internet connection came back. Than I went back on 4chan and my signal cut out again. Rinse and repeat.
Was it a coincidence or was someone watching my posts and kicked me off when i posted the copypasta?

>> No.12271700

>>12271696
based retard poster

>> No.12271879
File: 3 KB, 178x130, Screenshot 2020-10-25 164145.jpg [View same] [iqdb] [saucenao] [google] [report]
12271879

if you have a matrix like pic related, does the rank equal 2 or 3 for x in reals?

>> No.12272167

>>12271879
Rank 3 if x≠0, rank 2 if x=0.

>> No.12272178

>>12271879
It's contingent on the value of x.

>> No.12272183

>>12272167
>>12272178
Thanks, all the examples we've had so far didn't have variables so wasn't sure

>> No.12272417

>>12271700
Well it is a stupid questions thread. Instead of calling me a based Retard how about you answer my question.
But I am very Based thank you.

>> No.12272438

>>12272417
there's a difference between a stupid question and being retarded

>> No.12272510

>>12271696
How THE FUCK would we know?

>> No.12272528
File: 48 KB, 920x399, help.png [View same] [iqdb] [saucenao] [google] [report]
12272528

Can someone explain me what I am supposed to do here? I have problems understanding beams and moments.

>> No.12272572

>>12272528
you draw the forces at each point, and then set the sum of the x forces to zero, the sum of the y forces to zero, and the moments at each point to zero. that should give you a system you can solve

>> No.12272623

>>12269390
>>12269718
>>12270710

Anyone? I'd appreciate feedback.

>> No.12272703

>>12270710
>What I have slid in the code is the cell manipulating its environment, before the CA code is being run. This is unheard of, and kind of similar to a system creating a constraint / axiom which then builds the system.
Couldn't that be simulated with a more complicated update rule?
>One Turing strip overwrites the other Turing strip, which in turn changes the first Turing strip back. Pretty crazy huh?
Sounds just like a two-tape turing machine to me.
>This is not solving, it's modeling the solution for insight.
You mean they're only qualitatively similar and don't converge to the true solutions? I'm not sure that's actually true, I rembember hearing about a proof they did actually solve them.

>> No.12272725

>>12272572
how can get the moments?

>> No.12272729
File: 84 KB, 767x480, uhhhh.png [View same] [iqdb] [saucenao] [google] [report]
12272729

ive never seen a differential equation with hyperbolic solutions
pls explain

>> No.12272736
File: 9 KB, 264x264, 851.png [View same] [iqdb] [saucenao] [google] [report]
12272736

My formulae booklet failed me for the first time.

How much energy do I get from burning paraffin and what would be the comfiest way of converting it into electricity?

>> No.12272795

>>12272528
The force at A is [0,-150g]. The force at B must be perpendicular to the beam (it's a roller, so there's no parallel component). Note that the triangle is 3:4:5 so sin(θ)=3/5, cos(θ)=4/5. So you have 3 variables: |B|, C_x and C_y. The sum of the x components is zero, the sum of the y components is zero, the moment about any point is zero, so that's 3 equations.

>>12272572
You only need the moment about one point.

>> No.12272849

>>12272729
The solution of a system of linear ODEs is a sum of terms of the form t^(n-1).e^kt where k is a root of the characteristic polynomial and n is the multiplicity of that root. For a polynomial without repeated roots, all terms are of the form e^kt (i.e. n=1).

sinh(x)=(e^x-e^-x)/2, cosh(x)=(e^x+e^-x)/2 => e^x = cosh(x)+sinh(x), e^-x = cosh(x)-sinh(x).

If the characteristic polynomial is x^2-4k^2=0 (no first-order term) => x^2-(2k)^2=0 => x^2=(2k)^2, the roots are x=±2k, so you have e^2kx and e^-2kx terms. ae^2kx+be^-2kx = a(cosh(2kx)+sinh(2kx))+b(cosh(2kx)-sinh(2kx)) = (a+b)cosh(2kx)+(a-b)sinh(2kx).

>> No.12272857

>>12272703
>Couldn't that be simulated with a more complicated update rule?
I don't know. But the beauty is in its simplicty imo. The code is in the lain chan thread btw.
>Sounds just like a two-tape turing machine to me.
There is no storage tape in this setup. The tape is the storage.
>I rembember hearing about a proof they did actually solve them.
Navier-Stokes is a million dollar problem, I'm sure I would've heard if it was solved.

>> No.12272906
File: 303 KB, 1315x2048, __hakurei_reimu_touhou_drawn_by_nikorashi_ka__b8dfb17cd5eeeed8a38469af42adaf8e.jpg [View same] [iqdb] [saucenao] [google] [report]
12272906

>>12272857
The phrasing is weird, but, judging from context, he could be referring to a numerical scheme that's proven to converge to a solution whenever a solution exists.

>> No.12272948
File: 27 KB, 935x216, show A is an open set.jpg [View same] [iqdb] [saucenao] [google] [report]
12272948

How do I prove this?

>> No.12272964

>>12272438
Do you mind explaining why my post is retarded?

>> No.12272966

>>12272948
just show that its complement is a closed set bro

>> No.12272976

>>12272966
and how do I do that?

>> No.12272996

>>12272729
cosh(x) = cos(ix)
sinh(x) = i sin(ix)
the rest should follow

>> No.12272999

>>12272948
[math]l(x) = p \cdot x[/math] is continuous, hence [math]l^{-1}(- \infty, \beta)[/math] is open.
>>12272966
Retarded solution.

>> No.12273071

a matrix can have 0 for a nullity right?

>> No.12273075
File: 76 KB, 1238x568, open set.jpg [View same] [iqdb] [saucenao] [google] [report]
12273075

>>12272999
Thank you for your answer, but how can I prove it using this type of notations (pic related)?

I really need to prove this using vectors since it's the topic I'm studying right now.

>> No.12273113

>>12273075
We assume we're given a vector [math]a[/math] such that [math]p \cdot a = \gamma < \beta[/math]. Then, for some [math]b[/math], we estimate [math]p \cdot b = p \cdot (b-a) + p \cdot a = p \cdot (b - a) + \gamma \leq \|p \| \|b - a\| + \gamma[/math]. We want [math]p \cdot b \leq \beta [/math], so we choose [math]\|b - a \| < \frac{\beta - \gamma}{ \|p \|}[/math]. That's the open ball you want.

>> No.12273127

>>12273071
Yes. For instance, all invertible matrices do.

>> No.12273138

>>12273127
Fuck I even knew that about the invertible matrices cause I saw the proof like a week ago. jesus christ my brain is falling apart.

Thank you.

>> No.12273168

>>12273113
Thank you very much, it seems to be the answer I was looking for. I'm going to work on it to make sure I've got it all figured out.

>> No.12273279
File: 12 KB, 132x134, descartes.png [View same] [iqdb] [saucenao] [google] [report]
12273279

Help please with a math problem:
Someone measured the circumference of the three inside circles and they add up to 116". I need to know the circumference of the outside circle. Can anyone tell me the answer?

>> No.12273469
File: 27 KB, 132x134, 1603667459715.png [View same] [iqdb] [saucenao] [google] [report]
12273469

>>12273279
Big circle radius equals small circle radius plus green line. Green line is https://www.quora.com/What-is-the-distance-between-the-centre-of-an-equilateral-triangle-and-any-of-its-vertices

>> No.12273471

>>12273469
Oh right, forgot to mention, but notice that the triangle's sides are two times the small circle's radius.

>> No.12273534

I am a brainlet and this might be simple for you guys but please help.

which theta of a chord (less than 180degrees), has the greatest difference in (circumference - diameter) in relation to a semicircle that shares the same area?

>> No.12273694

>>12265984
At some point in the future would it be possible to speed up the orbit of a planet (like mercury or venus) to shield earth from a devastating solar flare?

>> No.12273762

>>12273469
>>12273471
OK thanks, I got 83.27 using some rounding.
Seems right, my guess was about 77.

>> No.12273861

>>12268985
Just hide all furnigger posts and pray for god (who doesn't exist unfortunately) to have all furries tortured forever in Hell.

>> No.12273873

>>12273861
Furries are inherently high IQ.

>> No.12273889

>>12273873
This, I fucking love those guys and I might be turning into one myself if that fucker keeps on posting so I hope he doesn't.

>> No.12273923

>>12273873
>>12273889
Samefag butthurt furry. Inb4 you use HTML editing to post a "proof" that you're not the samefag. Furries are just one of those groups that "the bigots" should have just gone with their gut on and put into death camps as soon as they started popping up.

>> No.12273941
File: 12 KB, 334x82, Screen Shot 2020-10-25 at 9.55.20 PM.png [View same] [iqdb] [saucenao] [google] [report]
12273941

>>12273923
Cope.

>> No.12273956
File: 2 KB, 253x40, samefag.png [View same] [iqdb] [saucenao] [google] [report]
12273956

>>12273941
Stop pretending to be me. The jig is up. All that's left to do is cry and dilate now :(

>> No.12274057

>>12272906
My automaton is forced into an arrested end-state for any given probability distribution, You just need to sort the ferro-ferri-antiferro-paramagnetic types of magnetism (all coexist in the model except diamagnetism and I may be wrong about the last).

>> No.12274389
File: 1.78 MB, 3632x3346, Boulogne Sur Mer, debunked.jpg [View same] [iqdb] [saucenao] [google] [report]
12274389

I made this for a flat earth thread but it got pruned before I could post it.
Leaving it here for now. Maybe there will be another thread someday I can post it.

>> No.12274397 [DELETED] 
File: 1.78 MB, 3632x3346, Boulogne Sur Mer, debunked.jpg [View same] [iqdb] [saucenao] [google] [report]
12274397

>>12274389
Improved version without the cringeworthy errors

>> No.12274418
File: 1.89 MB, 3632x3346, Boulogne Sur Mer, debunked.jpg [View same] [iqdb] [saucenao] [google] [report]
12274418

>>12274389
Improved version without the cringeworthy errors

>> No.12274474

Would u guys recommend sitz-zeager’s book on pre-calculus or james stewart’s.
I’ve skimmed through the first chapters of both and in my uninformed opinion, the latter seems more robust than the former yet a lot of reviews across the internet bash stewart’s book as rushed and in many cases shallow so im completely lost.

>> No.12274712
File: 48 KB, 300x100, 179.png [View same] [iqdb] [saucenao] [google] [report]
12274712

Could 4chans banner placing alghoritm become sentient? This is by far the most common one I see, probably 1/4th of the time. How does it know??

>> No.12274760
File: 45 KB, 750x445, index.jpg [View same] [iqdb] [saucenao] [google] [report]
12274760

>>12274712
Listen to this post if you want to live. I'm going to tell you what you need to do.

Refresh the screen 100 times on your computer. Record how many times you saw that banner.
Then, change to a different computer. Do the same.
Report the results in this thread.

>> No.12274794

I know you must get this a lot, but why are we so sure that the model is right and we just can't see most of the mass in the universe?

Like, why did we even start being like, "But no, really, it has to be." instead of, "Whoa, well, i guess that's wrong,"? Did people really just assume that because the theory predicted it, that DEFINED how much mass was in the universe, and they had no real idea of the total before hand?

>> No.12275127

Lets say inbreeding occurs within a population and eventually the population becomes fixed for all dominant genes. Assuming that none of the dominant genes reduce fitness within the population, are there any risks from continuous incest to that population?

>> No.12275167

>>12275127
No genetic risks. But the second one of them coofs its all over.

>> No.12275248

Does this have a name:
>numerical integration with variable subinterval size, where the subinterval size is proportional to the derivative of the function
>I.E., sections of the function with slow rates of change (relatively flat) are approximated with larger rectangles
>areas with quicker rates of change are approximated with more, thinner rectangles

>> No.12275266
File: 2.14 MB, 500x214, 1579519488376.gif [View same] [iqdb] [saucenao] [google] [report]
12275266

why don't blimps use vacuum
it should weight nothing, which means it's lighter than helium, no?

>> No.12275278
File: 390 KB, 749x542, bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.png [View same] [iqdb] [saucenao] [google] [report]
12275278

>>12275248

>> No.12275298

Is Fubini's Theorem essentially saying, "Iterated integration is commutative only when the bounds are symmetric"?

>> No.12275334

Is there a length at which the minimum energy in the quantum field everywhere would force there to always exist black holes? I don't mean exist for a moment and instantly evaporate, i mean constantly trying to evaporate but unable to faster that it gets energy from the quantum field, and couldnt all of space be full of them at this scale if they can exist?

>> No.12275354

>>12270003
she appeared in the first chapter of CoLA, so she gets the "EoSD treatment "

>> No.12275388
File: 174 KB, 331x307, dlanor.png [View same] [iqdb] [saucenao] [google] [report]
12275388

Hello lads
Anyone know a good book on topics of canonical formalism (Dirac Bracket, first and second class constraints)?
I already read my Goldstein and have some background on tangent spaces

>> No.12275793

For a matrix A, if i want to talk about the first row is it mathematically accept to say [math]A_{1}[/math] similar to how you would say [math]A_{11}[/math] for the 1st row 1st column entry?

>> No.12275889

Quick yes/no question:

Consider [math]\left (\prod_{i=1}^{n} x_i \right ) \bmod m[/math] where [math]m,x_i[/math] are some integers. Is it equal to [math]\left ( \prod_{i=1}^{n} (x_i \bmod m) \right ) \bmod m[/math]? i.e. can I push the modulo inside like this?

>> No.12275899

>>12275793
Usually, you use asterisks [math]a_i,_*[/math] is the ith row and [math]a_*,_j[/math] is the jth column.

>> No.12275907

>>12275899
thanks

>> No.12275908

>>12273873
you're thinking of white and asian mtf trannies. furfags are low iq. the enginigger furfag is a rare exception and still says retarded shit fairly frequently.

>> No.12275914

i have heard of a new scientific breakthrough for growing back teeth
unfortunately i have to have a tooth pulled and im very sad about that
theres going to be nothing there, but im wondering if that will make a difference for when this comes out will my tooth still be able to grow back? id assume so but idk
i just want hope

>> No.12275924

>>12275914
you can get an implant in the mean time. its low tech and slow to finish but it works.

>> No.12275943

>>12275924
i have heard that those usually dont work well in the back, which is where mine is.
im not so upset about it having to be pulled as i am probably because i wish i had taken better care of my teeth in the past, feels like im losing an arm even though i really dont even need that one
i wish i knew back then as a child

>> No.12275947
File: 3.41 MB, 1905x3458, __miyako_yoshika_touhou_drawn_by_mizoreshi__05d490a1839fdf7551fc1887b975a797.jpg [View same] [iqdb] [saucenao] [google] [report]
12275947

>>12275889
Yes.
>>12275908
>still says retarded shit fairly frequently
Everyone here says retarded shit frequently.

>> No.12276051
File: 51 KB, 559x178, matrix.png [View same] [iqdb] [saucenao] [google] [report]
12276051

Can someone tell what I need to do exactly in this one?

>> No.12276066

>>12275248
Adaptive quadrature?

BTW, assuming trapezoidal integration, it's the second derivative you should be looking at. More generally, if you're approximating the function with a degree-n polynomial, the (n+1)th derivative gives you an estimate of how well the approximation fits.

>> No.12276100

>>12275266
The vacuum is light, but a chamber that can hold it without imploding or leaking is really heavy.

>> No.12276131

Can I get a hint for this?

Given [math]n,m \in \mathbb{Z}[/math], show that the subgroup (w.r.t. [math](\mathbb{Z}, +)[/math]) generated by [math]\{n,m\}[/math] is precisely [math]d \mathbb{Z}[/math], where [math]d=\gcd(n,m)[/math].

I know that [math]\langle \{n,m\} \rangle = \{ xn+ym \mid x,y \in \mathbb{Z} \}[/math], not sure how to proceed.

>> No.12276140

>>12275266
It would get crushed by atmospheric pressure

>> No.12276199
File: 138 KB, 1024x1023, Bear Defense Armor.jpg [View same] [iqdb] [saucenao] [google] [report]
12276199

>>12265984
Okay, I figure this is a stupid question, and health/physiology is definitely a subsection of science. But lemme know if I'm out of place. (I'm a software dev is that means anything lmao). Its sex related, but a genuine question I'm planning on asking my doctor, and I figured I'd post here before somewhere like reddit.

Recently I noticed my dick seems to have partial numbness when I fuck, and I'm at a complete loss as to what is causing it. There was no pain associated with the incident, at least that I can recall. My dick did go somewhat numb the previous time (when I was throatfucking), but it was indistinguishable from being really hard/turned on. There was no pain, or lingering tingling or anything like that.

I have no bruising, no visual scarring, no bending (originally thought maybe peyrione's). No visual indicators and I'm not posting a pic to keep this SFW.

Does anyone have any idea wtf this could be? Going partially numb in the dick is causing me genuine psychological anguish and I want to do whatever it takes to get this fixed. Will it heal over time?

This is a genuine question, and if you guys have any additional questions, just cause. Googling just gets me horror images of dicks bent backwards, when my dick looks visually completely normal.

>> No.12276213

>>12276140
what if there was only a single molecule of gas in the chamber, and it was at such a high temperature that the pressure was equal to the outside pressure?

>> No.12276214

>>12276199
was she ugly?

>> No.12276230

>>12273113
Why p⋅b should be lower or equal to β?

>> No.12276233

>>12276214
Lol that's a great question. No she is not.

I can still get rock hard without stimulation seeing her naked, but then the touching happens and its like "wow, my dick has maybe 50% sensation, this sucks".

This is why I'm at a total loss. No bruising, no erection issues, can still ejaculate. Its literally just my dick being way less sensative, in a vaguely "damaged" sort of way. Is a pinched nerve in your dick possible? Wtf would you even do to fix that?

>> No.12276242

Let [math]a,x_0\in\mathbb{R}[/math] with [math]X_0>a[/math], an let [math]p:\mathbb{R}\to\mathbb{R}[/math] be a polynomial with degree [math]n\geq 2[/math], with [math]p(x)>0[/math] for all [math]x>a[/math]. I need to prove that
[math]
\dot{x}(t)=p(x(t)), \quad x(0)=x_0
[/math]
goes to infinity in finite time. Can somebody spoonfeed me this?

>> No.12276250

Are energies from sound waves additive? Specifically, if I have a stereo signal, i.e. two different waves, and I want the total energy, do I just get the energy from one wave, and add the energy from the other?
If not, how do I do it?

>> No.12276277

>>12276131
Note [math] x\in\langle n,m \rangle[/math] implies [math]x=an+bm[/math] hence [math]d|x[/math] so [math]x\in d\mathbb{Z}[/math]. Now [math]y\in d\mathbb{Z}[/math] i.e [math]y=td[/math] we know there exist [math]r,s[/math] so that [math]rn+ms=d[/math] so [math]rtn+stm=td=y[/math] so [math]y\in\langle n.m\rangle[/math] this proves the assertion by inclusion principle

>> No.12276282

>>12276213
The walls would cool it down and the pressure would drop. And/or the pressure would be so concentrated on the area that one particle is hitting that it would smash through the walls.

>> No.12276292

>>12276233
Did the Rabbi take your your foreskin?

>> No.12276307

>>12276250
Well you have to consider the new signal as the sum of the two waves and figure out the energy of that system, but i figure, yes! if we have a perfect system energy conservation tells us we have to add the energies, otherwise some energy must've been lost to heat as usual

>> No.12276323

>>12276277
Thanks a bunch! Bezout's identity is precisely what I was missing

>> No.12276328

>>12276292
Yeah but a long time ago. I highly doubt that is it. Was plenty sensitive before.

>> No.12276331

>>12276051
for a you can use the ERO [math]R_1\to\frac{1}{2}R_1[/math] and for b [math]R_1\to R_1+R_3[/math]

>> No.12276394

https://en.wikipedia.org/wiki/Conditional_random_field
In that definition of a CRF taken from the original article, the probability distribution is said to depend apart from the input on the values of all neighboring vertices, making the dependency graph undirected.
But in the applications of CRFs in PoS tagging, the distribution of the current tag depends on the previous tag only. Exactly where is the undirectedness in that? Am I misunderstanding the whole concept?

>> No.12276395 [DELETED] 

an object moves with constant acceleration and starts with the speed v_0 = 4 m/s
after 4s the object has moved 48m

what's the speed at -1s (minus one second)?
how long has the object moved when v = 8 m/s

>> No.12276416

>>12276395
the velocity at t=-1 is 0

>> No.12276445

I just got a job as an actuary. Am I /sci/ approved smart now?

>> No.12276458

>>12276445
You are much smarter than the retarded reddit undergrads that infest this board and likely above the failed tenure seekers and burned out grad students. You should be proud of yourself.

>> No.12276503

>>12276458
>t. reddit undergrad

>> No.12276585
File: 188 KB, 1439x859, Screenshot_20201026-170941_Firefox.jpg [View same] [iqdb] [saucenao] [google] [report]
12276585

>>12276445
this? youre probably smarter than most people, but youre not really "smart" smart.
congratulations, though

>> No.12276609

>>12276445
Nope, just 10% more kike than before
If you keep at it you might even be allowed into israel

>> No.12276685
File: 176 KB, 868x1228, __ibuki_suika_touhou_drawn_by_uu_uu_zan__0b7d88ff75136a373075c8ac73c83a3b.jpg [View same] [iqdb] [saucenao] [google] [report]
12276685

>>12276242
There is some [math]b \geq a[/math] such that [math]p(x) \geq cx^ 2[/math] for some constant [math]c > 0[/math]. Proving that there is such a [math]b[/math] and such a [math]c[/math] is left as an exercise to the reader. Showing that [math]b[/math] is reached in finite time is also left as an exercise.
Then, you can just compare with the differential equation [math]\dot{x}(t) = cx^2 (t)[/math], which is, by the by, a special case of your original problem.
Additional hint: Throw [math]y' = cy^2[/math] in WolframAlpha.
>>12276445
I don't know about /sci/ approved, but I'm not approving anyone without a Remilia folder.

>> No.12276688

>>12276685
*such that [math]p(x) \geq cx^2[/math] whenever [math]x \geq b[/math].

>> No.12276696

>>12276685
What equation most accurately describes the stink emanating from those 2hu armpits?

>> No.12276719

What sorts of job opportunities will I have if I get a PhD in nuclear engineering?

>> No.12276734

Classical mechanics books for undergrads?

>> No.12276793

Greetings, /sci/. I have a small doubt about relativity and time dilation.

Say, if there were to be two massive objects in space with a gravity force strong enough to dilate time in a meaningful way, but you were two stand right in the middle of the two objects (therefore making the net gravity force 0 due to each pulling to the other side), would you feel the time dilation? Double time dilation? None at all?

Thanks!

>> No.12276819

>>12276696
The constant zero function.

>> No.12276844

When using L'Hopital's rule, must I take the derivative of both the numerator and denominator, or can choose to do only the top or bottom?

>> No.12276847

>>12276844
you can only do le hospital if both the numerator and the denominator are inf, so it doesnt make sense that you could choose to only take the derivative of one of them, you have to do both

>> No.12276860
File: 221 KB, 996x1186, p1.png [View same] [iqdb] [saucenao] [google] [report]
12276860

why would two different, but presumably equivalent, coordinate representations of the same function get me different graphs here?

like you can represent a number in the complex plane with [math]x+iy[/math] and you can also represent it with [math]re^i\theta[/math] and cover the same space.

so why would these two surfaces be so different for what is essentially the same mapping?

>> No.12276870

>>12276847
>le hospital
haha
>you have to do both
Okay cool. For some reason I spontaneously developed the idea that I could show the limit of something like (n+1)/(2n+1) is zero by just differentiating the numerator down to 0 without touching the denominator, even though I've been using this rule for a while now.

>> No.12276871

>>12276847
You can also apply it if it's [math]\frac{0}{0}[/math].

>> No.12276885

>>12276860
Quite possibly the single dumbest question I've ever seen here.

>> No.12276914

>>12276885
But why though?

>> No.12276938

>>12276914
Do you think Wolfram can tell that r stands for radius and theta stands for angle? It's just assuming they're normal variables.

>> No.12276953

>>12276938
how do i tell wolfram that r stands for radius and theta stands for angle

has anyone informed mr wolfram of this terrible error

>> No.12276956

>>12276938
>Do you think Wolfram can tell that r stands for radius and theta stands for angle?
Yes.

>> No.12276985

>>12276953
Ask for a polar plot.

>> No.12276992

>>12276985
ah thank you

>> No.12277039

>>12276331
makes sense. Thanks anon

>> No.12277101

>>12276860
God damn it that's funny. Thank you for the laugh anon.

>> No.12277109

>>12276734
Kleppner & Kolenkow was good, has tough problems. Maybe not so good if you didn't do well in high school physics.

>> No.12277122

>>12277101
Cheers, lad.

>> No.12277170
File: 344 KB, 1024x923, 1603749795052~3.jpg [View same] [iqdb] [saucenao] [google] [report]
12277170

Do I have Autism?

>> No.12277294

>>12276734
taylor mechanics is the only book you need. about a 2nd/3rd year undergrad level

>> No.12277311

how do i write a statement of purpose in my grad school applications when the reason i'm going into math is "i think it's fun"

>> No.12277316

>>12277311
read a few essays on why fun and play is important, adapt it to your essay.

Just go whole hog with "I think it's fun" but if you can do it right, it will hit

>> No.12277318

>>12277316
That is something interesting I had not thought about. thank you for this advice.

>> No.12277354
File: 27 KB, 112x112, pepe_leaving_gif_apu_apustaja_never_come_back.gif [View same] [iqdb] [saucenao] [google] [report]
12277354

I am in my 4th year of my undergrad of a BA in mathematics and I no longer care about the subject. I can barely be bothered to graduate at the end of this year (if I do pass all my classes). I certainly have no interest in going to grad school.

I feel like I have some creativity bubbling beneath the surface but also feel trapped by needing to do assignments and attend online math society meetings and honors seminars.

Given that covid has rendered the university experience ghey and cringe, would it make sense to drop out for a year and try to develop some personal projects for the future middling software development job I am inevitably bound for? Honestly I kind of just want to learn to paint. I'm going insane in this fuckign quarantien bulllshit

>> No.12277387

>>12277354
Honestly, I'd say stick with it. You've almost made it through, you just have to push through this year. This semester is pretty much over, and then you just have about 16 weeks left.

I know you think that you'll come back to it, but if you stop now, there's a very real chance you may never find the energy to return to school, and even if you do, it might take well over the year that you anticipate taking off. I withdrew from school, for what I thought would be a semester, for mental health reasons. That ended up being two years, and I definitely regret it. I should have stayed with it. Don't make the same mistake.

>> No.12277390

>>12277354
Learn a language or instrument.

>> No.12277504

>>12265984
I am having so fucking many problems with statics. My book fucking sucks ass. Can someone recommend me a statics book that is brainlet friendly, or easy, or simply isn't shit.

>> No.12277744

Recommendations for a book about how to write proofs? I'm looking to relearn some abstract algebra as a hobby but my proof writing isn't great.

>> No.12277799
File: 113 KB, 1200x1920, how-to-prove-it.jpg [View same] [iqdb] [saucenao] [google] [report]
12277799

>>12277744

>> No.12278421
File: 30 KB, 631x368, bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.png [View same] [iqdb] [saucenao] [google] [report]
12278421

am I retarded or did my professor make a mistake in the lecture notes converting this cartesian equation to polar coordinates?
I keep on getting r(1-r), not r(1-r^2)

>> No.12278452

>>12278421
It is right x^2+y^2=r^2 and not r

>> No.12278456
File: 36 KB, 494x252, fields.png [View same] [iqdb] [saucenao] [google] [report]
12278456

Would the induced emf in this case be clockwise or anticlockwise?

>> No.12278539

>>12278456
There won't be an induced EMF around the loop as the flux enclosed by the loop never changes. On both sides of the loop, the induced field is upward (force on electrons downward), i.e. the top of the loop is positive, the bottom negative. Because the field is uniform, the field on both sides is equal and has opposite orientation (clockwise on the left, counter-clockwise on the right), so the net EMF around the loop is zero.

>> No.12278549

>>12278539
Yeah I got it wrong, first time trying to visualise 3D space with these questions and it's fucking me up..

>> No.12278559

>>12278549
>He can't visualize donuts flying through a magnetic field in 3d space
Gay

>> No.12278563

>>12278559
I know right? Fuck me man, my self esteem has been reduced to brainlet tier off this one subject this past week. I'm actually seething.

>> No.12278741

I just want to clarify
When they say [math]\zeta(-2)[/math] is a trivial zero of the riemann zeta fn, does that literally mean [math]\zeta(-2)=0[/math]?

>> No.12278785

If I have [math] P(A|B)[/math] and [math]P(A^c|B^c)[/math], how would I go about finding [math] P(A) [/math] and [math]P(B)[/math]?

>> No.12278814

>>12277170
Nah, just low intelligence for not understanding directions

>> No.12278849

[math]\lnot{X}\iff{Y}[/math]
assuming this is true then
does it mean X is equivalent to notY? Do I just have to make a truth table where notX and Y have identical values and then for X and notY?

>> No.12278874

>>12278785
That's not enough information to determine P(B), and in most cases not enough to determine P(A).

>> No.12278946

>>12278874
hmmm I see, then what about [math] P(B|A^c)[/math]?

>> No.12278968

>>12278741
Yes.

>> No.12279081

Analysis time.

Prove that if set [math]A[/math] is compact and nonempty, then [math]\sup(A)[/math] and [math]\inf(A)[/math] both exist and belong to [math]A[/math].

What I did:
1) Since [math]A[/math] is compact, it is closed and bounded.
2) Since [math]A[/math] is bounded, all its elements are bounded above and below and both [math]\sup(A)[/math] and [math]\inf(A)[/math] exist by completeness.
3) Since [math]A[/math] is closed, [math]A^c[/math] is open.
4) Let [math]b[/math] be an upper bound of [math]A[/math] that is not [math]\sup(A)[/math]. There always exists an epsilon-neighborhood of [math]b[/math] that is contained in [math]A^c[/math] because [math]A^c[/math] is open. I have that [math]\sup(A)[/math] is the only upper bound that has no epsilon neighborhood contained in [math]A^c[/math]. Therefore [math]\sup(A) \notin A^c[/math] then [math]\sup(A) \in A[/math].
5) Similar argument to (4) for [math]\inf(A)[/math].

I feel this is clunky

>> No.12279154
File: 1.09 MB, 1278x1600, __izayoi_sakuya_touhou_drawn_by_raptor7__ae52ea61db5e6b091652eea2c035d1ed.jpg [View same] [iqdb] [saucenao] [google] [report]
12279154

>>12278849
Yes.
>>12279081
I don't recall if this result has a name proper, but for any upper bounded set [math]A[/math] and any [math]\epsilon > 0[/math], there is some [math]x \in A[/math] such that [math]x \geq \sup A + \epsilon[/math].
You can use this result to produce a sequence that converges to the supremum (specifically, produce a sequence that *should* converge to the supremum, and show that it *does in fact* converge to the supremum because of compactness.)

>> No.12279159

>>12279154
*[math]x \geq \sup A - \epsilon[/math]

>> No.12279174

>>12279154
You mean [math]\sup(A)-\epsilon \leq x \leq \sup(A)[/math]. In which case I get it.

>> No.12279196

>>12278968
is that not proof that [math]2\times\infty[/math], and all even multiples, equals 0?

>> No.12279220

>>12279196
No.

>> No.12279225

>>12279220
So it is? thank you.

>> No.12279417
File: 1.18 MB, 1000x1563, 1603818164327.png [View same] [iqdb] [saucenao] [google] [report]
12279417

This chart I've just gotten from >>12279120 is actual schizo nonsense on a level substantially worse than the older charts, should I add it to the imgur regardless?

>> No.12279450

>>12279417
Also, I want to mention that I'm fairly sure it is, in fact, new. See >>https://warosu.org/sci/image/BMbB0T9jFtr-5FZTgb4bSA

>> No.12279530

help a retard out /sci/

Consider a polygon on [math]p[/math] vertices for some prime [math]p[/math]. Suppose we pick two vertices and color one blue and the other red. Claim: "the polygon admits no symmetries". But... why? What does this actually mean? And what role does the primality of [math]p[/math] play here?

>> No.12279575
File: 1001 KB, 895x788, Screenshot_2020-10-27 Geothermal energy is poised for a big breakout.png [View same] [iqdb] [saucenao] [google] [report]
12279575

Do you guys think there will be hidden consequences if Geothermal energy becomes the next big clean energy source? Imagine if the world started filling up with these plants that used geothermal energy. It's basically pulling the heat out of the crust. I feel like that is going to have consequences.

>> No.12279580

I just missed a physics test because I thought it was tomorrow. I should still pass the class. Am I too stupid to be an engineer? Im 27 btw

>> No.12279584

>>12279580
sorry to hear that anon. you should email the professor and see if you cant work something out

>> No.12279603

>>12279584
I deserve it, I will still pass the class. I've been acting like a loser this semester.

>> No.12279605

>>12279575
I thought people already did the math and decided it wasn't sustainable

>> No.12279618

>>12279605
Well let's just say that it is viable and they start building a lot of them. I'm just wondering what would happen if we started sapping the heat out of the Earth's crust. It sounds like bad idea, but I'm not sure why.

>> No.12279690

>>12278785
>>12278946
any statsfags here who can help a retard?

>> No.12279750

Is my laptop some kind of model of the universal Turing machine?

>> No.12279787

>>12278785
[math]P(A)=P(A|B^c)P(B^c)+P(A|B)P(B)[/math]
[math]P(A)=(1-P(A^c|B^c))P(B^c)+P(A|B)P(B)[/math]

Not sure if this is correct

>> No.12279809

>>12279787
You are correct but that only gives [math]P(A)[/math] as a function of [math]P(B)[/math]. Sadly, to fully solve the problem one would also need the conditional information [math]P(B \vert A)[/math] and [math]P(B \vert A^c)[/math]

>> No.12279858

>>12279809
could I find >>12278946 with only knowing >>12278785

?

>> No.12279875

>>12279858
Only with all four quantities, i.e. [math]P(A), P(B), P(A \vert B),[/math] and [math]P(A^c \vert B^c)[/math].

>> No.12279882

About wormholes (if they really exist), would the entrance / exit have a back side? If these are supposed to be connected, there should somehow be a tunnel between them, but since we are in 3D space, things get fuzzy in my mind...

>> No.12279938
File: 2.80 MB, 3277x4096, __saigyouji_yuyuko_touhou_drawn_by_gominami__21d34f15064d397ab8bd1e18fc2978bf.jpg [View same] [iqdb] [saucenao] [google] [report]
12279938

>>12279530
>What does this actually mean?
It means symmetries of the polygon that fix the vertices's colours.
>And what role does the primality of p play here?
Pretty sure it just means [math]p[/math] is odd.
Your professor could be intending for you guys to exploit Lagrange, tho.

>> No.12279961

Dumbo here. I'm working on a project and need to find information on robot grippers. Specifically something that I could use as filthy undergraduate scum.
Thanks.

>> No.12280071
File: 90 KB, 1051x922, bros.png [View same] [iqdb] [saucenao] [google] [report]
12280071

Bros, what type of math is this and how do I learn it

>> No.12280078

>>12280071
calc III + linear algebra + advanced classical mechanics

>> No.12280184

>>12280078
Only done calc 2, basic matrices and vectors, and basic mechanics. How long will it take to get my math knowledge there?

>> No.12280197

I know what cos and sin do but idk where to apply them

>> No.12280229

>>12280197
Pretty much any place where (right) triangles are involved.

>> No.12280235

>>12280229
If i shoot a bullet and it curves downwards over time, where is the right triangle in that?

>> No.12280273

>>12279417
Meds status : Not taken

>> No.12280276
File: 69 KB, 692x1024, 1593595056028.jpg [View same] [iqdb] [saucenao] [google] [report]
12280276

with triple intergrals, how to know which coordinates system to change to, sometimes its obvious like if im given a hemisphere but the question is in cartesian coordinates obviously id change to spherical coordinates but im just doing that with some vague intuition, I dont understand what im doing, is there some rule or something?

>> No.12280466

>>12280276
Wild guessing and random intuition. You can also try to predict how to make terms cancel out in your head.
There are really no rules.

>> No.12280542

>>12280235
the initial angle that you fired the bullet can be used to construct a right triangle
from this triangle, you use sin and cos to get the horizontal and vertical components of the velocity
you use the vertical velocity, along with kinematics equations, to calculate when the bullet will come back to the ground

>> No.12280546

>>12280184
time? it purely depends on your dedication
you can do calc III + linear algebra in around half a year or less with moderate commitment. advanced mechanics depends on your amount of background in mechanics, but probably another two months

>> No.12280643

So listening to the oil bit in the presidential debate got me thinking how viable a transition from oil would be as things stand. We might be able to adopt electric cars but what would things like trucks, planes, military vehicles, ships? Is there a renewable fuel that you could use with existing engines?

>> No.12280659

im going to drop the engineering part of my course at the end of this year, I really enjoy studying maths though and id like to study further in my personal time but idk where to go next, currently I think im taking the american equivalent of calc 3, I think? for my aussie bros im taking ENG2005, I enjoy learning about ODE's and PDE's where do I go next?

>> No.12280662

>>12280643
these aren't usually what people mean when they make this claim. diverging from oil means doing so in the industries where we have viable alternatives. further research would need to be done to come up with non-gas powered airplanes.

>> No.12280683

>>12280662
What about trucks, tanks, ships? Is there anywhere else other than short range vehicles that renewable would be viable?

>> No.12280687 [DELETED] 
File: 85 KB, 500x350, Mitochondria.png [View same] [iqdb] [saucenao] [google] [report]
12280687

>In instances of interbreeding among identical species, the father's mitochondrial DNA
entered the egg via his sperm, but after a certain amount of time, it died out, presumably
neutralized by the placenta. In other words, the father's mitochondrial DNA was ultimately
not inherited by the birthed child. However, when different species were crossbred, the
opposite was true. The offspring's mitochondrial DNA was found to be 56% paternal.

Is this true?

>> No.12280692
File: 85 KB, 500x350, Mitochondria.png [View same] [iqdb] [saucenao] [google] [report]
12280692

>In instances of interbreeding among identical species, the father's mitochondrial DNA entered the egg via his sperm, but after a certain amount of time, it died out, presumably neutralized by the placenta. In other words, the father's mitochondrial DNA was ultimately not inherited by the birthed child. However, when different species were crossbred, the opposite was true. The offspring's mitochondrial DNA was found to be 56% paternal.

Is this true?

>> No.12280802

>>12278814
But I didn't cross a single line.

>> No.12281035

>>12271390

>> No.12281151

>>12280643
transition from oil is totally inevitable. it will hapen slowly over the next half century, probably.

>> No.12281160

Let [math]f: {\mathbb Z}^2 \to {\mathbb Z}^2[/math] where [math]f(x,y) = (28x + 38y,12x+16y)[/math]. What is the index of [math]\text{Im } f[/math]?

>> No.12281183

>>12280643
>>12280683
The limiting factor for electric propulsion is battery technology, but I don't think you are talking about electric motors. Any power generation from steam or internal combustion usually requires a fuel. All the best fuels are fossil fuels, unfortunately, but alcohol and biodiesel still exist. Steam can be produced with anything that combusts, including renewable lumber. Any other gas turbines or piston engines will need redesign/significant modification to run on alcohol or biodiesel.
Transition away from fossil fuels is inevitable, btw

>> No.12281217
File: 84 KB, 1280x720, sore_ga_seiyuu-02-ichigo-question_mark-confused-cute-chibi-pink_hair.jpg [View same] [iqdb] [saucenao] [google] [report]
12281217

Not sure where to ask it, so I'll ask here.
Is non-polygonal dynamic 3D modelling/shaping a thing?

So I had a weird dream, where algorithms that were initially used in astrophysics / geophysics simulations (in the dream they were called "terebs") became very popular in 3D imaging / modelling, simulation engines, manufacturing, gaming engines and all things VR related.
It allowed for dynamic modelling, shaping/reshaping of objects in a very resource efficient way and it was so well correlated to real life that people were designing instruments using it and checking out the sound in the sim / structural tensions of construction materials etc.
Not sure about the details, it didn't use polygons, but more like mimicked fluids/gas/spray to determine the shape of the objects, and it was originally used for astrophysics/geophysics simulations.

Anyone heard about something like this?

>> No.12281226

>>12281217
sounds similar to vector graphics

>> No.12281238

>>12281217
Tl;dr - golden nugget algos used in astrophysics/geophysics that were discovered to have 9999999 other uses.
Also in the dream people were confused when looking at it at first, "wtf does this even do, wtf is that?", until someone played with it for a bit and started to realize how many use cases it had.

>> No.12281317

>>12281226
>sounds similar to vector graphics

>Vector graphics editors typically allow translation, rotation, mirroring, stretching, skewing, affine transformations, changing of z-order (loosely, what's in front of what) and combination of primitives into more complex objects.
>More sophisticated transformations include set operations on closed shapes (union, difference, intersection, etc.).
>lossless
>efficient
Seems to be it. Thanks for the answer!
In the dream people could grab a point of an object, stretch it, resize it, edit it and it wouldn't affect the integrity/quality of / wouldn't bug out the structure of the object. So you could copy paste a piano 20 times, make slight edits to each copy (shape, size, inclanations, make a corner rounder or taller) and the modelled pianos would all still produce realistic sounds with no structural artifacts popping up, especially when editing/resizing curves. It does sound like vector graphics. The "terebs" somehow took it to the next level with 3D dynamic operations. Just a dream.

>> No.12281630

>>12280643
Any existing fossil fuel could be synthesised from plant sources; it's just a question of economics and land usage. In practice, you don't need to make perfect copies; the engines were designed around the fuels which were available, and you can modify the design to work with similar fuels. Most diesel engines don't even need to be redesigned; the whole point of the diesel engine was that it runs on less volatile fuels (most will run on vegetable oil with 5-10% ethanol to reduce viscosity).

For haulage, adding overhead cables to major highways has been suggested. It isn't quite as simple as for trains/trams because you don't have the rails as the other conductor; you'd need at least two cables.

Shipping could go nuclear, but the industry would need to become a lot less shady before that would be feasible.

>> No.12281729

>>12281183
>gas turbine or piston engine will need redesign/significant modification
So it's already pretty complicated since most of the world runs on those, doesn't it.
>>12281151
>next half century
that's what I'm asking though, is it reasonable to think that given how many industries will have to have engine design changes due to it
>>12281630
>most diesel engines
Does that include gas turbine engines variations used in planes? would that cover the needs of the military? should also cover trucks since they use diesel engines too, right
>shipping could go nuclear
lmao that's pretty far fetches, don't they have a lot of problems disposing of warships that are nuclear? and then, as you said, there's the issue of how many accidents they might have.

>> No.12281849

>>12269718
>>12270710
>>12272857
>>12274057

tl:dr need feedback on my Ising model presentation, thanks

lain chan / lambda / res/9558.html#19751

>> No.12281858

Guys, got any advice on how to select a good final year project? How do I find out which one would be best for the job market or for getting into an Msc/PhD.

>> No.12282012

>>12281729
> Does that include gas turbine engines variations used in planes? would that cover the needs of the military?
Jet fuel (kerosene) isn't exactly unique. It's just a mixture of hydrocarbons with specific performance properties. It isn't even a specific mixture; the actual composition can vary between brands and between batches. All of the hydrocarbons involved can be synthesised. If you were making jet fuel from plant sources, the end result would be dictated more by economics than by a desire to closely match the chemical composition of jet fuel made from crude oil.

>> No.12282198

Any good study guides or videos for basic HS chemistry? For some reason, I have to take take a chemistry placement test at this CC before I take General Chemistry I. I don't know why, the class covers everything anyway, I took chemistry in HS, and I know for a fact the state universities don't do this but it's whatever.

The thing is, I really don't remember my HS chemistry that well but taking some remedial CC-only chemistry course would set me back tremendously. Any advice?

>> No.12282238

>>12282012
I see, thanks for the response. When people talk about getting rid of oil do they mean using all electric or do they want to get rid of fuel from plant sources too?
Also do you have any resources for learning about fuel, mainly broad ideas, like composition and uses.

>> No.12282241

is there any simple intuitive way to understand why the fundamental theorem of algebra is true?
none of the proofs on wikipedia make sense to me

>> No.12282243

>>12282198
https://www.chemguide.co.uk/

>> No.12282300
File: 288 KB, 824x643, 1603897089.png [View same] [iqdb] [saucenao] [google] [report]
12282300

Hey /sci/, anyone good with probability/statistics?
I made something that works, but I don't know why it works.
I'm working on a program that needs a random number generator with correlated rayleigh distribution.
Numpy doesn't have this, so I set out to make my own.
What numpy DOES have is multivariate_normal(), which takes a covariance matrix and then returns random gaussian-distributed numbers that have a certain correlation.
To make a rayleigh distribution out of 2 normal distributions, you just do [math]\sqrt(a^2 \cdot b^2)[/math] on them, easy enough.

Problem:
When I tell the multivariate_normal() function to use a certain correlation, then after doing \sqrt(a^2 \cdot b^2) on them, the result no longer has the same correlation.

Solution:
Through sheer TRIAL AND ERROR, I found out that the following covariance matrix works ALMOST PERFECTLY (see pic) in all cases:
[math]\begin{bmatrix}
\sigma^2 & \sqrt{corr} \cdot \sigma^2\\
\sqrt{corr} \cdot \sigma^2 & \sigma^2
\end{bmatrix}[/math]

Now my question is: Why does this work?
Why does the factor [math]\sqrt{corr}[/math] for the covariance of the normal distribution result in a correlation coefficient of [math]corr[/math] between two rayleigh distributions?
>bonus question: Why is it only ALMOST perfect? When i ask for a correlation of 0.5 then after like 100,000 samples it converges to something like 0.48 instead

>> No.12282310

>>12282300
>you just do [math]\sqrt(a^2 \cdot b^2)[/math] on them

I meant [math]\sqrt{a^2 + b^2}[/math]

>> No.12282376

Consider the linear map
[math] \mathbb{R}^{m\times n} \to \mathbb{R}^{m \times l}: W \mapsto WB [/math], where [math] B \in \mathbb{R}^{n \times l} [/math]
Is its transpose [math] \mathbb{R}^{m \times l} \to \mathbb{R}^{m\times n}: K \mapsto KB^\top [/math]?

Similarly for
[math] \mathbb{R}^{n\times l} \to \mathbb{R}^{m \times l}: V \mapsto AV [/math], where [math] A \in \mathbb{R}^{m \times n} [/math].
Is its transpose [math] \mathbb{R}^{m \times l} \to \mathbb{R}^{n\times l}: H \mapsto A^\top H [/math]?

>> No.12282413

>>12282376
It might be clearer if you drew diagrams. Finite - dimensional vector spaces over any field form a compact closed category, and those have a nice graphical calculus.

>> No.12282467

>>12282413
I know jackshit category theory though.

>> No.12282501

>Verbitsky
Is this guy serious?

>> No.12282532
File: 168 KB, 1535x1654, __patchouli_knowledge_touhou_drawn_by_denaseey__a458dde29ff208639757f7d77c31fd62.jpg [View same] [iqdb] [saucenao] [google] [report]
12282532

>>12282376
Yeah, almost. You take the base for [math]\mathbb{R}^{m \times n}[/math] to be the [math]E_{i, j}[/math] matrices (has a one in line i, row j, zero everywhere else), and order them the normal way to get the [math]\mathbb{R}^ {m \times n} \rightarrow \mathbb{R}^{m \times l}[/math]matrix you're transposing, right?
That large matrix's transpose is the same as the Frobenius norm adjoint. We know this because the isomorphism induced by the base choice from earlier induces an isometry, and the euclidean adjoint is the transpose.
The Frobenius inner product can be computed by [math]A \cdot B = tr(A^T B)[/math], so we compute the transpose of [math]W \rightarrow WB[/math] by [math]WB \cdot K = tr((WB)^T K)= tr(B^T W^T K) = tr(B^T (W^T K))= B \cdot W^TK[/math]

>> No.12282539

>>12282376
I found a way to do it btw.
For example for the second case:
We have that AV = [AV(1) ... AV(l)]
So, just transform V with a column vector (columns on top of each other) and multiply by a block diagona matrix containing l copies of A.
The mapping becomes
V_flat |--> diag(A, ..., A) V_flat
l*n x 1 |--> lm x ln times l*n

The transpose of that is
W_flat |--> diag(A', ..., A') W_flat
lm x 1 |--> ln x lm times lm x 1

Where W_flat corresponds to W:=[W(1), ... W(m)]
So the mapping is equivalent to
W |--> A'W, just as it was hypothesized

>> No.12282542

>>12282532
do you take any stims or are you actually this autistic about math?

>> No.12282559
File: 3.42 MB, 1999x3264, __konpaku_youmu_and_konpaku_youmu_touhou_drawn_by_ametama_runarunaruta5656__d9facaa01dd35e349162f7c37f56bfe1.jpg [View same] [iqdb] [saucenao] [google] [report]
12282559

>>12282542
>taking stimulants
Also, I'm not even that autistic, I completely mixed up my inner products and duality pairings, I'm not sure if that thing even makes sense, but the thought of having to prove it directly makes me nauseous.

>> No.12282563

>>12282532
oh wow that's pretty neat
thanks!
>That large matrix's transpose is the same as the Frobenius norm adjoint.
I know that the adjoint with respect to the usual inner product (dot product) is equal to the conjugate transpose.
Is there a proof that shows the Forbenius inner product does the same but for matrices?

btw what do you think of this approach >>12282539 ? is it correct?

>> No.12282566

>>12282559
I was asking in general, how do you not get sick of doing math?

>> No.12282598

>>12282539
>W:=[W(1), ... W(m)]
should be W:=[W(1), ... W(l)]

>> No.12282601

>>12282563
>>That large matrix's transpose is the same as the Frobenius norm adjoint.
>I know that the adjoint with respect to the usual inner product (dot product) is equal to the conjugate transpose.
>Is there a proof that shows the Forbenius inner product does the same but for matrices?
I get the impression you're misunderstanding, so I'll reiterate. We have the vector space [math]M_{m, n}[/math] of m, n matrices, and it has the Frobenius inner product. By ordering the [math]E_{i, j}[/math] base, we get an isomorphism [math]M_{m, n} \rightarrow R^{mn}[/math]. If we consider [math]\mathbb{R}^{mn}[/math] to be equipped with the standard euclidean product, this map is actually orthogonal. So the transpose for [math]\mathbb{R}^{m, n}[/math] equals the euclidean adjoint for [math]\mathbb{R}^{m, n}[/math], and the euclidean adjoint equals the Frobenius adjoint because of the earlier isometry.
>btw what do you think of this approach >>12282539 ? is it correct?
I'm sorry, but my eyes glaze over when I try to look at it. It seems correct, tho.
>>12282566
No idea. Might get sick of it eventually.

>> No.12282774

>>12282601
I see, so flattening the matrix and taking the dot product is the same as taking the frobenius product and then flattening (and flattening is also an isomorphism, making it an isometry).

So, we can Define (?) the transpose of a matrix-to-matrix map as the transpose of the corresponding flattened-to-flattened map, when we flatten it afterwards.
RIght?

Btw, I think >>12282532 at the end should be:
T: W --> WB
<T(W), K> = <WB, K> = tr((WB)*K) = tr(B*W*K) = tr(W*KB*) = <W, KB*> ==> T*(K) = KB*

>> No.12282783

>>12282774
>when we flatten it afterwards.
I meant
>when we unflatten it afterwards

Like, we flatten, then we transpose, then we unflatten.

>> No.12282839

>>12282774
>RIght?
That's the idea, yeah.
>Btw, I think >>12282532 at the end should be:
>T: W --> WB
><T(W), K> = <WB, K> = tr((WB)*K) = >tr(B*W*K) = tr(W*KB*) = <W, KB*> ==> T*(K) = KB*
Yeah, big dyslexia on my part.

>> No.12282874

>>12282839
Last question:
about this part
>So, we can Define (?) the transpose of a matrix-to-matrix map as the transpose of the corresponding flattened-to-flattened map, when we flatten it afterwards.
do you know if there's a way to induce this rule, rather than straight up define it?

>> No.12282898
File: 11 KB, 155x443, Screenshot_1.png [View same] [iqdb] [saucenao] [google] [report]
12282898

I'm being given this table with pressure vs fugacity for propane at 380 K, and I am asked to comment on the fugacity that propane exhibits as a real gas vs as an ideal gas.

Is there anything more to it other than the fact that the higher the pressure, the more exaggerated the intermolecular forces become, hence the fugacity of the real gas straying further from 1?

>> No.12282929

>>12282874
>do you know if there's a way to induce this rule, rather than straight up define it?
Not really. Defining "transposing" is roughly the same as defining taking the adjoint. However, taking the adjoint requires having a metric.
To put in other terms, there are many, many ways of mapping your linear transformation on spaces of matrices into a matrix, and this depends on your base choice and affects the resulting transpose.

>> No.12283008

>>12282929
I see. I was trying to figure it out in terms of dual spaces, but my mind can't handle it :P
Thanks a lot for the help fren!

>> No.12283602

who contributed more to math peter scholze or grothendieck ?

>> No.12283876

>>12283602
Grothendieck by far.

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