/sci/ - Science & Math

First for the Maslov Index.

>>12334965
I don't like this image.

fuck I have never been so exposed by a single image before.

And I was waiting for the new thread to ask for fun books for mathlets
Fug

>>12334980
Fifth for Kahler Manifolds

>>12334980
Which site do you use to get those pics?

if X is a random vector of size n following a multivariate normal distribution (each component of X follows the normal distribution N(0,1)). How would I prove that (X'X)/n converges to a definite positive matrix ? I don't even understand how such things can converge not to the zero matrix. It makes no sense to me.

>>12334965
>maths
>formerly
Wtf is this?

>>12335057
Chuck's Feed and Seed

Would it be interesting if I had an algorithm for solving the travelling salesman problem in [math]O^{470,000}[/math] time?

>>12335068
Yes, you don't though.
https://en.wikipedia.org/wiki/Galactic_algorithm

>>12335043
Baste.
>>12335047
safebooru.donmai.us , mostly.

Is there a huge difference in the editions of Fraleigh's Abstract Algebra? Do I need to buy the most recent version?

What the hell is wrong with you faggots? Honestly

>>12335097
lots lol

>>12335067
Based and sneedpilled

>>12335097
We're mathematicians. It takes a certain kind of mind. Dumb normies wouldn't understand.

>>12335096
Why don't you take a look at the summaries of both books and see for yourself instead of asking to be spoonfeed?

Are they required to make answers as complicated as possible on StackExchange?

>>12335118
Yes. They're more hostile to newfags than we are

When you guys are studying math do you stress fap? Unironically while grinding out math problems in problems section of a textbook I need to take a break like every 30 - 60 min and have a quick coom. Over a period of studying for an entire day I can easily coom like 10+ times.

>>12334965
Hey, I'm 25 and I'm thinking of starting a math or physics degree, my dream is to become a college professor, but sometimes I feel like I'm too old, since I have no experience in this I came here to ask those who are on the academia, is there still time for me or am I really too old for this? Thanks!

>>12335141
You already got an answer in /sqt/, don't shit up the general >>12334719
>>12335131
No, what?

>>12335141
>posting anime
you never had a chance

>>12335147
I want more perspectives.

>>12335166
Is "perspectives" a code word for (You)s now?

>>12335173
No, it isn't.

>>12335123
based

I do not like this thread.

>>12335226
Mean ether

>>12335056
It does not converge to the zero matrix. You have to look up the concepts of convergence in measure, convergence in probability, convergence in distribution, convergence of estimators of population moments. Mind that sequences of samples do not behave like sequences in real analysis. Here we're talking about probability.

>>12334965
yehh, uhh uh, oh GOD IM GONNA UHHH, IM GONNA NOT READ, AHHHHGG, OH GOD IM NOT READINNNNNG AHHHHHHHHHHHH

>>12334965
Why do people buy new books if they can easily find used books it’s dumb as fuck. You can get used books for like 5$.

>>12334965
>book folder up to 1GB
yup, this is me

>>12335362
I like the smell

I am a compsci grad with a minor in applied math but I cant solve integrals if my life depended for it.
I have to practise it more.

How do I find fun in solving hard integrals?

>>12335414
here you go.

>>12335414
solving integrals is a party trick for young undergrads. don't bother with it. though this book >>12335423 is kind of neat regardless.

>>12335403
>not tens of GBs
pfft

>>12335131
I fap while trying to solve a tricky problem or trying to understand something complicated.
I usuallly don't get to the point of cooming, though.
Sometimes I do what you said, but it's rare.

>>12335405
Books are like panties - best smelled used.

>>12335454
Can I have your panties bro

>>12334965
How the fuck did you niggers settle on "Book Coomer" instead of "Booker" ? baka

>>12335456
B-bro, for you, of course, I'd be honored. Could I have some of yours too? N-no homo of course.

>>12335464
It's a long story

>numerical linear algebra
literally why

>>12335587
it's like knitting a sweater but for autists

I'm sorry if this is the wrong thread, but I'm a desperate, clueless idiot who needs help with their homework:

given: training data set with 2 different labels
task 1: apply batch stochastic gradient descent and calculate the "weight vector" theta.
task 2 (what I'm struggling with): plot a separating plane between the data points given.

I have this vector theta but I'm not sure what exactly it predicts in the context of logistic regression or how to derive the plane from it.

Most grateful for any hints in the right direction.

>>12335429
shut the fuck up you fucking faggot brainlet nigger. solving integrals is the most g loaded and impressive feat an analyst can perform barring solving nonlinear differential equations. i would literally brain you with an iron rod if you said this to me irl you fucking rat algebraist retard.

>>12335666
no it's not.
be quiet.

What else are you guys into other than maths?

>>12335682

im a raging homosexual and sex offender

>>12335682
programming and (soon) theoretical computer science.

>>12335659
Your weight vector theta should describe an affine hyperplane, which can be used as a separator between your two categories of points.

Eg: you have two features (x and y axes), and you've obtained that theta0 = 1, theta1 = -3 and theta2 = 7, then you need to draw the line defined by the cartesian equation 1 - 3x + 7y = 0. If this doesn't make sense to you, check Andrew Ng's course on ML, and his episode(s) on logistic regression.

>>12335693
>>12335701
samefag

>>12335724
whats wrong with this board hating computer science? U guys call them gay but im not gay. I only dressed up as a girl a couple times and sucked off my friend in the bathroom but that doesnt make me gay ok? I just liked how it smelled and tasted and i liked the feeling of being a girl im not gay guys computer science is not gay

>>12335724
if you can't appreciate what CS has to offer, you truly are a brainlet.

>>12335701
what are your plans for getting a job? that's what I've been worried about.
are you going to grad school?

>>12335760
probably something computer related.

>>12335716
thank you for the reply!

in my scenario, there are 3 features x,y,z, and the weight vector has actually 4 values (1 was added for the multiplications, and I think the intercept - I forgot the actual explanation).

So, I'm struggling with transferring on how to take these 3/4 inputs and get my z's.

Is it possible that the plane is just defined by z = theta0*x + theta1*y + theta3 and I leave the theta2 out?

will check out your recommendation!

>>12335735
L O N D O N

>>12335763
kek okay, anon.

>>12335774
you don't seem satisfied with my answer.

>>12335666
Reported for violence and hate speech

>>12335798
N

>>12335790
Maybe it was the way I worded my question.

How do you plan on getting a job and showing employers your capable as a math major and not CS?
Also, are you going to grad school? In grad school?

And sorry for asking this here but /adv/ never replies and making a thread gets a ban or warning because it's off topic...

>>12335802
I

>>12335805
C

>>12335769
If you have 3 features, each data point is defined by a vector inside a 3D vector space. Your number of columns on your Excel spreadsheet / numpy array, etc, is the number of dimensions.
Each point can then be represented as a shape that stands for its category. Say triangles for points which resolve to category A and circles for points that resolve to category B.

Your separating space between your cloud of triangles and your cloud of circles is always an affine hyperplane. Hyperplanes in 3D are just simple 2D planes (hyperplanes are spaces of dimension n-1 in a space of dimension n). The cartesian equation for a 2D affine plane in 3D space is "t0 + t1 * x + t2 * y + t3 * z". Affine means "not passing by the origin", and that's your t0 constant term that allows this fact.

Download Geogebra and play around with cartesian equations in R2 and R3. Reading your response and seeing your confusion, I think you'll need it.

>>12335806
E

>>12335811
N

>>12335820
E

>>12335826
C

>>12335829
R

>>12335803
i don't want to work in theoretical cs, it's just a hobby. there's many directions to go with programming. don't know if studying math will make me more employable, but it's given me a good skill set to work with.
i'm not going to grad school. i don't have the patcience nor the fidelity to the institution of academia required. i'll probably continue learning at my own pace afterwards.

>>12335833
E

>>12335836
E

>>12335845
D

S

>>12335857
N

>>12335802
>>12335805
>>12335806
>>12335811
>>12335820
>>12335826
>>12335829
>>12335833
>>12335836
>>12335845
>>12335848
>>12335857
>>12335863

"NICENEGCREEDSN"

>>12335877
where did the G come from?

>>12335808
Thanks, I think I have the hyperplane part right now (I hope), but likely something is wrong with the algorithm/my theta, as the plane doesn't separate the data points, so I thought I was doing something wrong here.

>>12335902
If you implemented logistic regression on your own, check:
- that your prediction takes into account theta0 (with a column of 1s at the left of your X data matrix, or by adding the theta0 at the end for each line of your matrix product X*theta (equivalently each coordinate of your y_pred vector))
- that your prediction X*theta does indeed call expit aka the sigmoid function (if you just copy-pasted your linear regression code like a baboon)
- that your log loss aka cross entropy function calls the correct loss value for the appropriate prediction (-log(x) or -log(1-x) for 1 or 0)
- that your gradient descent algorithm is correct, and that your log loss is indeed decreasing at each cycle/epoch
- that your hyperparameters (alpha, lambda, etc) are evolving smoothly as expected, and not fucking things up

That's off the top of my head the most common mistakes to avoid.

>>12334965
dude fuck this image, please remove it
>>12335131
yes. I sometimes find myself nonchalantly playing with myself while thinking about a problem. If the urge becomes strong enough I'll reward my progress with a busted nut, focus for another few hours or so, and if the stress remains I'll continue nutting
>>12335362
>Why do people buy new books if they can easily find used books it’s dumb as fuck
Esoteric texts are difficult to find used. If your field isn't popular, or the content of the book, there is great difficulty in finding a used text

>>12335141
do you have an undergrad?
become a top tier researcher? too late.
that means top universities are closed off too.
if you really want it and stick with it for the next 10 years you can probably become a professor at a community college or small state school.

now some may say X person started late, or you can do whatever you want if you put intm enough effort. my response is:
1. this may have been possible in the past but academia has been careerized. everyone is in constant competition and time and energy are not on your side.
2. learning math/physics at that level require a ton of time and energy. at that age you start having to worry a bit about health and money and going to the dentist etc. all that distraction make it hard.

>>12336103
anon he's 25. Are you trolling?

>>12335141
what matters more and more for professorship applications is the academic output relative to your academic age. and you only start counting after your PhD. So, if it really is your dream, you're not too old necessarily, but you really need to get going.

>>12336120
He is actually 100% correct, and I'm 24. I am working with some younger 18,19,20 year olds who are motivated to work day and night, to get their king internships, work day and night there for a good offer etc. You need the same attitude to get to the top academically.
In your mid-twenties many people start to focus more on work-life-balance, not "wasting" your twenties. You're not as money/career obsessed anymore, as those are just proxies for sex and a good/happy life. when you'll get to know more people that work 25h per week from the beach you're less eager to work all night in the office.

>>12336133

I am actually extremely career/money obsessed now in my mid twenties and I didn't care at all until I few years ago I just spent all my time playing vidya/browsing 4chan and fapping.

Now normies are winding down and I have the rest of my life to autistically accumulate money.

>>12336192

this anon thinks that he's gonna accumulate money in academia

>>12336195

I'm not that guy I'm a soulless CS wagie.

What kind of videogames does /mg/ plays on its free time?

>>12336210
phasmophobia & Wii Fit

>>12336210
Touhou

>>12336210
Pokemon rom hacks. Been playing renegade platinum recently.

>>12336210
Fighting games, platformers

>>12336210
CS GO and minecraft

>>12336122
Yeah, thanks man, I'll start it in december and I hope I can keep focused on studying everyday and achieving good results. I know I'm too old to dream of working anywhere prestigious, but I don't mind working in a second rate uni, as long as I'm teaching high level maths and doing research of my own I'd be happy with that, but yeah, it will be a really long and difficult journey.

>>12336210
Chess, Poker, TF2, Melee, Q3 CPMA

>>12336391
>Q3 CPMA
>Chess
High levels of based.

>>12336395
Honestly there's nothing quite like the high of outplaying a man, knowing that you have crushed him and that you are objectively better than him.

>>12336133
Imagine losing your drive to settle for boomer balances at 24 lmao you people will get rekt easy

>>12336210
For me it's Merchant Prince (1994), Sid Meier's Colonization (1994) and Pharaoh (1999).

>>12336403
>winning a match means I'm objectively better
something something random variables. Are you an asian high schooler?

>>12336581
Are you familiar with the game of chess?
Are you familiar with hyperbole?

>>12336658
fuck off chang ming

>>12336210
I actually beat this game on 3DS. No idea how the hell I did it. It was insanely long even for a DQ game.

I want to get into maths, where should I start?

>>12336782
You might get a lot of shit for asking this question here.

>>12336783
I know but I really want to know I dont care if I get shit, so what?

>>12336785
If you're planning on self studying and not going to university then I'd suggest learning everything they teach in High School, then choose a branch you think sounds interesting and learn the prerequisites for that.

>>12336782
What do you already know? Did you take Calculus or are did you do math in high school but have since forgotten?

>>12335739
It has nothing to offer to anyone with serious intellectual inclinations. the core of the contributions that we can expect are making brain dead tasks that have served as an impediment to large scale data driven research less painful. that is it.
>>12335674
It really is you fucking queer.

>>12336789>>12336790
I'm planning on self study, I know basic arithmetic and a little bit of high school math, but not a lot. I didn't complete highshool but I've always wanted to get into math, I dont know its always fascinated me but I've never really studied it. I would like to get into calc in the future, hopefully I would be able to though I'm a massive brainlet.

>>12336804
Okay, I'd recommend refreshing first on elementary algebra. This is extremely important and one of the reasons students struggle with any future math classes is they don't have their algebra down. You could pick up any book really (something with a lot of exercises) and just start going through that. For this I suggest:

Serge Lang Basic Mathematics
or any standard textbook on elementary algebra you can find (with solutions so you can test your understanding)

I think that's a good start. Then you should look into precalc and refresh on trigonometry. I'm not sure if you want to learn proof based mathematics or stick with more computational mathematics. I'm assuming that you would be interested in learning proofs so I'd suggest you get "Book of Proof" by Richard Hammack and do every problem in that until your eyes bleed. The boring in anything is always kind of dull but it's really important to get the basics down.

>>12336822
thanks man

>>12336210
MMORPGs.

>>12336210
chess.

sadly.
All video games are an absolute waste of time.

>>12335666
Shieeet, I always thought it was showing almost everywhere convergence of Fourier series for L^2 functions. Guess I'm a retard.

>read 10 pages of math
>absolutely exhausted
>procrastinate
>exam coming up
>study like a beast for 2 days
>pass with honors
>forget everything the day after
I'm several years into my math education and I've learned nothing, or at least very little. When my classmates refer to theorems and results of earlier courses I have no idea what they're talking about.

>>12336210
I've been getting into 100% mental Sudoku, i.e. looking at the grid and then announcing for each square the number that goes in it, without ever writing anything down.

Here's the puzzle on the Sudoku Wikipedia page, if you want to give it a try.

>>12336391
>Q3 CPMA
post demo

>>12337041
Godspeed.

>>12337041
i do the same

>>12336822
>>12336829
Book of Proof is terrible though, use Velleman's How to Prove It instead.

>>12337001
Not really, if we assume life has no objective meaning to itself then all activities should be equally evaluated as wastes of time. Videogames also, most of the times, are a way of relieving stress after a day of working, you just need moderation.

>>12336780
I'm still halfway through and already at 70 hours and still in level 24.

>>12337068
What makes them so different?

>>12336391
>>12337001
Have you tried Go instead of chess?

>>12337085
Book of Proof misses somethings that Velleman covers, mostly logic stuff, I just find Velleman a more complete book with much better exercises.

I've been going through a textbook without doing the problems. Should I start from the beginning again and only move on to the next section after solving a few of the problems?

>>12337181
>I've been going through a textbook without doing the problems
That's very bad. The exercises are as important if not more important than the rest of the text and can save you a lot of time. I used to be like you, reading books without doing the exercises and I've got to tell you that as uncomfortable it is to actually do the exercises and as tempting as it seems to just move on and learn new interesting stuff, doing the exercises will save you massive amount of time because you test what you actually understand, notice the holes in your understanding and also get better at problem solving.
>Should I start from the beginning again and only move on to the next section after solving a few of the problems?
Yes, except you should solve ALL of the problems.

>>12337181
Yeah, like the other guy said, that's a terrible thing to do, you won't really learn much, theory is important, but the exercises will provide you another vision that you can't get with the theory alone.

But I disagree with the statement
>you should solve ALL of the problems.
A lot of problems are a waste of time, I mainly refer to problems that won't provide anything meaningful that you don't already know, you'll just solve them like a robot, you need to carefully read and select which problems are worth spending time on.

>>12336829
Lang is a meme. Don't fall for it!

>>12337252
>>12337194
Just another question, how long does it take for you to finish a textbook?

>>12337347
That depends on the size of the book. I finished How to Prove It in four months.

AAAAAAAAAAAAAAAAAAH I CAN'T HANDLE ALL THIS PRESSURE ANYMORE IT'S OVER FOR ME I'LL END MYSELF NOW

>>12337181
You wanna be a researcher? If so, you need to do exercises. Research if nothing else than doing exercises that no one else have done.

Does the set [math]\{ f \mid f: A\to A \}[/math] where A is a ring under function composition?

Does the set of functions [math] \{ f\mid f: A\to A \} [\math] form a lie group under function composition? Assuming A is a ring.

Does the set of functions [math] \{ f\mid f: A\to A \} [/math] form a lie group under function composition, assuming A is a ring for the same addition and multiplication operations?

Given a martingale (M_n) in a filtration (F_n), is it generally the case that M_(n+1)-M_n is independent of F_n?
I think the answer is no but my TA used this in a proof yesterday and I'm still confused about it.

>>12337442
not even a group

>>12337448
Why?

>>12335423
>George Boros

>>12337452
let A be a ring with more than one element. a constant function doesn't have inverse

>>12335666
checked and satanpilled

>>12337001
>All video games are an absolute waste of time.
grand strategy games are based and increase your management abilities

>>12337457
What about this: [math]f(x)=k\\ f^{-1}(x)=\frac{x}{k}[/math]?

>>12337467
not an inverse

>>12336192
Opposite for me, neeted it up from 18-22 and now I'm extremely passionate hardworker study 16 hours a day and have no desire to do anything but study and work im 27

>>12337491
Did you finish college already? Where are you at now friend? PhD?

>>12337494
I finished my undergrad last year, working in finance now and studying for HSK exam, gonna try to do my phd in China

>>12337368
It's gonna be fine. Control your nerves. Maybe go for a walk or something.
>>12337252
>I mainly refer to problems that won't provide anything meaningful that you don't already know
This is stupid. Beyond high school where all the problems are essentially the same, all problems are worth solving. There are usually that many problems in a textbook. If it's actually trivial you're only going to spend 1-2 minutes on it. You might think it's trivial at first but later when doing it realize it's actually not that trivial, which will be a great learning experience. In any case, the minuscule time you save by not doing problems you deem to be a waste of time before even doing them pales in comparison to the time you could save actually properly learning the material, doing all the exercises and not leaving any gaps. Exercises are there to save you time, all of them.
>>12337347
Depends on how passionate I am about the book. Can take between a week and 3-4 months.
>>12337442
>>12337457
>>12337467
Go to /sqt/ and never post in this thread again.

>>12334965
Why is applied math so gay?

https://youtu.be/SUnAvL-ThMs

this seems like something you c9uld have done in liddle school.

>>12337519
>this seems like something you c9uld have done in liddle school.
That's literally all of math, pure math included.

>>12334965
I have something to say. Math is a god tier degree, but only if from a top uni with experience in other areas. Also most high paying math jobs can be found in banking. My brother who studied mathematics from Oxbridge is making tons now working at an investment bank in London.
If you can't find a job with a math degree, you're either shit at math or have zero background knowledge.

>>12337526
Perhaps, now all those stories about Lagrange and Sophie germain doing multivariable calculus and reading kant at 13-14 don't seem so weird. Modern Education is just inefficient.

Given an angle formed by three points in the plane with algebraic coordinates, is there some way to tell whether this is a rational angle?

>>12337534
>making tons
how much?

>>12337540
120k + bonuses in his first year

>>12337549
After taxes? You'd make 200k at fang first year with a C.S degree.

Is there a way I can learn what all of these formulas and procedures are capable of solving?

Why would I need to know how to factor with the distributive property?

>>12337556
Note the bonuses. FAANG also pays well but salaries in and around 120k pounds are not too rare among Oxbridge math grads. Career growth opportunities in finance fields are typically higher as well. You could opt for a management role after a few years

Do you guys take notes in latex or on paper?

>>12337586
On a paper because I don't know LaTeX, but as soon as I learn it (this december), I'll probably make the full transition.

>>12335067
>Chuck's Feed and Seed
Redpilled

>>12337586
Paper. I use Zim.

I do not, however, really know of anything better. Unfortunately.

Lads wtf is 10/(-4j-8) in polar

>>12337519
That's an example chosen BECAUSE it's accessible, and they gloss over a lot of the difficulties you might have in trying to actually do the analysis without a priori knowing which factors matter.

But yeah, as far as these things go, lots of math isn't "hard," and it certainly shouldn't hold the mysticism that it does (normies babbling about how WOAGH SCIENCE SO COOL)

>>12337653
x=rcosa
y=rsina
is it so hard to do the calculations?

>>12337659
i'm retarded and freaking out please help me

>>12337653
rewrite so its in the form x+iy, plot on the x/y plane. use basic trig.

it's too late i'm fucked thanks anyways guys

>>12337517
>Go to /sqt/ and never post in this thread again.
Genuinely, have sex.

>>12337653
>>12337663
f(j)=10/(-4j-8)
rcosa=10/(-4(rsina)-8)
i think...

>>12337695
>rcosa=10/(-4(rsina)-8)
oh sorry, meant to be rsina=10/(-4(rcosa)-8))

>>12337734

This might belong in /sqt/ (it's a question about Taylor series) but it's in a more advanced context of asymptotic analysis so I'm asking it here. pls forgive me bigbrains of /mg/

The prof sez we have some polynomial [eqn]p(x)=x^2+\varepsilon x - 1; \varepsilon \rightarrow 0[/eqn] and [math]\varepsilon[/math] is small. So the corresponding problem [eqn]x^2 - 1 = 0[/eqn] for [math]\varepsilon[/math] equal to 0 obviouslyl as solutions of [math]\pm 1[/math].

Now since [math]\varepsilon[/math] is small, we can expand it as a Taylor series. This is what I don't understand, exactly, or at least the notation is unfamiliar to me:

For the positive root: [eqn]x = 1 + \varepsilon x_1 + \varepsilon ^2 x_2 + ...[/eqn] So we have [math]x^2 = 1 + 2 \varepsilon x_1 + \varepsilon - 1 + [/math] some higher order terms.

None of this is so bad so far, although I find the notation unfamiliar, I at least "get it" from a computational perspective, we truncate our little Taylor expansion and anything with [math]\varepsilon ^2[/math] as a term gets shoved into "higher order terms" as we compute the relevant Taylor series for the polynomial, with the knowledge that x = 1 at some point and our ability to manipulate what is assumed to be a convergent Taylor series to reconstruct the polynomial in terms of the convergent Taylor series. (Please correct me if I'm wrong about that.)

What trips me up is he then "collects terms in [math]\varepsilon[/math], with [eqn]O(1): 1 - 1 = 0[/eqn][eqn]O( \varepsilon ): 2x_1 + 1 = 0 \rightarrow x_1 = -0.5[/eqn][eqn]O( \varepsilon ^2): x^2 = (1 + \varepsilon x_1 + \varepsilon ^2 x_2 + ... )^2 \rightarrow x_2 = -.125[/eqn]

So somehow we get a system of equations that gets us some terms [math]x_i[/math] which gets us an approximation of the solutions of our polynomial in terms of a given [math]\varepsilon[/math] and we can check these approximations against the quadratic formula and figure out how our relative error works. Right?

>>12337873
This is all leading up to stuff like method of dominant balance and higher order eigenvalue analysis (and eigenfunction stuff) so I just really want to make sure I understand it because at some point I get really lost.

>>12336801
congratulations on having no idea what you're talking about.

>>12337653
Multuply by the conjugate retard, that's always the first step. When in doubt multiply by the conjugate.

https://www.strawpoll.me/21272003

How can I wiggle my way into studying math full time without breaking the bank? Is it possible, or should I resign myself to self-study if I'm not into the idea of shelling out $$$ for a master's? Can I somehow spin the shit out of my work experience and couple that with good test scores and get into an applied department?
Background:
I did the wrong sort of math degree in undergrad (applied, very few proof-based courses).
I'm coming back to actual proof based math and really loving it (mainly Tao's Analysis because I don't have time for much more than 1 book).
I'm 24, I've been in industry for 4.5 years, mostly software and data science but also loads of non-quant work (and let's face it, day-to-day software/data science is not very thoughtful).

>>12337734
Congratulations, you discovered that the real numbers are an abelian ring

>>12337916
Learn on your own, get into contact with people in the field with well-formatted questions and observations, (don't just blow their email up with your disproof of the riemann hypothesis or some shit), and get to a point where you can write a paper. Publish, check for scholarships, and repeat.

>>12337916
work experience and a background outside of pure math won’t do anything at all to get you into academia. you have literally no skills that an applied math department would care about.

/mg/ recommended books for algorithms?

Apparently twitter can't answer this equation:
6 ÷ 2 (1+2)

Some say it's 9 and some say it's 1.

>>12338057
People who write mathematics linearly should be shot. This isn't a question of skill at all.

>>12338057
Yet another example of why postfix notation is always superior.
"6 2 / 1 2 + *" has no semantic ambiguity and is much easier to read.

>>12338100
I would hate to express, say, associativity with such notation. Compare
[math]a \cdot (b \cdot c) = (a \cdot b) \cdot c[/math]
[math]b\ c \cdot a\ \cdot = a\ b\ \cdot c\ \cdot[/math]

>>12338100
Would be horrible in handwriting

>>12338050
CLRS is not only the greatest algorithm book, but also one of the greatest technical books ever written.

>>12334965
>Mfw want to get mathematics major after i finish trade school in web development
>Afraid of wasting a lot of years for nothing and still working as web developer
what do lads,this shit has been fucking my brains forever

>>12337041
Holy shit youre me

>>12337873
>>12337875
So I'm not wrong here, and it works for this example, but as per

>https://abesenyei.web.elte.hu/publications/borel.pdf

there are counterexamples for this approach. This is a "mathematical methods in physics" course, so I imagine he's not intending to give us funny counterexamples to the idea that there's some kind of nontrivial radius of convergence around the given values but I am glad that at least my pure math pedantry was not misplaced

>>12338196
Thanks my guy

>>12338143
That's wrong tho.

>>12338251
Just fucking do it, fuck society, fuck conformism, if it works it works, if it doesn't, it doesn't but it's better than living with the regret of never trying.

>>12336579
> Pharaoah (1999)
When you're a jobless Husserl scholar who works at a Wendy's

>>12338329
I guess that's what im gonna do,what is best field in mathematics that has biggest field of employment? im thinking about statistics/data

>>12338392
Research in statistics is dead, data is computer science. Algebraic Geometry and Algebraic Topology are currently the trending fields, Dynamical Systems is very huge in some countries as well, don't do anything related to foundations or number theory if you want a research job.

>>12338423
Why is statistics dead?

>>12338453
No questions left to solve

>>12338467
Does that work for all countries desu? i am from georgia(country)

>>12338472
>georgia
you mean russia?

>>12338472
Not entirely sure, but I would still say it's very unlikely to spend a career doing research in statistical theory. If you're fine doing applied research or if you just want to fuck off to industry it's another matter. But if that's the case just look into what your local polytechnic school has, and be aware that what you're going to be doing won't be mathematics, but programming.

>>12338500
I think i have made my decision,looking at my local uni i've decided to go to financial mathematics and practical use of mathematical methods in economics, what are the chances that i will be serving people at mcdonalds?

>>12338510
>>>12338500
I think i have made my decision,looking at my local uni i've decided to go to financial mathematics and practical use of mathematical methods in economics, what are the chances that i will be serving people at mcdonalds?
100%.

>>12338519
Well shit,i guess it is what it is

>>12338510
You'll do well, you can stop worrying so much. You will be working at a bank or insurance company, but from looking at your posts I guess you're okay with that. If things don't go well you can still fall back on your webdev knowledge

>>12338537
Thanks,i guess it is what it is,atleast i will have web development as second option if i will fail

>>12337570
Yes, prove the formulas.

>>12338510
>>12338522
Mathematical Economy is a really good field for earning money, but oh boy is it boring, but if you really like it go on, it's still relatively unexplored.

>>12338571
I havent started it yet but i dont care if it is boring desu,ill find ways to make it tolerable

>>12334965
This is literally me. I hate myself.

[math]\bullet[/math]What textbooks, papers or text did you read today?
[math]\bullet[/math]What non-textbooks did you read today?
[math]\bullet[/math]Did you write something today?
[math]\bullet[/math]Did you do some programming today?
[math]\bullet[/math]Did you build something today?
[math]\bullet[/math]Did you clean up something today?
[math]\bullet[/math]Did you plan something today?
[math]\bullet[/math]Did you manage to work off some bureaucracy/paper work today?
[math]\bullet[/math]Did you practiced any skills today? If so, which?
[math]\bullet[/math]Did you do sports/cardio/weightlifting today?
[math]\bullet[/math]What were you eating today?
[math]\bullet[/math]How much sleep did you get yesterday?

>>12337971
Thanks. I feel that the odds of me publishing anything useful or interesting as a non-gifted part-timer are extremely low, but the rest of this advice is more or less what I've been trying to do, though I have much more to learn before my questions stop being shit.
>>12337998
Yeah, I agree with you. Still, being able to implement something in C++/Julia/Python and having an applied math background must at least place me in some sort of bare minimum box that I can try to climb out of by putting in a lot of work...but maybe part of that work is shelling out $$$ for the master's. Thanks for the honesty.

>>12334965
>Takes countless pictures of his bookshelf for his friends
>His only friends are his books

>>12334980
I want to emphasize that this random shitpost is not only the most advanced math posted in this thread until now, it is that by a very large margin until this >>12335043 other random shitpost, followed by this >>12335323 disguised homework question.

Is there a coordinate system that, relative to Euclidean space, is in terms of tangent/secant?
Am I deranged?

why the 2 x 4?

>>12338647
>What textbooks, papers or text did you read today?
None.
>∙∙What non-textbooks did you read today?
None.
>∙∙Did you write something today?
No.
>∙∙Did you do some programming today?
No, but I played Infinifactory.
>∙∙Did you build something today?
No.
>∙∙Did you clean up something today?
No. Three days using the same clothes.
>∙∙Did you plan something today?
My suicide letter.
>∙∙Did you manage to work off some bureaucracy/paper work today?
No.
>∙∙Did you practiced any skills today? If so, which?
No.
>∙∙Did you do sports/cardio/weightlifting today?
No.
>∙∙What were you eating today?
Chips, chocolate, fried chicken and french fries.
>∙∙How much sleep did you get yesterday?
4h I guess?

>>12338774
To better show how you're simplifying all that shit?

WTF do you do with optimization? LInear programming just seems so dumb

>>12338979
You spare a few lines of code to write some inside joke that only other programmers will see

How long does it take you guys to finish a page in a textbook? I'm seeing some people say it takes them an hour.

>>12339067
Depends on the book but an hour seems excessive. Maybe at most 30mins for a single page and that seems like a lot to me.

>>12339067
Yeah, I agree with this guy >>12339075, sometimes there is some book that is really hard and I need to read the same page several times, but an hour is really excessive.

Hey guys, my lecturer is going over logarithmic differentiation right now, but something confuses me.

Say I have:
[eqn] y = ln(x^3)[/eqn]

Then its derivative is the derivative of x^3/x^3, right?

So then, why is its value [eqn] dy/dx = 3/x^3 [/eqn] and not [eqn] dy/dx = 3x^2/x^3 [/eqn]?

>>12339105
chainrule
3x^2 /x^3 = 3/x is correct

>>12339105
nah ur right
cancel ur x's, this is a 'nice' singularity

>>12339105
https://www.wolframalpha.com/input/?i=differentiate+log+%28x%5E+3%29

>>12339131
>>12339178
But wouldn't dividing by x just give you 3x/x^2?

>>12339067
Depends on what textbook. Lower level book like a linear algebra or calculus text? An hour seems reasonable. Something like a graduate level algebra text can take hours depending on the content.

>>12339067
An hour is a bit ridiculous. Honestly, it depends on the topic and how dense it is. For example, electronic circuit theory could take 6-7 minutes, but calculus could take 15-20.

>>12339358
It's definitely contextual. A whole semester covers maybe half of Rudin and that's only like 170 pages of content.

>>12337534
>tfw shit at math

F = 50lb. Is the magnitude of the resultant force not 63.4lb? mastering is telling me that I rounded incorrectly.

>>12339409
shit i think this is the wrong thread but whatever...

>>12339409
nvm i got it figured out. fuck mastering and fuck its sig figs

Are there any important classes of operators on a separable Hilbert space to which the invariant subspace problem is still unsolved?

>>12338100
>much easier to read
For an automaton, sure.

Guys, help me out I am a fucking retard. I stopped doing school work in the 5th grade, but now I'm trying to actually move into some career I'm mid twenties and I got to move out the warehouse before the robots replace me in the next 10 years. I don't "get" math. Some of it makes sense as I can envision it in the real world, but others I can't grasp at all. It seems to be almost made up and we just agree it works and it irks me. Also I'm doing Algebra 1 on khanacademy, but should I just go on to Geometry so I can move into Algebra 2? I want to ace the CLEP so any typs. Also thanks for reading my blog.

>>12339821
make sure you understand order of operations, fractions and operations between fractions, and your multiplication tables.
You may feel that it's a waste of time now, but you will be grateful later for mastering the basics.

>>12339821
>It seems to be almost made up and we just agree it works and it irks me
think you need to fire up an analysis textbook

>>12339715
it's true for normal operators so maybe we could ask about hyponormal/subnormal/paranormal

>>12337539

Different version of the same question:

The sine and cosine of a rational angle are always algebraic numbers, but a non-rational angle may have algebraic sine and cosine as well.

Given the sine and cosine of some angle, if we know that these are algebraic, and we know what polynomials they are the roots of, can we somehow tell whether the angle was rational or not?

To clarify, a rational angle would be something like three fifths of a full circle -- any angle that's rational when expressed in degrees.

>>12337539
>>12340190
Let [math]z = \cos \alpha + i \sin \alpha [/math], this is still an algebraic number.
If you have the minimal polynomials for [math]\cos \alpha[/math] and [math]\sin \alpha[/math], then you can also figure out the minimal polynomial of [math]z[/math].
Observe that [math]z[/math] is a root of unity iff [math]\alpha[/math] is a rational multiple of pi. So you just need to ask yourself "is the minimal polynomial for [math]z[/math] a cyclotomic polynomial".

How do we know that there are 49487365422 groups of order 1024?

>>12340375

So it looks like it should be possible then. That's cool. Thanks for the help. Got to go read some more about this stuff.

how 2 prove that I'll converge to the fixed point a in an interval (a, b) without danger of skipping it? I think if |f'(x)| < 1 in the whole interval its ok but in this case its not
sry if question is 2 retarded for /mg/

>>12340591
>sry if question is 2 retarded for /mg/
Then ask in es qyu tee lmao.

>>12340597
but they skip all questions that are not completely trivial, unless an animeposter answers it (who comes from /mg/ anyway)
I figured it out tho

Hey anons, I need some problems for students. Manipulating equations and proving some inequalities. Not too hard, something like harmonic, geometric and arithmetic mean but just for two nubmers - [math]\sqrt{ab} \leq \frac{a+b}{2}; a,b > 0[/math]

>>12340805
You can prove the case for n = 4 using some clever choices of variable in the n = 2 case. For the AM-GM inequality that is.

>>12340805
Which course, or at least for what kind of students? Math for physicists/cs/engineers/teachers or an actual math course?

>>12340895
teachers

>>12340613
>(who comes from /mg/ anyway)
False, /sqt/ has always been my main thread in this board.

>>12340896
Then I would recomment something where you can draw what's happening, like the triangle inequality. Had very good experience with these kind of exercises in a course that I one did the exercise classes for. It was however more about basic geometry, finding exercises outside of real analysis about inequalities is kind of hard. If I come up with something clever I'll post it.

>>12340919
Basic algebra like this is more or less the same for all students here, so I don't think drawing is necessary in most cases. If there is nice visual representation sure, but it is not needed

>>12337517
>Beyond high school where all the problems are essentially the same, all problems are worth solving.
Gonna need some elaboration on this one. I used to want to do all the problems at the end of sections, but I noticed diminishing returns rather quickly. E.g. "find the equilibria of the following systems" and it's 10 questions or so of different (but unenlightening) systems. Usually just do the last problems of a set, which are usually the most difficult. That and it depends heavily on the text you're reading. Baby Rudin, for example, has a lot of exciting and challenging problems. More textbook-ish books like Strogatz repeat themselves a lot as in the aforementioned example.

>>12340424
Someone wrote a program in Lisp back in 1975 that checked all magmas of order 1024, found which ones were groups, then found the isomorphism classes.

>>12341019
>all magmas of order 1024
All [math]({1024}^{1024})^{1024}[/math] magmas?

>>12341049
Yeah but they had some really big computers back then so it ran in a few years.

>>12335883
real g's stay silent

>>12337534

how does one get a job at an investment bank in london with a math bachelors

>>12339821
Fuck khan academy, and don't bother separating algebra/geometry/trigonometry. Read Precalculus by Stitz And Zeager. That single book will cover all you need to know about algebra, geometry, and trigonometry and is very worth the read. That book alone will teach you everything you need to know before starting on calculus.
Fuck "algebra 1" and "algebra 2", it's just algebra, and this book will teach it to you. It is available for free online.

>>12339067
sometimes as little as 20 seconds
sometimes 20 minutes plus go back to it again later

>>12339067
Can be a few hours, I think a lot about it

>>12335877
>NICENECREEDSN
Nice
I have faith in you again, /mg/

>>12342202
>>12342202
These are my favorite threads on 4chan

How do you make statistics fun to learn?

>>12342271
Every time you learn something new you reward yourself with 1 shitpost

>>12342292
ah okay, I've thought about doing something like this before but I am worried it will cause me to have bad habits. Like I have to be incentivized with something unproductive to do something productive ,

did anyone attend the reading group lecture? how was it? Should I join

>>12342353
group readings never work, most people always get behind

>>12342353
There were about 30 people, was fun

>>12342404
this one has been alive for months desu~

>>12342451
the thought of spending more than 30 seconds listening to one of you fucking faggots talk makes my blood boil.

>>12341926
Thanks sexy

>>12341878
nepotism

>>12342327
Just get deep into it

What music, if any, do you listen to while studying?

>>12342587
>>12342587

Made a new one cause I wont be here later and I dont want another shit one

>>12342589
Ambient, light stuff, with intricate interesting sounds. Like traditional Japanese music, or boards of canada

>>12342595
Yours is also shit.
I miss when people added pictures of mathematicians.

>>12342455
Maybe you're the faggot

>>12342598
>pictures of mathematicians
>rather than pictures of math
Why? The substance is more important than humans

>>12342595
Shit, bland. And boring

>>12342615
>boring
You might wanna get your dopamine receptors checked out. I stared for 10 minutes just into that pic, it's fascinating on its own.

>>12342589
just started listening to city pop this year, it's a god send for studying

>>12342620
>I stared for 10 minutes just into that pic, it's fascinating on its own.

>>12342637
Monkeys have a higher grey matter to white matter ratio than humans.

>>12342639
Youre a fucking bimb

I really don't understand what's wrong with you all. It's like children on diapers flinging shit at the wall and screaming just because ... It's their culture or something?

>>12342589
Math rock.

>>12342634
Recommend me some city pop or a good playlist of it on YouTube.

>>12342733
I'm just a basic bitch, but here
https://youtu.be/jZpeH_UfNiQ
https://youtu.be/kGcsJ_8KYw8

>>12342353
What did they read?

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆÆEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE

If you have a shape made of 4n tiles (without any diagonally floating pieces) how many different ways can you fill the shape with tetronimos?

>>12343598
Doesnt it depend how the 4n tiles are arranged?

CS or philosophy minor (pure math major)? I intend on going to grad school, but I've yet to decide if for pure math or for an applied theoretical field (e.g. CS, physics).
CS minor just seems so useful but just about everyone does it.

>>12343642
I mean, it's like you said: CS is more practical, but it's not gonna help you for grad school unless you want to do something relating to CS.

How much do you like philosophy? I loved it, and I wouldn't end up trading the education for anything. I ended up teaching myself the bits of a CS education I needed, and I was completely fine with that. Philosophy is almost impossible to learn well on your own. CS isn't, but do you really want to put in the time later if you need to? Does philosophy matter that much to you?

I've been interested in infinitesimal calculus. Is it worth to learn? what advantages does it have over standard calculus?

I've been interested in chronological calculus. Is it worth to learn? what advantages does it have over standard calculus?

>>12343984
>>12343997
not worth to learn
no advantages

>>12343642
>CS or philosophy minor (pure math major)?
I know a philosophy PhD that now does IT support for a living.
Make of that what you want.

Is an oxbridge maths degree worth it? Would I be surrounded by autist assholes?

New thread, properly made after reaching the bump limit.
>>12344284

>>12343642
I think it honestly depends how committed you are re: going to grad school. I finished a CS concentration during my first year and it was nice having a $200k+ starting job as a backup if other avenues didn't work out. It's in some ways the best 7-8 course investment you could make.

And I actually disagree with the other poster. Philosophy is definitely something you can study casually as a hobby, far more than a stem field actually. Maybe just take a few history of philosophy courses to get started with basic background.

>>12344292
thank you