@Nimza May I know what physical problem are you solving? Or is your problem purely mathematical?

@JayeshBadwaik environmental protection. I have to find intensity of factory in past time given current data of air pollution (from partially point, partially distributed sensor)

@JayeshBadwaik what about you?

@Nimza Ahh, interesting problem!

@Nimza Right now my problem is Artin's Algebra. ;-) As to the problem I am working on, I guess I have already told you I am in between degrees? I have done my bachelor's electronics and communication engineering and now planning to go into mathematics for grad school?

@JayeshBadwaik I didn't know it!

@Nimza Ahh, sorry then, I have said it a lot of times on the chat, I forget who knows and who doesn't ;-)

Right now studying for the entrance examinations to math grad schools.

@JayeshBadwaik Artin Algebra - is it pure mathematics?

@Nimza Yes.

@JayeshBadwaik And I've not decided yet about grad school... I don't know what I want

@Nimza You are a master's student right? By grad school, I meant both the master's and the integrate PhD programs.

@JayeshBadwaik ah, I've meant PHD. I'm specialist :) not bachelor or master

@JayeshBadwaik I hate current bachelor-master system here in Russia (it is new here). Exams take place day after day without preparation time. A lot of guys use system "copied-forgotten"

@WillHunting congratulations - again!

@WillHunting aha, say there are 6 exams. Then exams take 6 consequent days

@WillHunting never

@WillHunting ahah)

@Nimza Hmm. We had the same system. Exams on continuous days. It was basically like slots. There were eight slots A-H. Depending on which slot your course was in, you would get that day, and we had 6 subjects in a semester, so... pretty screwed up it was.

@WillHunting It's ok if you have enough motivation for each educational course!

and of course, mid terms we had twice in a day

@WillHunting Depends dude... depends.... what I have seen is on paper curriculum tells you like 10% of the quality of the courses.

@JayeshBadwaik ho.... that's not for me... I need a day with beer and girls after each exam :D

@Nimza girls??? as in plural? lucky dude. :P

@JayeshBadwaik no, it's figuratively :( the ideal!

@Nimza Hahaha. :P :P

@WillHunting Yeah, S.P. (Sergei)

@WillHunting Sad panda. :-(

@WillHunting: what does stop you from having a beer or a girl? :)

@Chris'ssister Aversion from one, perversion from the other. :P (To be taken lightly @WillHunting)

:D

@WillHunting oops, I've deleted the previous post. Yeah, Sergei Novikov is Fields medalist

@WillHunting ahh. point noted. :-)

@Nimza For me personally, exams were non-events, the brief interval where I had to stop studying on exciting stuff. Similar to the time when you have to stop working on your technical work to take care of legal issues.

@WillHunting Which Book? I think I have one volume of it, in English.

@WillHunting What about undergrad system I'm agree. Our profs say the same. But in the same time there is a real catastrophe with graduate education (PHD)... there are no funding and one have to work hardly to gain money for life

In the last period of time I've begun to think more to study Human Psychology. For instance, you may be a brilliant mathematician, physicist and so on, but if you live like Grigori Perelman then it's such a shame. The life is beautiful when you manage to enjoy it with the others.

@WillHunting Legal issues are important too. ;-)

@WillHunting stipend for PHD students is nearly 100 USD :D

@WillHunting: the point is that allows you to know yourself better and then you can know how to get rid of any possible fear that keeps you away from your dreams. It's important to be a very confident person. :P

@Nimza Even here, people say that Indian undergrad system is quite good. But I disagree somewhat. Here, profs want to teach, teach and teach. The feeling is, if this thing is useful, I need to teach the student how to do it. The students become accumulators of skills imparted by the prof. Leaves you with very less freedom.

@Nimza woot? BTW, that is the stipend in India for master's student. For PhD it is 3 times that.

@WillHunting: just read this (in case you didn't know) en.wikipedia.org/wiki/Pygmalion_effect

@WillHunting Are you referring to this?

@JayeshBadwaik for master it is 1000 roubles here, so nearly 30 USD :D

@Nimza Okay, what is a "good" income by Russian standards?

@WillHunting yeah! And I was wondering about education in more familiar conditions. Say with coffee and with more liberty in questions e.t.c.

@Nimza For example, in India, a good income on which a single child family can live decently well is around 40,000 INR per month almost equal to 800-900$.

@JayeshBadwaik: 800-900$ in hand?

@JayeshBadwaik hm... students who work from 4rd year of education now gain 2000-3000 dollars. That's 60-90 kiloroubles. I'm about programmers and specialists in bank. But they have no chance to continue education. They don't even go on lections

@WillHunting: do you live in US?

@Chris'ssister yes.

@Nimza Hmm. Not much difference from here (but still you are on a somewhat low end, may be around 2/3rd of what we receive), but then, a lot of things (like living and eating) are heavily subsidized) so its not very difficult but still, it is quite little.

@JayeshBadwaik hm :)

@Nimza Sorry, I misinterpretated, did you meant 2000$ per month?

@Nimza I just saw Average Per Capita Income of Russia is 21k$ something... For India it is 1/4 of that. So, your stipend is way screwed up!!

@JayeshBadwaik yup, average income is nearly 20 kroubles. There is some strange tendence. A lot of adults that I know (for example my parents) that have higher education gain in times little money then young. My mother gains nearly $15$ kroubles being a doctor

@JayeshBadwaik it is 500 USD

@Nimza Hmm. May be that just indicates low share of advanced technology and service industries? There was a similar situation in India some twenty years ago, when post graduates would not be preferred for the job, because it was assumed that the only reason they did their post graduation was because they could not get a good bachelor's degree from the outset or may be did not get a good job after bachelors. (Of course there are certain exceptions)

Even now (2007), the employability of postgrads from IITs is less that employability of grads as gleaned from the surveys of job placement.

@JayeshBadwaik yes!!! that's a perfect image of current situation here! So there are no motivation to do science here instead one internal motivation, that is contained in science :)

I don't like to think of money at all. My happiness has no connection to them. :)

@Chris'ssister if you have enough money to eat, to live then yes. That's why I need money

@Chris'ssister Your statement is true as long as the money you get is above a certain threshold, below that threshold, it creates problems.

@JayeshBadwaik: we are a poor in terms of money, but we can handle it and we're happy.

@Chris'ssister we can be happy, that is not the point here. But then, your expectations of yourself have to decrease proportionally. (below the threshold)

@JayeshBadwaik oh, I have to go. Will learn russian language. It's the most difficult course this year :D

@Nimza :P Learn well. :-)

Bye

bye

Bye

${}{}$

I am also going out, see you guys later.

@JayeshBadwaik: yeah. OK

I need to leave too.

bye

I am all alone here? =(

$$f(n,m) = (2n-1) \cdot 2^{m-1}$$ is a nice function.

@N3buchadnezzar Not quite!

=D

Grandpa is here.

LOL

I am surely joking

I have three days to learn this material

wiki.math.ntnu.no/tma4145/2012h/themes

Is hat function for setting up a 1-1 mapping between integers and pairs of integers (from a distant memory)

@OldJohn Indeed, that is pretty neat

Yep - I think I remember using it for exactly that purpose long ago

You used the cantor pairing function to fight of dinosaurs?

I wonder how you would create something similar for triples of integers ...

Wiki has a generalization of the formulae

@N3buchadnezzar darn

You could just not check it out, and try for yourself..

@N3buchadnezzar hmm - maybe I have more important things to do :)

Like being retired, traveling the world, and saving young virgins from their horrifying math homework.

Huh, I never heard about $\mathbb{P}$ before.

@N3buchadnezzar projective plane?

The set of all primes, strangely enough

@N3buchadnezzar Ah! - not seen it used for that, I don't think - but it is a sensible notation

Can anyone answer this question ? math.stackexchange.com/questions/247129/…

Thanks

@Chen sorry - not an area I know about

In 1882, Ferdinand von Lindemann published a proof that the number $\pi$ is transcendental. He first showed that $e$ to any nonzero algebraic power is transcendental, and since $e^{i\pi} = −1$ is algebraic (see Euler's identity), $i \pi$ and therefore $\pi$ must be transcendental.

Hmm, I do not understand this argument. See here

@N3buchadnezzar when I was at school, I tried hard to understand that proof, b ut never really managed it

So a trancedental number, raised to the power of another trancedental number is rational? ..

Ah, I get it!

@N3buchadnezzar not sure about that - I will take a look after I have eaten ...

@N3buchadnezzar It's a proof by contradiction: if $i\pi$ were algebraic then $e^{i\pi}$ would be transcendental.

@peoplepower Yeah, I just got it!

Math is cool

This chatroom is awesome, I ask these weird, strange, silly questions. And you are like: "Well thanks for asking sir. Here take this well thought of answer, and these eight relevant sources and a ice cream. "

@N3buchadnezzar Not all questions get such a kind response - some dumb ones get less welcoming responses ... so I guess you have been asking interesting ones :)

@OldJohn =)

Okay so Surjective from a set $X$ to a set $Y$, means that all elements in $Y$ lies in the range of $X$? Or that all elemets of $Y$ is being mapped to from $X$? Not quite sure how to state it..

or; "every element in Y is the image of some element in X"

Both are correct. A more formal statement might be for every $y\in Y$ there is a nonempty set $X_0\subset X$ such that $f(x_0)=y$ for each $x_0\in X_0$.

all come to the same thing really

Note that there is a (unique) surjective function from $\emptyset$ to $\emptyset$. :)

@peoplepower Cool

I tried to make the unit sphere into a vector space, that was hard ^^

later. folks

@OldJohn Bye!

@peoplepower bye

@peoplepower Defining scalar multiplication as $\lambda = 1 - e^{-\lambda^2}$ and so forth.

@WillHunting I just realized why my touchpad is not working. It is worn out! :P

Certain areas of it which I use frequently and have acquired a big shine are not working properly, but the touchpad works perfectly fine near the edges which I have not used much. Anyway, that is my theory.

@WillHunting Also, you gravatar when looked at in the thumbnail size looks like a middle finger. :P

Hi =)

@N3buchadnezzar Hi.

Soup dogs?

Naah. No soup for me. Only salad.

how do i make numbers bigger on frac

$\frac{1}{x-x-x-x}$ is kinda squished

@KaliMa use \displaystyle or \cfrac og double dollar signs

or \huge

what can i do with displaystyle

Make things not look squished..

$$ \Huge \frac{1}{x-x-x-x}$$

@KaliMa Something like this? ^^

i mean is it just displaystyle by itself

or do i need to specify some size parameter with it

@N3buchadnezzar or align environment!

@KaliMa Quote my messages to see how i wrote them.. Right click -> show math as -> tex commands

@JayeshBadwaik Does not make the fraction larger :p

I wish there were something bigger than \Huge

@N3buchadnezzar It makes it large enough for the purpose and follows the philosophy of LaTeX of using only semantic markup.

@N3buchadnezzar Hmm, I have almost never used \Huge etc in my work, however, sometimes I have used the mathrel package for bigints and bigsums etc

I want it for the comical effect

You want something large huh? I WILL GIVE YOU SOMETHING LARGE

Gives the biggest fraction the world has ever seen

@N3buchadnezzar Graham's Fractions?

how do i do integral from a to b in tex?

\int_a^b ?

\int_a^b

@OldJohn too quick for me :-)

@robjohn That is unusual for me - I am normally the slow one :)

@KaliMa do you have the MathJax bookmarklet installed?

i do

good :-) so we don't look like we are speaking in tongues

And idk the name of it

but after you integrate the integral

there's some equivalent bracket that you put on the right

with the bounds

like integral from a to b on x^2 for instance, becomes x^3/3 ]from a to b

not sure if making sense, my math jargon is weak

$\left[ x x x \right]_a^b$ maybe?

$\left \right$

what do those do?

@KaliMa not totally sure! - I am not a texspert :(

awesome though, thank you all so much

this page has a bit of explanation of \left

See you all later!

Too bad it doesn't mention \bigl, \Bigl, \biggl, etc. and \bigr, \Bigr, etc.

Hi guys

But thankfully it doesn't mention $$..$$

I am feeling bad... and i need a hug...

@Charlie MARILIA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!‌​!!!!

Hey!

@Charlie I never see you anymore

Neither do i

@Charlie Where do you hide?

:)

In my university

Can anyone here make an edit freeze on a question?

No one missed me :(??

@Charlie We all did. Look at the transcripts!!!

@JayeshBadwaik hii !!!!!!

etc. :)

@Argon: what's all that?

@robjohn Everyone missed @Charlie

@Argon Nobody misses me >8(

@robjohn, you have some powers, right? Is there anything that can be done to save this question from its author?

@robjohn Because you are around, hahaha!

@AntonioVargas what is Becky doing to it?

How cute Aaron

@Charlie ????

Ooh, I think it is better with a B... >B(

@robjohn See the edit history, particularly revisions 4 and 7. The entire content of the question is in the title, and for some reason Becky has been editing the title to remove the sum in question.

@Argon you guys missed me. thought you would't even realize...

Edit 6 changes the sum to make the answers irrelevant.

@AntonioVargas So Edit the question so that the question is in the body, then she can change the title all she wants. I'll do it.

@jay ??

@robjohn That's probably the best option. I'll do it if you don't want to.

@robjohn thanks :)

@AntonioVargas It's done

@Argon what have you been doing?

@Charlie Not much :) As always!

You?

Studying

@Charlie Bleh

@Charlie be careful what you ask, you may get an answer :-D

Sigh... :'(

@Charlie What???

Me not ok

Don not want to make any exams anymore ...

I'm sad

@Charlie I hate exams :(

Aaaa

What about your bridge?

good evening!

hello $M^2$! @Charlie

@Charlie We will see tomorrow!

@aDangerousIdea :))

@Nimza hi Alexey !!!

hi @robjohn, is there something like pseudoinverse matrix for operators? I have to find minimum of $f(Q) = \langle (\alpha I + K^{\ast} K) Q, Q \rangle + \langle h, Q \rangle $, where $Q \in \mathcal{L}^2(0,1)$ and $K$ is a compact operator. But in general $\alpha I + K^{*} K$ may not be invertible! (if $-\alpha$ is an eigenvalue of $K^{\ast}K$)

@Argon hmm

@Nimza If $f$ is injective, you should be able to invert $f$ on its range, which is what the pseudoinverse of a matrix does.

@Charlie I will tell you strength/mass

@JayeshBadwaik i like soup ...

@Nimza Other than that, I don't know of any general formula for pseudoinversion

@Argon what?

strength to mass of bridge ratio

@Argon hey Aaron, if will was here he would certainly complain about the amount of exclamation. points

@robjohn hm... and I had a particular idea here. Since $K^{\ast}K$ is compact and self-adjoint a set of eigenvalues $\alpha_n$ is discrete. So I can formally invert $\alpha I + K^{\ast}K$, find explicit formulas for minimizator $Q_{\alpha}$ and consider it as a limit of minimizators for $\alpha_{n} \to \alpha$, where $\alpha_n$ are not eigenvalues... but I don't know if such sequence of minimizers will converge to minimizer

@Nimza That sounds like a good approach. I used something like that in one of my answers.

@Nimza Not exactly the same, but similar

@robjohn thank you for link

@Nimza whether it will be of any use is questionable :-)

Hahaaha!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

@Charlie I like soup too! But right now salad...........

:-)

@Charlie!!!!

@JayeshBadwaik :D

Hi @JayeshBadwaik!

@Argon Hello!! Wassup?

@Charlie Wassup?

@JayeshBadwaik Not much, you?

@Argon Just came back from dinner. Now planning to try to study.

@JayeshBadwaik What time is it for you?

@JayeshBadwaik not much

Charles

@Argon 21:42

@JayeshBadwaik Hmmm...

@Charlie ohh, how many exams remaining?

@JayeshBadwaik three

@Charlie What subjects?

@JayeshBadwaik read my first message

@Charlie hugs

@Argon linalg stats analysis

@JayeshBadwaik thanks

@Charlie I see...

@Charlie is it raining? hot? cold?

@JayeshBadwaik both

This week is a little hot, sunny. but raining

@Charlie At least it is not cold... :)

@JayeshBadwaik what is your department? (here it is called кафедра, transliterally $\kappa \alpha \theta \varepsilon \delta \rho \alpha$ in russian, and I like this word so much)

@Charlie both of three?

This week is a little hot, sunny. but raining

@Nimza department? Electronics and Communications Engineering Department....

@Charlie ahh... nice. :-)

@JayeshBadwaik and faculty? something like applied mathematics?

@Nimza No, no. I am an engineer through and through as of now.

@JayeshBadwaik don't be afraid to mail me. i may not reply but i can read.

@Charlie okay! Which number jersey should I wear btw? ;-)

@JayeshBadwaik ah :) I'm "systems programmer" :D how do I hate it! programming in general, except scientific

@JayeshBadwaik you choose

@Charlie 10....

@Nimza ahh... systems programmer.. hmm... aren't systems programmers supposed to program systems? What are you doing analyzing all the environmental models?

Or is the programming going to come later, after the analysis?

@JayeshBadwaik that's why I asked you about department! Here there are some departments for guys who disappointed in systems programming :D we chose dept on 2-nd course, in the end. So systems programming for ME was on first two courses. Architecture, constructing of compilators, networks and other things - I really hate these things :(

@JayeshBadwaik but when I entered university I liked it so much

@Nimza I am having a little difficulty understanding you. You mean that you choose your courses in the second year?

@Nimza You loved system programming when you entered the university but now you do not like it that much?

@Nimza If my above guess is correct, I sympathize with you. :-(

@JayeshBadwaik aha! so first 2 years are general - for everybody. And from 3rd course you belongs to your personal department. There are 9 guys on mine.

@JayeshBadwaik aha

@Nimza okay. Gotcha.... :-)

@Nimza That way, if I had to say, I will say that I was in device physics and integrated circuit design.

@JayeshBadwaik As we speak I am coding an Arduino Microcontroller!

@JayeshBadwaik nice

@JayeshBadwaik yeah! integrated circuits are cute!

@Argon Cool. What are you trying to do on it?

@JayeshBadwaik Meh, nothing serious. Analog I/O, lights and stuffs.

@Nimza As long as you don't have to deal with the noise! ;-) Analog/Mixed Circuit Design.....

@JayeshBadwaik i think someone forgot to send me certain things...

@JayeshBadwaik Have you ever done something with cell phones?)))

@Charlie That someone is sorry. :-( He will act on it soon.

@Nimza nopes. I have studied most of theoretical things with it. Nothing practical.

@JayeshBadwaik hmm

@Argon hmm. I wanted to get a board for myself. Is Arduino a bare bones ARM processors, or does it have some kind of OS already present?

@JayeshBadwaik Not sure. Got it yesterday!

It uses a weird version of C

@Argon It uses C all right. It just has some ARM architecture specific functions/ assembly.

@JayeshBadwaik But a weird version. Not like PICs

void loop()

void setup()

@Argon Eh? That's unheard of? What's different? PIC is a different architecture, it will have its own set of functions needed to initialize the stuff.

@JayeshBadwaik It's a bit odd. I will have to get used to it.

It's a bit easier to use though for basic stuff...

arduino.cc/en/Tutorial/Blink

If i need help in a few exercises, anyone would help?

@Argon hmm.

@Charlie yes.

@Charlie If I can!

:)))

@Charlie sure thing

even if I can't...... eh wait....

@JayeshBadwaik :)

@Charlie Lots of mouths on that face!

:DDDDDDD

and here is my @Aura to impress you all. :D (@Aura please do not take any offence).

@Argon :-D)D)D)D)D)D)D)D)D)D)

@JayeshBadwaik :=D=D=D=D=D=D=D

Bye all, class is over!

Hahahaa!

@JayeshBadwaik i think you can

@Argon This is what happens when you do not teach programming well. :P

Also why should you start naming your dog after computer viruses

hello

$$\int \int \cdots \int $$

scary

@cassandra0 not really any more scary than an n-th derivative, maybe

@cassandra0 Why?

:D

I want to solve a math problem

@OldJohn Man.. you are faster than everyone today!! :-D

@JayeshBadwaik old - but not yet dead :)

@cassandra0 Prove that $I_n - AB$ is invertible if and only if $I_m - BA$ is invertible where $A$ is an $n\times m$ matrix and $B$ is an $m \times n$ matrix. (Do not google).

It's unlikely that I could prove that

I know this is a good problem

@cassandra0 Actually it is quite straightforward (that is what everyone says when he knows the solution). I now know one very elementary method (and somewhat difficult to strike upon) and two quite simple methods form linear algebra. :-)

:-)

@OldJohn Good!!

@JayeshBadwaik :)

archive.org is giving me speeds of 20 KB/s :-(

even it's speeds are historically accurate

@cassandra0 :D

finally torrents for the win. :-)

@robjohn Yup, sequence of minimizers in this case will be a minimizing sequence since $\alpha I + K^{\ast}K$ is strictly convex with constant $2\alpha$ and hence $\alpha \|Q_n - Q^{*} \|^2 \leq f(Q_n) - f(Q^{\ast})$

@JayeshBadwaik I prove that somewhere on site

@Nimza very nice

oh yes I think it's great that the archive.org use torrent

this is a very innovative idea