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# /sci/ - Science & Math

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File: 2.58 MB, 2184x3276, __tokiko_touhou_drawn_by_hisha_kan_moko__56e992bcdeaa1a83213b4df4ac5705f0.jpg [View same] [iqdb] [saucenao] [google] [report]

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?
>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://4chan-science.fandom.com/wiki//sci/_Wiki
>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?
>where do I look up if the question has already been asked on /sci/?
>>/sci/
https://boards.fireden.net/sci/
>how do I optimize an image losslessly?
https://trimage.org/
https://pnggauntlet.com/

>attach an image
>if a question has two or three replies, people usually assume it's already been answered
>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/

 >> Anonymous Fri Oct 23 21:36:55 2020 No.12265993 File: 1.73 MB, 500x250, Complex_theta_animated1.gif [View same] [iqdb] [saucenao] [google] [report] >>12265984First for the Jacobi $\theta$ function.
 >> Anonymous Fri Oct 23 21:44:01 2020 No.12266017 File: 174 KB, 1446x2048, __cirno_touhou_drawn_by_kae_karee__5f7f15fb81a3c3e8406c84be2b4198f1.jpg [View same] [iqdb] [saucenao] [google] [report] >>12265993Based.Unanswered questions:Maths questions:>>12253153>>12256452>>12256864>>12259081>>12260413>>12261608Physics questions:>>12257237>>12259360Chemistry questions:>>12261033Engineering questions:>>12256864Biology questions:>>12251981>>12263455Stupid questions:>>12251006>>12252258>>12253832>>12254466>>12255820>>12256752>>12257520>>12261773 [No.]>>12265252 [Please.]
 >> Anonymous Fri Oct 23 22:00:45 2020 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?
 >> Anonymous Fri Oct 23 22:02:51 2020 No.12266072   File: 28 KB, 463x378, circuit6.png [View same] [iqdb] [saucenao] [google] [report] 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.
 >> Anonymous Fri Oct 23 22:04:52 2020 No.12266076 File: 28 KB, 463x378, circuit6.png [View same] [iqdb] [saucenao] [google] [report] 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.
 >> Anonymous Fri Oct 23 22:14:42 2020 No.12266103 >>12266069No 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.
 >> Anonymous Fri Oct 23 22:23:25 2020 No.12266121 >>12266103That 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?
 >> Anonymous Fri Oct 23 22:35:14 2020 No.12266139 >>12266121The 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.
 >> Anonymous Fri Oct 23 22:44:24 2020 No.12266166 >>12266139Ok 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.
 >> Anonymous Sat Oct 24 04:43:43 2020 No.12266950 >>12266076idk, 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.
 >> Anonymous Sat Oct 24 05:17:36 2020 No.12267033 File: 45 KB, 1327x768, Screenshot_20201024_041656.png [View same] [iqdb] [saucenao] [google] [report] >>12261033IUPAC Blue Book, section A-2https://www.acdlabs.com/iupac/nomenclature/79/r79_36.htm
 >> Anonymous Sat Oct 24 05:19:54 2020 No.12267043 First year geology student here (Europe). What can I expect career-wise?
 >> Anonymous Sat Oct 24 05:20:27 2020 No.12267045 >>12267033and section A3, A4 goes over unsaturated chains
 >> Anonymous Sat Oct 24 06:03:42 2020 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?
 >> Anonymous Sat Oct 24 07:04:08 2020 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?
 >> Anonymous Sat Oct 24 08:11:11 2020 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.
 >> Anonymous Sat Oct 24 08:48:11 2020 No.12267414 >>12267201Thevmeasured correlation is 0,the theoretical correlation is 1 . It's a very unlikely result though, the probability of it halves each time you flip.
 >> Anonymous Sat Oct 24 08:51:58 2020 No.12267423 >>12267414>The measured correlation is 0,the theoretical correlation is 1 .Wait a minute! Strike that. Reverse it. Thank you.
 >> Anonymous Sat Oct 24 10:33:16 2020 No.12267717 Where can I find how to solve the non homogenous legendre differential equation? $\frac{d}{dx}\left( (1-x^2)y'\right)+\left( l(l+1)-\frac{m^2}{1-x^2} \right)y$They all solve it for m=0 and then they don't say anything more. Maybe I'm missing something
 >> Anonymous Sat Oct 24 10:48:18 2020 No.12267779 best software/web app for fast sketching math equations? not a solver, more like a notebook substitute
 >> Anonymous Sat Oct 24 10:48:24 2020 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
 >> Anonymous Sat Oct 24 10:54:19 2020 No.12267814 >>12267780No.
 >> Anonymous Sat Oct 24 10:57:44 2020 No.12267832 >>12267201the pair of coins represent a single random variable with two outcomes. Define $(H,H)=1$$(T,T)=0$the sequence is presumably a Bernoulli process with $p=0.5$, in which realizations are independent.$Cov[X_n,X_k]=E[X_nX_k] - E[X_n]E[X_k] = E[X_n]E[X_k](1-1) = 0$
 >> Anonymous Sat Oct 24 11:07:07 2020 No.12267879   >>12267780if you add $cos(\pi n)$ and $-cos(\pi n)$ you get a trivial convergent sequence.
 >> Anonymous Sat Oct 24 11:12:12 2020 No.12267896 >>12267780Let $y_n$ diverge and $x_n$ converge$lim(y_n)=lim(y_n+x_n-x_n)=lim(y_n+x_n)-lim(x_n)$so the sum diverges
 >> Anonymous Sat Oct 24 11:16:41 2020 No.12267909 >>12267896excellent thanks
 >> Anonymous Sat Oct 24 11:57:56 2020 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.
 >> Anonymous Sat Oct 24 11:58:43 2020 No.12268158 When has repeated lockdowns ever worked?
 >> Anonymous Sat Oct 24 12:34:23 2020 No.12268296 File: 1.83 MB, 2785x1540, __konpaku_youmu_and_konpaku_youmu_touhou_drawn_by_pegashi__9d8fe311f6b4ce7ca8039defcafa24dc.jpg [View same] [iqdb] [saucenao] [google] [report] 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 remotelyRemotely what?
 >> Anonymous Sat Oct 24 12:37:10 2020 No.12268305 >>12268296>Remotely what?LewdI think my brain shortcircuited
 >> Anonymous Sat Oct 24 12:55:04 2020 No.12268366 File: 113 KB, 559x694, electric field.png [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Sat Oct 24 13:31:18 2020 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.
 >> Anonymous Sat Oct 24 13:39:30 2020 No.12268496 >>12268366The 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.
 >> Anonymous Sat Oct 24 13:39:32 2020 No.12268497 >>12268474assume we know the mass*
 >> Anonymous Sat Oct 24 13:44:16 2020 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 velocityOr 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.
 >> Anonymous Sat Oct 24 13:53:25 2020 No.12268540 >>12268474if you're talking about work done to the object, then you're correctwork-energy theorem
 >> Anonymous Sat Oct 24 14:06:40 2020 No.12268577 >>12268366because electric field can be thought of as "electric force per unit charge"
 >> Anonymous Sat Oct 24 14:15:32 2020 No.12268599 >>12268513>>12268540Thank you very much, I really appreciate it.
 >> Anonymous Sat Oct 24 14:55:08 2020 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?
 >> Anonymous Sat Oct 24 14:57:16 2020 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?
 >> Anonymous Sat Oct 24 15:24:48 2020 No.12268774 >>12265984For engineers. How did everybody did in their first year of engineering? I am in my first year and it sucks ass for me.
 >> Anonymous Sat Oct 24 15:34:25 2020 No.12268791 File: 6 KB, 254x161, line integrals.png [View same] [iqdb] [saucenao] [google] [report] 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.
 >> Anonymous Sat Oct 24 15:35:11 2020 No.12268794 >>12268774high all day drunk all night
 >> Anonymous Sat Oct 24 15:35:52 2020 No.12268796 >>12268774Pretty bad for me because of the corona and the professors are real bad with heavy accents and obvious disinterest.
 >> Anonymous Sat Oct 24 15:52:57 2020 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.
 >> Anonymous Sat Oct 24 16:07:17 2020 No.12268866 File: 657 KB, 2563x3288, 24128c0c4b63e1791b128c8877400788.jpg [View same] [iqdb] [saucenao] [google] [report] >>12268791If you know the field is conservative, then yes C1=C2=C3+C4=0>>12268774it only got worse>>12268714coca cola bottling company wants you to have cheap HRT>>12268705you 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 dropshttp://snowball.millersville.edu/~adecaria/DERIVATIONS/Rain.pdf
 >> Anonymous Sat Oct 24 16:10:43 2020 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 dropsThank 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...
 >> Anonymous Sat Oct 24 16:38:05 2020 No.12268952 >>12268866I 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?
 >> Anonymous Sat Oct 24 16:44:46 2020 No.12268971 File: 131 KB, 585x800, 9665c87485483ae1d6284f8fb47fa993.jpg [View same] [iqdb] [saucenao] [google] [report] >>12268952"Lurk moar."
 >> Anonymous Sat Oct 24 16:47:35 2020 No.12268985 >>12268971That doesn't answer my question.
 >> Anonymous Sat Oct 24 16:54:40 2020 No.12269012 >>12268866>field is conservativeJesus I can't believe I forgot about this, thanks king.
 >> Anonymous Sat Oct 24 16:59:12 2020 No.12269031 File: 81 KB, 1089x303, circulation.png [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Sat Oct 24 16:59:25 2020 No.12269032 >>12268952Not 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.
 >> Anonymous Sat Oct 24 17:00:41 2020 No.12269038 >>12269031if it is a closed loop, yes
 >> Anonymous Sat Oct 24 17:50:49 2020 No.12269194 >>12269032this is extremely unsettling
 >> Anonymous Sat Oct 24 18:41:46 2020 No.12269349 >>12269032This is extremely based.
 >> Anonymous Sat Oct 24 18:58:05 2020 No.12269390 Please respond.>>12257237
 >> Anonymous Sat Oct 24 19:20:44 2020 No.12269477 File: 243 KB, 501x354, 1585786656788.png [View same] [iqdb] [saucenao] [google] [report] 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.
 >> Anonymous Sat Oct 24 19:23:03 2020 No.12269484 >>12269390bro nobody knows how to even visit your shit linkalso what are we supposed to comment?
 >> Anonymous Sat Oct 24 19:48:57 2020 No.12269578 >>12269484You access it at lainchan dot org/lambda/ res/9558.html#19751
 >> Anonymous Sat Oct 24 19:53:49 2020 No.12269589 >>12269390I check the pdf and I don't really know what are you really trying to express anon. Give me a quick rundown.
 >> Anonymous Sat Oct 24 20:19:57 2020 No.12269642 File: 52 KB, 455x627, 2018-01-24 01_55_19.jpg [View same] [iqdb] [saucenao] [google] [report] >2*3*5*7*11*13*17*19 = 9,699,690What did G_d mean by this?
 >> Anonymous Sat Oct 24 20:29:41 2020 No.12269670 >>12269477Tie the mattress to your back first, then run at the wall and knock yourself out. You'll fall backwards onto the mattress.
 >> Anonymous Sat Oct 24 20:46:51 2020 No.12269718 File: 26 KB, 211x220, 1598297119505.jpg [View same] [iqdb] [saucenao] [google] [report] >>12269484I'd like to learn if my research is noteworthy and anything extra is a plus.>>12269589QRD>it's a cellular automaton>that takes a 2D grid>and through anisotropy evolves it into a final state of 1D arrays:111000111>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 expressiblethe model is surfing on the 0-1 quantum sphere in the pic related.Does it make sense?
 >> Anonymous Sat Oct 24 21:30:21 2020 No.12269817 File: 14 KB, 198x220, homogeneous_equations.png [View same] [iqdb] [saucenao] [google] [report] >>12265984PLEASE 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.
 >> Anonymous Sat Oct 24 21:33:39 2020 No.12269826 >>12269817I have a timer set for an hour and forty five minutes to give you the answer.
 >> Anonymous Sat Oct 24 22:01:14 2020 No.12269908 >>12269817A differential equation is homogenous if it can expressed in the form $y' = \frac{f(x,y)}{g(x,y)}$, where $\deg(f) = \deg(g)$.
 >> Anonymous Sat Oct 24 22:31:32 2020 No.12270003 >>12265984why are people so autistic about tokiko? I mean barely any other PC98 characters receive as much attention
 >> Anonymous Sat Oct 24 22:42:37 2020 No.12270030 File: 883 KB, 800x800, 1586981095332.jpg [View same] [iqdb] [saucenao] [google] [report] >>12269718This 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?
 >> Anonymous Sat Oct 24 22:43:24 2020 No.12270031 File: 165 KB, 850x1202, 30160b11617bb3d0c68187666cf7e8b4e.jpg [View same] [iqdb] [saucenao] [google] [report] Is anyone here really high or used to dealing with schizos?>>>/wsr/910572 needs your help. You just need to know basic calculus.
 >> Anonymous Sat Oct 24 22:47:28 2020 No.12270039 >>12270031What the hell is he doing?
 >> Anonymous Sat Oct 24 22:50:11 2020 No.12270047 >>12270039I have no idea.He seems to have deleted some of his posts, but the conclusion he reached is retarded, so he still needs help.
 >> Anonymous Sun Oct 25 00:57:16 2020 No.12270364 >>12269817Only I and II are homogeneous.>>12269908That'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).
 >> Anonymous Sun Oct 25 04:07:06 2020 No.12270710 File: 273 KB, 1200x720, nn quine.jpg [View same] [iqdb] [saucenao] [google] [report] >>12270030Well 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.
 >> Anonymous Sun Oct 25 07:17:18 2020 No.12271087 Does anyone have a reliable place where i can find an SPSS torrent?
 >> Anonymous Sun Oct 25 09:09:43 2020 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?
 >> Anonymous Sun Oct 25 09:19:46 2020 No.12271334 >>12271295I 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.
 >> Anonymous Sun Oct 25 09:27:14 2020 No.12271353 File: 3.67 MB, 4032x3024, 20201018_150116.jpg [View same] [iqdb] [saucenao] [google] [report] i literally have my bachelors in maths, and im tutoring a 15 year old. he sent me this question asking for helpi unironically have no idea how to solve it
 >> Anonymous Sun Oct 25 09:28:28 2020 No.12271355 >>12271353Start with a new phone
 >> Anonymous Sun Oct 25 09:36:31 2020 No.12271376 >>12271353Come on anon, this is not difficult.1. write down equation relating X to 54 angle + unknown 12. 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 24. use said relation to solve for X in either equation 1 or 2
 >> Anonymous Sun Oct 25 09:38:23 2020 No.12271380 >>12271376yeah, but it asks for geometric reasoningive never done geometry in my life
 >> Anonymous Sun Oct 25 09:40:50 2020 No.12271385 >>12271380you're a failure and should stop tutoring kidsit's beyond me how you got your bachelors
 >> Anonymous Sun Oct 25 09:41:41 2020 No.12271388 File: 500 KB, 1000x1320, 13788741c4c3da8688728f8ef68a7e688.jpg [View same] [iqdb] [saucenao] [google] [report] >>12271353$DE + EA = 2DBA = 2*(54 + X)$ and $DB + BA = 2DEA = 2*(26 + X)$. Since $DE + EA + AB + BD = 360$, you have $360 = 2*54+ 2*26 + 4X$.
 >> Anonymous Sun Oct 25 09:43:32 2020 No.12271390 if i have a shit diet should i be taking multivitamins? seen a lot of people say theyre pretty much useless
 >> Anonymous Sun Oct 25 09:47:51 2020 No.12271400 >>12271380Wait, 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 A2. in the same way "drag" point B up to C to get a similar angle X+54Finally, solve for X.
 >> Anonymous Sun Oct 25 10:39:48 2020 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.
 >> Anonymous Sun Oct 25 10:43:49 2020 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.
 >> Anonymous Sun Oct 25 10:45:19 2020 No.12271536 >>12271529of course, it's called crammingthat's why universities suck, they force you to cram shit all the time
 >> Anonymous Sun Oct 25 10:46:48 2020 No.12271542 >>12271529Completely fucking normal. You need to have good memory or actively work on old material to remember them.
 >> Anonymous Sun Oct 25 11:34:46 2020 No.12271646 the heck happened to scg? thread got deleted while i was asleep
 >> Anonymous Sun Oct 25 11:42:14 2020 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?
 >> Anonymous Sun Oct 25 11:43:35 2020 No.12271660 >>12271646Mysterious are the ways of janitorial staff.They're probably particularly peeved because of the new ads.
 >> Anonymous Sun Oct 25 11:50:53 2020 No.12271682
 >> Anonymous Sun Oct 25 11:51:15 2020 No.12271685 >>12271660niggers, the lot of them
 >> Anonymous Sun Oct 25 11:55:13 2020 No.12271696 File: 148 KB, 1011x1024, 1603380032442.jpg [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Sun Oct 25 11:56:13 2020 No.12271700 >>12271696based retard poster
 >> Anonymous Sun Oct 25 12:42:34 2020 No.12271879 File: 3 KB, 178x130, Screenshot 2020-10-25 164145.jpg [View same] [iqdb] [saucenao] [google] [report] if you have a matrix like pic related, does the rank equal 2 or 3 for x in reals?
 >> Anonymous Sun Oct 25 14:01:35 2020 No.12272167 >>12271879Rank 3 if x≠0, rank 2 if x=0.
 >> Anonymous Sun Oct 25 14:05:59 2020 No.12272178 >>12271879It's contingent on the value of x.
 >> Anonymous Sun Oct 25 14:07:53 2020 No.12272183 >>12272167>>12272178Thanks, all the examples we've had so far didn't have variables so wasn't sure
 >> Anonymous Sun Oct 25 15:12:15 2020 No.12272417 >>12271700Well 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.
 >> Anonymous Sun Oct 25 15:18:50 2020 No.12272438 >>12272417there's a difference between a stupid question and being retarded
 >> Anonymous Sun Oct 25 15:37:32 2020 No.12272510 >>12271696How THE FUCK would we know?
 >> Anonymous Sun Oct 25 15:40:58 2020 No.12272528 File: 48 KB, 920x399, help.png [View same] [iqdb] [saucenao] [google] [report] Can someone explain me what I am supposed to do here? I have problems understanding beams and moments.
 >> Anonymous Sun Oct 25 15:50:27 2020 No.12272572 >>12272528you 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
 >> Anonymous Sun Oct 25 16:03:48 2020 No.12272623 >>12269390>>12269718>>12270710Anyone? I'd appreciate feedback.
 >> Anonymous Sun Oct 25 16:25:10 2020 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.
 >> Anonymous Sun Oct 25 16:31:07 2020 No.12272725 >>12272572how can get the moments?
 >> Anonymous Sun Oct 25 16:32:37 2020 No.12272729 File: 84 KB, 767x480, uhhhh.png [View same] [iqdb] [saucenao] [google] [report] ive never seen a differential equation with hyperbolic solutionspls explain
 >> Anonymous Sun Oct 25 16:34:13 2020 No.12272736 File: 9 KB, 264x264, 851.png [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Sun Oct 25 16:46:25 2020 No.12272795 >>12272528The 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.>>12272572You only need the moment about one point.
 >> Anonymous Sun Oct 25 17:00:49 2020 No.12272849 >>12272729The 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).
 >> Anonymous Sun Oct 25 17:02:58 2020 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.
 >> Anonymous Sun Oct 25 17:17:02 2020 No.12272906 File: 303 KB, 1315x2048, __hakurei_reimu_touhou_drawn_by_nikorashi_ka__b8dfb17cd5eeeed8a38469af42adaf8e.jpg [View same] [iqdb] [saucenao] [google] [report] >>12272857The 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.
 >> Anonymous Sun Oct 25 17:30:26 2020 No.12272948 File: 27 KB, 935x216, show A is an open set.jpg [View same] [iqdb] [saucenao] [google] [report] How do I prove this?
 >> Anonymous Sun Oct 25 17:35:20 2020 No.12272964 >>12272438Do you mind explaining why my post is retarded?
 >> Anonymous Sun Oct 25 17:35:36 2020 No.12272966 >>12272948just show that its complement is a closed set bro
 >> Anonymous Sun Oct 25 17:37:13 2020 No.12272976 >>12272966and how do I do that?
 >> Anonymous Sun Oct 25 17:41:56 2020 No.12272996 >>12272729cosh(x) = cos(ix)sinh(x) = i sin(ix)the rest should follow
 >> Anonymous Sun Oct 25 17:42:17 2020 No.12272999 >>12272948$l(x) = p \cdot x$ is continuous, hence $l^{-1}(- \infty, \beta)$ is open.>>12272966Retarded solution.
 >> Anonymous Sun Oct 25 18:02:46 2020 No.12273071 a matrix can have 0 for a nullity right?
 >> Anonymous Sun Oct 25 18:03:47 2020 No.12273075 File: 76 KB, 1238x568, open set.jpg [View same] [iqdb] [saucenao] [google] [report] >>12272999Thank 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.
 >> Anonymous Sun Oct 25 18:12:10 2020 No.12273113 >>12273075We assume we're given a vector $a$ such that $p \cdot a = \gamma < \beta$. Then, for some $b$, we estimate $p \cdot b = p \cdot (b-a) + p \cdot a = p \cdot (b - a) + \gamma \leq \|p \| \|b - a\| + \gamma$. We want $p \cdot b \leq \beta$, so we choose $\|b - a \| < \frac{\beta - \gamma}{ \|p \|}$. That's the open ball you want.
 >> Anonymous Sun Oct 25 18:15:22 2020 No.12273127 >>12273071Yes. For instance, all invertible matrices do.
 >> Anonymous Sun Oct 25 18:17:56 2020 No.12273138 >>12273127Fuck 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.
 >> Anonymous Sun Oct 25 18:25:34 2020 No.12273168 >>12273113Thank 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.
 >> Anonymous Sun Oct 25 19:10:59 2020 No.12273279 File: 12 KB, 132x134, descartes.png [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Sun Oct 25 20:06:35 2020 No.12273469 File: 27 KB, 132x134, 1603667459715.png [View same] [iqdb] [saucenao] [google] [report] >>12273279Big 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
 >> Anonymous Sun Oct 25 20:07:37 2020 No.12273471 >>12273469Oh right, forgot to mention, but notice that the triangle's sides are two times the small circle's radius.
 >> Anonymous Sun Oct 25 20:29:53 2020 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?
 >> Anonymous Sun Oct 25 21:15:44 2020 No.12273694 >>12265984At 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?
 >> Anonymous Sun Oct 25 21:38:44 2020 No.12273762 >>12273469>>12273471OK thanks, I got 83.27 using some rounding. Seems right, my guess was about 77.
 >> Anonymous Sun Oct 25 22:21:18 2020 No.12273861 >>12268985Just hide all furnigger posts and pray for god (who doesn't exist unfortunately) to have all furries tortured forever in Hell.
 >> Anonymous Sun Oct 25 22:24:44 2020 No.12273873 >>12273861Furries are inherently high IQ.
 >> Anonymous Sun Oct 25 22:31:50 2020 No.12273889 >>12273873This, 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.
 >> Anonymous Sun Oct 25 22:46:31 2020 No.12273923 >>12273873>>12273889Samefag 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.
 >> Anonymous Sun Oct 25 22:55:31 2020 No.12273941 File: 12 KB, 334x82, Screen Shot 2020-10-25 at 9.55.20 PM.png [View same] [iqdb] [saucenao] [google] [report] >>12273923Cope.
 >> Anonymous Sun Oct 25 23:05:19 2020 No.12273956 File: 2 KB, 253x40, samefag.png [View same] [iqdb] [saucenao] [google] [report] >>12273941Stop pretending to be me. The jig is up. All that's left to do is cry and dilate now :(
 >> Anonymous Mon Oct 26 00:04:17 2020 No.12274057 >>12272906My 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).
 >> Anonymous Mon Oct 26 03:15:59 2020 No.12274389 File: 1.78 MB, 3632x3346, Boulogne Sur Mer, debunked.jpg [View same] [iqdb] [saucenao] [google] [report] 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.
 >> Anonymous Mon Oct 26 03:22:40 2020 No.12274397   File: 1.78 MB, 3632x3346, Boulogne Sur Mer, debunked.jpg [View same] [iqdb] [saucenao] [google] [report] >>12274389Improved version without the cringeworthy errors
 >> Anonymous Mon Oct 26 03:33:43 2020 No.12274418 File: 1.89 MB, 3632x3346, Boulogne Sur Mer, debunked.jpg [View same] [iqdb] [saucenao] [google] [report] >>12274389Improved version without the cringeworthy errors
 >> Anonymous Mon Oct 26 04:19:45 2020 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.
 >> Anonymous Mon Oct 26 06:50:09 2020 No.12274712 File: 48 KB, 300x100, 179.png [View same] [iqdb] [saucenao] [google] [report] 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??
 >> Anonymous Mon Oct 26 07:22:52 2020 No.12274760 File: 45 KB, 750x445, index.jpg [View same] [iqdb] [saucenao] [google] [report] >>12274712Listen 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.
 >> Anonymous Mon Oct 26 07:49:53 2020 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?
 >> Anonymous Mon Oct 26 11:31:02 2020 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?
 >> Anonymous Mon Oct 26 11:47:19 2020 No.12275167 >>12275127No genetic risks. But the second one of them coofs its all over.
 >> Anonymous Mon Oct 26 12:10:51 2020 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
 >> Anonymous Mon Oct 26 12:15:01 2020 No.12275266 File: 2.14 MB, 500x214, 1579519488376.gif [View same] [iqdb] [saucenao] [google] [report] why don't blimps use vacuum it should weight nothing, which means it's lighter than helium, no?
 >> Anonymous Mon Oct 26 12:17:37 2020 No.12275278 File: 390 KB, 749x542, bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.png [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Mon Oct 26 12:22:26 2020 No.12275298 Is Fubini's Theorem essentially saying, "Iterated integration is commutative only when the bounds are symmetric"?
 >> Anonymous Mon Oct 26 12:30:43 2020 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?
 >> Anonymous Mon Oct 26 12:36:08 2020 No.12275354 >>12270003she appeared in the first chapter of CoLA, so she gets the "EoSD treatment "
 >> Anonymous Mon Oct 26 12:43:12 2020 No.12275388 File: 174 KB, 331x307, dlanor.png [View same] [iqdb] [saucenao] [google] [report] Hello ladsAnyone 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
 >> Anonymous Mon Oct 26 14:34:58 2020 No.12275793 For a matrix A, if i want to talk about the first row is it mathematically accept to say $A_{1}$ similar to how you would say $A_{11}$ for the 1st row 1st column entry?
 >> Anonymous Mon Oct 26 15:00:40 2020 No.12275889 Quick yes/no question:Consider $\left (\prod_{i=1}^{n} x_i \right ) \bmod m$ where $m,x_i$ are some integers. Is it equal to $\left ( \prod_{i=1}^{n} (x_i \bmod m) \right ) \bmod m$? i.e. can I push the modulo inside like this?
 >> Anonymous Mon Oct 26 15:04:38 2020 No.12275899 >>12275793Usually, you use asterisks $a_i,_*$ is the ith row and $a_*,_j$ is the jth column.
 >> Anonymous Mon Oct 26 15:06:08 2020 No.12275907 >>12275899thanks
 >> Anonymous Mon Oct 26 15:06:56 2020 No.12275908 >>12273873you'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.
 >> Anonymous Mon Oct 26 15:08:35 2020 No.12275914 i have heard of a new scientific breakthrough for growing back teethunfortunately i have to have a tooth pulled and im very sad about thattheres 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 idki just want hope
 >> Anonymous Mon Oct 26 15:13:20 2020 No.12275924 >>12275914you can get an implant in the mean time. its low tech and slow to finish but it works.
 >> Anonymous Mon Oct 26 15:20:49 2020 No.12275943 >>12275924i 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 onei wish i knew back then as a child
 >> Anonymous Mon Oct 26 15:21:27 2020 No.12275947 File: 3.41 MB, 1905x3458, __miyako_yoshika_touhou_drawn_by_mizoreshi__05d490a1839fdf7551fc1887b975a797.jpg [View same] [iqdb] [saucenao] [google] [report] >>12275889Yes.>>12275908>still says retarded shit fairly frequentlyEveryone here says retarded shit frequently.
 >> Anonymous Mon Oct 26 15:54:20 2020 No.12276051 File: 51 KB, 559x178, matrix.png [View same] [iqdb] [saucenao] [google] [report] Can someone tell what I need to do exactly in this one?
 >> Anonymous Mon Oct 26 15:57:03 2020 No.12276066 >>12275248Adaptive 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.
 >> Anonymous Mon Oct 26 16:09:48 2020 No.12276100 >>12275266The vacuum is light, but a chamber that can hold it without imploding or leaking is really heavy.
 >> Anonymous Mon Oct 26 16:18:24 2020 No.12276131 Can I get a hint for this?Given $n,m \in \mathbb{Z}$, show that the subgroup (w.r.t. $(\mathbb{Z}, +)$) generated by $\{n,m\}$ is precisely $d \mathbb{Z}$, where $d=\gcd(n,m)$.I know that $\langle \{n,m\} \rangle = \{ xn+ym \mid x,y \in \mathbb{Z} \}$, not sure how to proceed.
 >> Anonymous Mon Oct 26 16:20:24 2020 No.12276140 >>12275266It would get crushed by atmospheric pressure
 >> Anonymous Mon Oct 26 16:31:31 2020 No.12276199 File: 138 KB, 1024x1023, Bear Defense Armor.jpg [View same] [iqdb] [saucenao] [google] [report] >>12265984Okay, 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.
 >> Anonymous Mon Oct 26 16:34:41 2020 No.12276213 >>12276140what 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?
 >> Anonymous Mon Oct 26 16:35:30 2020 No.12276214 >>12276199was she ugly?
 >> Anonymous Mon Oct 26 16:39:59 2020 No.12276230 >>12273113Why p⋅b should be lower or equal to β?
 >> Anonymous Mon Oct 26 16:40:56 2020 No.12276233 >>12276214Lol 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?
 >> Anonymous Mon Oct 26 16:43:39 2020 No.12276242 Let $a,x_0\in\mathbb{R}$ with $X_0>a$, an let $p:\mathbb{R}\to\mathbb{R}$ be a polynomial with degree $n\geq 2$, with $p(x)>0$ for all $x>a$. I need to prove that $\dot{x}(t)=p(x(t)), \quad x(0)=x_0$goes to infinity in finite time. Can somebody spoonfeed me this?
 >> Anonymous Mon Oct 26 16:44:57 2020 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?
 >> Anonymous Mon Oct 26 16:52:37 2020 No.12276277 >>12276131Note $x\in\langle n,m \rangle$ implies $x=an+bm$ hence $d|x$ so $x\in d\mathbb{Z}$. Now $y\in d\mathbb{Z}$ i.e $y=td$ we know there exist $r,s$ so that $rn+ms=d$ so $rtn+stm=td=y$ so $y\in\langle n.m\rangle$ this proves the assertion by inclusion principle
 >> Anonymous Mon Oct 26 16:53:28 2020 No.12276282 >>12276213The 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.
 >> Anonymous Mon Oct 26 16:55:45 2020 No.12276292 >>12276233Did the Rabbi take your your foreskin?
 >> Anonymous Mon Oct 26 16:59:48 2020 No.12276307 >>12276250Well 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
 >> Anonymous Mon Oct 26 17:05:01 2020 No.12276323 >>12276277Thanks a bunch! Bezout's identity is precisely what I was missing
 >> Anonymous Mon Oct 26 17:06:22 2020 No.12276328 >>12276292Yeah but a long time ago. I highly doubt that is it. Was plenty sensitive before.
 >> Anonymous Mon Oct 26 17:07:05 2020 No.12276331 >>12276051for a you can use the ERO $R_1\to\frac{1}{2}R_1$ and for b $R_1\to R_1+R_3$
 >> Anonymous Mon Oct 26 17:23:19 2020 No.12276394 https://en.wikipedia.org/wiki/Conditional_random_fieldIn 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?
 >> Anonymous Mon Oct 26 17:23:28 2020 No.12276395   an object moves with constant acceleration and starts with the speed v_0 = 4 m/safter 4s the object has moved 48mwhat's the speed at -1s (minus one second)?how long has the object moved when v = 8 m/s
 >> Anonymous Mon Oct 26 17:32:07 2020 No.12276416 >>12276395the velocity at t=-1 is 0
 >> Anonymous Mon Oct 26 17:39:02 2020 No.12276445 I just got a job as an actuary. Am I /sci/ approved smart now?
 >> Anonymous Mon Oct 26 17:42:00 2020 No.12276458 >>12276445You 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.
 >> Anonymous Mon Oct 26 17:54:56 2020 No.12276503 >>12276458>t. reddit undergrad
 >> Anonymous Mon Oct 26 18:12:25 2020 No.12276585 File: 188 KB, 1439x859, Screenshot_20201026-170941_Firefox.jpg [View same] [iqdb] [saucenao] [google] [report] >>12276445this? youre probably smarter than most people, but youre not really "smart" smart.congratulations, though
 >> Anonymous Mon Oct 26 18:16:40 2020 No.12276609 >>12276445Nope, just 10% more kike than beforeIf you keep at it you might even be allowed into israel
 >> Anonymous Mon Oct 26 18:33:17 2020 No.12276685 File: 176 KB, 868x1228, __ibuki_suika_touhou_drawn_by_uu_uu_zan__0b7d88ff75136a373075c8ac73c83a3b.jpg [View same] [iqdb] [saucenao] [google] [report] >>12276242There is some $b \geq a$ such that $p(x) \geq cx^ 2$ for some constant $c > 0$. Proving that there is such a $b$ and such a $c$ is left as an exercise to the reader. Showing that $b$ is reached in finite time is also left as an exercise.Then, you can just compare with the differential equation $\dot{x}(t) = cx^2 (t)$, which is, by the by, a special case of your original problem.Additional hint: Throw $y' = cy^2$ in WolframAlpha.>>12276445I don't know about /sci/ approved, but I'm not approving anyone without a Remilia folder.
 >> Anonymous Mon Oct 26 18:34:20 2020 No.12276688 >>12276685*such that $p(x) \geq cx^2$ whenever $x \geq b$.
 >> Anonymous Mon Oct 26 18:37:15 2020 No.12276696 >>12276685What equation most accurately describes the stink emanating from those 2hu armpits?
 >> Anonymous Mon Oct 26 18:44:03 2020 No.12276719 What sorts of job opportunities will I have if I get a PhD in nuclear engineering?
 >> Anonymous Mon Oct 26 18:48:58 2020 No.12276734 Classical mechanics books for undergrads?
 >> Anonymous Mon Oct 26 19:16:10 2020 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!
 >> Anonymous Mon Oct 26 19:24:07 2020 No.12276819 >>12276696The constant zero function.
 >> Anonymous Mon Oct 26 19:33:18 2020 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?
 >> Anonymous Mon Oct 26 19:35:29 2020 No.12276847 >>12276844you 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
 >> Anonymous Mon Oct 26 19:43:06 2020 No.12276860 File: 221 KB, 996x1186, p1.png [View same] [iqdb] [saucenao] [google] [report] 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 $x+iy$ and you can also represent it with $re^i\theta$ and cover the same space.so why would these two surfaces be so different for what is essentially the same mapping?
 >> Anonymous Mon Oct 26 19:44:28 2020 No.12276870 >>12276847>le hospitalhaha>you have to do bothOkay 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.
 >> Anonymous Mon Oct 26 19:45:17 2020 No.12276871 >>12276847You can also apply it if it's $\frac{0}{0}$.
 >> Anonymous Mon Oct 26 19:50:24 2020 No.12276885 >>12276860Quite possibly the single dumbest question I've ever seen here.
 >> Anonymous Mon Oct 26 20:00:26 2020 No.12276914 >>12276885But why though?
 >> Anonymous Mon Oct 26 20:08:14 2020 No.12276938 >>12276914Do you think Wolfram can tell that r stands for radius and theta stands for angle? It's just assuming they're normal variables.
 >> Anonymous Mon Oct 26 20:13:33 2020 No.12276953 >>12276938how do i tell wolfram that r stands for radius and theta stands for anglehas anyone informed mr wolfram of this terrible error
 >> Anonymous Mon Oct 26 20:15:08 2020 No.12276956 >>12276938>Do you think Wolfram can tell that r stands for radius and theta stands for angle?Yes.
 >> Anonymous Mon Oct 26 20:24:49 2020 No.12276985 >>12276953Ask for a polar plot.
 >> Anonymous Mon Oct 26 20:27:50 2020 No.12276992 >>12276985ah thank you
 >> Anonymous Mon Oct 26 20:41:12 2020 No.12277039 >>12276331makes sense. Thanks anon
 >> Anonymous Mon Oct 26 21:00:33 2020 No.12277101 >>12276860God damn it that's funny. Thank you for the laugh anon.
 >> Anonymous Mon Oct 26 21:05:02 2020 No.12277109 >>12276734Kleppner & Kolenkow was good, has tough problems. Maybe not so good if you didn't do well in high school physics.
 >> Anonymous Mon Oct 26 21:10:19 2020 No.12277122 >>12277101Cheers, lad.
 >> Anonymous Mon Oct 26 21:28:27 2020 No.12277170 File: 344 KB, 1024x923, 1603749795052~3.jpg [View same] [iqdb] [saucenao] [google] [report] Do I have Autism?
 >> Anonymous Mon Oct 26 22:07:13 2020 No.12277294 >>12276734taylor mechanics is the only book you need. about a 2nd/3rd year undergrad level
 >> Anonymous Mon Oct 26 22:15:08 2020 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"
 >> Anonymous Mon Oct 26 22:17:20 2020 No.12277316 >>12277311read 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
 >> Anonymous Mon Oct 26 22:19:10 2020 No.12277318 >>12277316That is something interesting I had not thought about. thank you for this advice.
 >> Anonymous Mon Oct 26 22:32:42 2020 No.12277354 File: 27 KB, 112x112, pepe_leaving_gif_apu_apustaja_never_come_back.gif [View same] [iqdb] [saucenao] [google] [report] 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
 >> Anonymous Mon Oct 26 22:47:39 2020 No.12277387 >>12277354Honestly, 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.
 >> Anonymous Mon Oct 26 22:49:48 2020 No.12277390 >>12277354Learn a language or instrument.
 >> Anonymous Mon Oct 26 23:42:39 2020 No.12277504 >>12265984I 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.
 >> Anonymous Tue Oct 27 01:42:39 2020 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.
 >> Anonymous Tue Oct 27 02:12:05 2020 No.12277799 File: 113 KB, 1200x1920, how-to-prove-it.jpg [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Tue Oct 27 08:54:10 2020 No.12278421 File: 30 KB, 631x368, bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.png [View same] [iqdb] [saucenao] [google] [report] 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)
 >> Anonymous Tue Oct 27 09:11:41 2020 No.12278452 >>12278421It is right x^2+y^2=r^2 and not r
 >> Anonymous Tue Oct 27 09:12:55 2020 No.12278456 File: 36 KB, 494x252, fields.png [View same] [iqdb] [saucenao] [google] [report] Would the induced emf in this case be clockwise or anticlockwise?
 >> Anonymous Tue Oct 27 09:49:42 2020 No.12278539 >>12278456There 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.
 >> Anonymous Tue Oct 27 09:57:51 2020 No.12278549 >>12278539Yeah I got it wrong, first time trying to visualise 3D space with these questions and it's fucking me up..
 >> Anonymous Tue Oct 27 10:03:10 2020 No.12278559 >>12278549>He can't visualize donuts flying through a magnetic field in 3d spaceGay
 >> Anonymous Tue Oct 27 10:06:26 2020 No.12278563 >>12278559I 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.
 >> Anonymous Tue Oct 27 11:12:40 2020 No.12278741 I just want to clarifyWhen they say $\zeta(-2)$ is a trivial zero of the riemann zeta fn, does that literally mean $\zeta(-2)=0$?
 >> Anonymous Tue Oct 27 11:27:41 2020 No.12278785 If I have $P(A|B)$ and $P(A^c|B^c)$, how would I go about finding $P(A)$ and $P(B)$?
 >> Anonymous Tue Oct 27 11:35:58 2020 No.12278814 >>12277170Nah, just low intelligence for not understanding directions
 >> Anonymous Tue Oct 27 11:46:20 2020 No.12278849 $\lnot{X}\iff{Y}$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?
 >> Anonymous Tue Oct 27 11:56:03 2020 No.12278874 >>12278785That's not enough information to determine P(B), and in most cases not enough to determine P(A).
 >> Anonymous Tue Oct 27 12:14:17 2020 No.12278946 >>12278874hmmm I see, then what about $P(B|A^c)$?
 >> Anonymous Tue Oct 27 12:25:06 2020 No.12278968 >>12278741Yes.
 >> Anonymous Tue Oct 27 12:55:27 2020 No.12279081 Analysis time.Prove that if set $A$ is compact and nonempty, then $\sup(A)$ and $\inf(A)$ both exist and belong to $A$.What I did:1) Since $A$ is compact, it is closed and bounded.2) Since $A$ is bounded, all its elements are bounded above and below and both $\sup(A)$ and $\inf(A)$ exist by completeness.3) Since $A$ is closed, $A^c$ is open.4) Let $b$ be an upper bound of $A$ that is not $\sup(A)$. There always exists an epsilon-neighborhood of $b$ that is contained in $A^c$ because $A^c$ is open. I have that $\sup(A)$ is the only upper bound that has no epsilon neighborhood contained in $A^c$. Therefore $\sup(A) \notin A^c$ then $\sup(A) \in A$.5) Similar argument to (4) for $\inf(A)$.I feel this is clunky
 >> Anonymous Tue Oct 27 13:08:11 2020 No.12279154 File: 1.09 MB, 1278x1600, __izayoi_sakuya_touhou_drawn_by_raptor7__ae52ea61db5e6b091652eea2c035d1ed.jpg [View same] [iqdb] [saucenao] [google] [report] >>12278849Yes.>>12279081I don't recall if this result has a name proper, but for any upper bounded set $A$ and any $\epsilon > 0$, there is some $x \in A$ such that $x \geq \sup A + \epsilon$.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.)
 >> Anonymous Tue Oct 27 13:09:15 2020 No.12279159 >>12279154*$x \geq \sup A - \epsilon$
 >> Anonymous Tue Oct 27 13:11:54 2020 No.12279174 >>12279154You mean $\sup(A)-\epsilon \leq x \leq \sup(A)$. In which case I get it.
 >> Anonymous Tue Oct 27 13:16:13 2020 No.12279196 >>12278968is that not proof that $2\times\infty$, and all even multiples, equals 0?
 >> Anonymous Tue Oct 27 13:20:05 2020 No.12279220 >>12279196No.
 >> Anonymous Tue Oct 27 13:21:08 2020 No.12279225 >>12279220So it is? thank you.
 >> Anonymous Tue Oct 27 14:05:17 2020 No.12279417 File: 1.18 MB, 1000x1563, 1603818164327.png [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Tue Oct 27 14:11:57 2020 No.12279450 >>12279417Also, I want to mention that I'm fairly sure it is, in fact, new. See >>/sci/image/BMbB0T9jFtr-5FZTgb4bSA
 >> Anonymous Tue Oct 27 14:33:13 2020 No.12279530 help a retard out /sci/Consider a polygon on $p$ vertices for some prime $p$. 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 $p$ play here?
 >> Anonymous Tue Oct 27 14:45:42 2020 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] 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.
 >> Anonymous Tue Oct 27 14:46:44 2020 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
 >> Anonymous Tue Oct 27 14:48:13 2020 No.12279584 >>12279580sorry to hear that anon. you should email the professor and see if you cant work something out
 >> Anonymous Tue Oct 27 14:51:48 2020 No.12279603 >>12279584I deserve it, I will still pass the class. I've been acting like a loser this semester.
 >> Anonymous Tue Oct 27 14:52:19 2020 No.12279605 >>12279575I thought people already did the math and decided it wasn't sustainable
 >> Anonymous Tue Oct 27 14:56:06 2020 No.12279618 >>12279605Well 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.
 >> Anonymous Tue Oct 27 15:12:38 2020 No.12279690 >>12278785>>12278946any statsfags here who can help a retard?
 >> Anonymous Tue Oct 27 15:32:20 2020 No.12279750 Is my laptop some kind of model of the universal Turing machine?
 >> Anonymous Tue Oct 27 15:47:58 2020 No.12279787 >>12278785$P(A)=P(A|B^c)P(B^c)+P(A|B)P(B)$$P(A)=(1-P(A^c|B^c))P(B^c)+P(A|B)P(B)$Not sure if this is correct
 >> Anonymous Tue Oct 27 15:53:32 2020 No.12279809 >>12279787You are correct but that only gives $P(A)$ as a function of $P(B)$. Sadly, to fully solve the problem one would also need the conditional information $P(B \vert A)$ and $P(B \vert A^c)$
 >> Anonymous Tue Oct 27 16:13:23 2020 No.12279858 >>12279809could I find >>12278946 with only knowing >>12278785?
 >> Anonymous Tue Oct 27 16:20:29 2020 No.12279875 >>12279858Only with all four quantities, i.e. $P(A), P(B), P(A \vert B),$ and $P(A^c \vert B^c)$.
 >> Anonymous Tue Oct 27 16:23:11 2020 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...
 >> Anonymous Tue Oct 27 16:42:46 2020 No.12279938 File: 2.80 MB, 3277x4096, __saigyouji_yuyuko_touhou_drawn_by_gominami__21d34f15064d397ab8bd1e18fc2978bf.jpg [View same] [iqdb] [saucenao] [google] [report] >>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 $p$ is odd.Your professor could be intending for you guys to exploit Lagrange, tho.
 >> Anonymous Tue Oct 27 16:53:00 2020 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.
 >> Anonymous Tue Oct 27 17:31:35 2020 No.12280071 File: 90 KB, 1051x922, bros.png [View same] [iqdb] [saucenao] [google] [report] Bros, what type of math is this and how do I learn it
 >> Anonymous Tue Oct 27 17:34:20 2020 No.12280078 >>12280071calc III + linear algebra + advanced classical mechanics
 >> Anonymous Tue Oct 27 18:12:11 2020 No.12280184 >>12280078Only done calc 2, basic matrices and vectors, and basic mechanics. How long will it take to get my math knowledge there?
 >> Anonymous Tue Oct 27 18:16:02 2020 No.12280197 I know what cos and sin do but idk where to apply them
 >> Anonymous Tue Oct 27 18:23:09 2020 No.12280229 >>12280197Pretty much any place where (right) triangles are involved.
 >> Anonymous Tue Oct 27 18:25:10 2020 No.12280235 >>12280229If i shoot a bullet and it curves downwards over time, where is the right triangle in that?
 >> Anonymous Tue Oct 27 18:32:04 2020 No.12280273 >>12279417Meds status : Not taken
 >> eng retard Tue Oct 27 18:32:10 2020 No.12280276 File: 69 KB, 692x1024, 1593595056028.jpg [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Tue Oct 27 19:27:41 2020 No.12280466 >>12280276Wild guessing and random intuition. You can also try to predict how to make terms cancel out in your head.There are really no rules.
 >> Anonymous Tue Oct 27 19:57:02 2020 No.12280542 >>12280235the initial angle that you fired the bullet can be used to construct a right trianglefrom this triangle, you use sin and cos to get the horizontal and vertical components of the velocityyou use the vertical velocity, along with kinematics equations, to calculate when the bullet will come back to the ground
 >> Anonymous Tue Oct 27 19:58:22 2020 No.12280546 >>12280184time? it purely depends on your dedicationyou 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
 >> Anonymous Tue Oct 27 20:32:05 2020 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?
 >> eng retard Tue Oct 27 20:35:29 2020 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?
 >> Anonymous Tue Oct 27 20:36:41 2020 No.12280662 >>12280643these 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.
 >> Anonymous Tue Oct 27 20:42:43 2020 No.12280683 >>12280662What about trucks, tanks, ships? Is there anywhere else other than short range vehicles that renewable would be viable?
 >> Anonymous Tue Oct 27 20:43:52 2020 No.12280687   File: 85 KB, 500x350, Mitochondria.png [View same] [iqdb] [saucenao] [google] [report] >In instances of interbreeding among identical species, the father's mitochondrial DNAentered the egg via his sperm, but after a certain amount of time, it died out, presumablyneutralized by the placenta. In other words, the father's mitochondrial DNA was ultimatelynot inherited by the birthed child. However, when different species were crossbred, theopposite was true. The offspring's mitochondrial DNA was found to be 56% paternal.Is this true?
 >> Anonymous Tue Oct 27 20:45:16 2020 No.12280692 File: 85 KB, 500x350, Mitochondria.png [View same] [iqdb] [saucenao] [google] [report] >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?
 >> Anonymous Tue Oct 27 21:10:20 2020 No.12280802 >>12278814But I didn't cross a single line.
 >> Anonymous Tue Oct 27 22:20:05 2020 No.12281035
 >> Anonymous Tue Oct 27 23:06:22 2020 No.12281151 >>12280643transition from oil is totally inevitable. it will hapen slowly over the next half century, probably.
 >> Anonymous Tue Oct 27 23:09:29 2020 No.12281160 Let $f: {\mathbb Z}^2 \to {\mathbb Z}^2$ where $f(x,y) = (28x + 38y,12x+16y)$. What is the index of $\text{Im } f$?
 >> Anonymous Tue Oct 27 23:17:02 2020 No.12281183 >>12280643>>12280683The 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
 >> Anonymous Tue Oct 27 23:37:13 2020 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] 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?
 >> Anonymous Tue Oct 27 23:42:02 2020 No.12281226 >>12281217sounds similar to vector graphics
 >> Anonymous Tue Oct 27 23:48:36 2020 No.12281238 >>12281217Tl;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.
 >> Anonymous Wed Oct 28 00:34:24 2020 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>efficientSeems 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.
 >> Anonymous Wed Oct 28 04:25:06 2020 No.12281630 >>12280643Any 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.
 >> Anonymous Wed Oct 28 05:42:10 2020 No.12281729 >>12281183>gas turbine or piston engine will need redesign/significant modificationSo it's already pretty complicated since most of the world runs on those, doesn't it.>>12281151>next half centurythat'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 enginesDoes 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 nuclearlmao 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.
 >> Anonymous Wed Oct 28 07:14:20 2020 No.12281849 >>12269718>>12270710>>12272857>>12274057tl:dr need feedback on my Ising model presentation, thanks lain chan / lambda / res/9558.html#19751
 >> Anonymous Wed Oct 28 07:23:06 2020 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.
 >> Anonymous Wed Oct 28 08:47:27 2020 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.
 >> Anonymous Wed Oct 28 10:15:55 2020 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?
 >> Anonymous Wed Oct 28 10:38:08 2020 No.12282238 >>12282012I 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.
 >> Anonymous Wed Oct 28 10:39:04 2020 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
 >> Anonymous Wed Oct 28 10:39:43 2020 No.12282243
 >> Anonymous Wed Oct 28 11:09:49 2020 No.12282300 File: 288 KB, 824x643, 1603897089.png [View same] [iqdb] [saucenao] [google] [report] 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 $\sqrt(a^2 \cdot b^2)$ 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:$\begin{bmatrix}\sigma^2 & \sqrt{corr} \cdot \sigma^2\\ \sqrt{corr} \cdot \sigma^2 & \sigma^2\end{bmatrix}$Now my question is: Why does this work?Why does the factor $\sqrt{corr}$ for the covariance of the normal distribution result in a correlation coefficient of $corr$ 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
 >> Anonymous Wed Oct 28 11:14:35 2020 No.12282310 >>12282300>you just do $\sqrt(a^2 \cdot b^2)$ on themI meant $\sqrt{a^2 + b^2}$
 >> Anonymous Wed Oct 28 11:42:39 2020 No.12282376 Consider the linear map$\mathbb{R}^{m\times n} \to \mathbb{R}^{m \times l}: W \mapsto WB$, where $B \in \mathbb{R}^{n \times l}$Is its transpose $\mathbb{R}^{m \times l} \to \mathbb{R}^{m\times n}: K \mapsto KB^\top$?Similarly for$\mathbb{R}^{n\times l} \to \mathbb{R}^{m \times l}: V \mapsto AV$, where $A \in \mathbb{R}^{m \times n}$.Is its transpose $\mathbb{R}^{m \times l} \to \mathbb{R}^{n\times l}: H \mapsto A^\top H$?
 >> Anonymous Wed Oct 28 11:52:40 2020 No.12282413 >>12282376It 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.
 >> Anonymous Wed Oct 28 12:07:34 2020 No.12282467 >>12282413I know jackshit category theory though.
 >> Anonymous Wed Oct 28 12:17:59 2020 No.12282501 >VerbitskyIs this guy serious?
 >> Anonymous Wed Oct 28 12:30:17 2020 No.12282532 File: 168 KB, 1535x1654, __patchouli_knowledge_touhou_drawn_by_denaseey__a458dde29ff208639757f7d77c31fd62.jpg [View same] [iqdb] [saucenao] [google] [report] >>12282376Yeah, almost. You take the base for $\mathbb{R}^{m \times n}$ to be the $E_{i, j}$ matrices (has a one in line i, row j, zero everywhere else), and order them the normal way to get the $\mathbb{R}^ {m \times n} \rightarrow \mathbb{R}^{m \times l}$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 $A \cdot B = tr(A^T B)$, so we compute the transpose of $W \rightarrow WB$ by $WB \cdot K = tr((WB)^T K)= tr(B^T W^T K) = tr(B^T (W^T K))= B \cdot W^TK$
 >> Anonymous Wed Oct 28 12:32:26 2020 No.12282539 >>12282376I 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_flatl*n x 1 |--> lm x ln times l*nThe transpose of that isW_flat |--> diag(A', ..., A') W_flatlm x 1 |--> ln x lm times lm x 1Where W_flat corresponds to W:=[W(1), ... W(m)]So the mapping is equivalent toW |--> A'W, just as it was hypothesized
 >> Anonymous Wed Oct 28 12:33:21 2020 No.12282542 >>12282532do you take any stims or are you actually this autistic about math?
 >> Anonymous Wed Oct 28 12:38:58 2020 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] >>12282542>taking stimulantsAlso, 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.
 >> Anonymous Wed Oct 28 12:40:36 2020 No.12282563 >>12282532oh wow that's pretty neatthanks! >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?
 >> Anonymous Wed Oct 28 12:41:28 2020 No.12282566 >>12282559I was asking in general, how do you not get sick of doing math?
 >> Anonymous Wed Oct 28 12:48:13 2020 No.12282598 >>12282539>W:=[W(1), ... W(m)]should be W:=[W(1), ... W(l)]
 >> Anonymous Wed Oct 28 12:49:57 2020 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 $M_{m, n}$ of m, n matrices, and it has the Frobenius inner product. By ordering the $E_{i, j}$ base, we get an isomorphism $M_{m, n} \rightarrow R^{mn}$. If we consider $\mathbb{R}^{mn}$ to be equipped with the standard euclidean product, this map is actually orthogonal. So the transpose for $\mathbb{R}^{m, n}$ equals the euclidean adjoint for $\mathbb{R}^{m, n}$, 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.>>12282566No idea. Might get sick of it eventually.
 >> Anonymous Wed Oct 28 13:59:32 2020 No.12282774 >>12282601I 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 = = tr((WB)*K) = tr(B*W*K) = tr(W*KB*) = ==> T*(K) = KB*
 >> Anonymous Wed Oct 28 14:02:17 2020 No.12282783 >>12282774>when we flatten it afterwards.I meant >when we unflatten it afterwards Like, we flatten, then we transpose, then we unflatten.
 >> Anonymous Wed Oct 28 14:23:01 2020 No.12282839 >>12282774>RIght?That's the idea, yeah.>Btw, I think >>12282532 at the end should be:>T: W --> WB> = = tr((WB)*K) = >tr(B*W*K) = tr(W*KB*) = ==> T*(K) = KB*Yeah, big dyslexia on my part.
 >> Anonymous Wed Oct 28 14:32:44 2020 No.12282874 >>12282839Last 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?
 >> Anonymous Wed Oct 28 14:44:55 2020 No.12282898 File: 11 KB, 155x443, Screenshot_1.png [View same] [iqdb] [saucenao] [google] [report] 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?
 >> Anonymous Wed Oct 28 14:52:41 2020 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.
 >> Anonymous Wed Oct 28 15:11:20 2020 No.12283008 >>12282929I see. I was trying to figure it out in terms of dual spaces, but my mind can't handle it :PThanks a lot for the help fren!
 >> Anonymous Wed Oct 28 17:46:16 2020 No.12283602 who contributed more to math peter scholze or grothendieck ?
 >> Anonymous Wed Oct 28 18:38:52 2020 No.12283876 >>12283602Grothendieck by far.
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