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00:00
@Hippalectryon "Obviously" is not a proof
I will retreat back to my hole now
But isn't it really obvious ?
r9m
r9m
@BalarkaSen hmm .. is this why you were asking about that $\log n$ thing the other day ?
since sqrt(1)=1
@r9m Yep.
How would you give a high level proof that the Gaussian elimination method can be directly extended to solve linear systems in any field?
00:00
And I figured it out.
r9m
r9m
@BalarkaSen :-) you made that problem ?
@r9m No
@Hippalectryon xkcd might not be a reference, SMBC undoubtedly is
@BalarkaSen щ(゚Д゚щ)
r9m
r9m
@robjohn ow !! they are supposed to be the minus signs ! :O
00:04
@r9m That is an "en-dash" –
@r9m there is my solution if you're interested. @Hippa don't click.
r9m
r9m
@robjohn :O oops .. then how do I write the minus sign ?
@r9m I don't know... I've never composed anything there.
@r9m Your other article read fine.
r9m
r9m
okay :)
@BalarkaSen He's going to click.
r9m
r9m
00:07
@BalarkaSen Nice :-)
@MikeMiller Self discipline being of a mouldy old dishrag, yes, I guess so.
@MikeMiller ಠ︵ಠ
@r9m Nothing is rendering there anymore.
r9m
r9m
@robjohn OMG ?!! :O
@r9m I'm wondering if there is another reason underlying this.
r9m
r9m
00:10
@robjohn I'm using Chrome browser .. its working fine for me .. but when I switch to firefox it doesn't work :(
@r9m I am using Firefox. I upgraded a while ago...
@r9m It says there is an update to 32.0 now.
I upgraded to 31.0 just 2 weeks ago
@r9m what version of Firefox?
r9m
r9m
@robjohn I haven't used firefox since I upgraded to 32.0 .. I have to try and see if it works now
@r9m I will upgrade.
r9m
r9m
@robjohn ya .. its working for me now on firefox :)
@MikeMiller Did you ever write up the order of automorphism group stuffs you were thinking about?
00:15
@r9m restarting now...
Okay, let me try again.
@r9m Doh! the URL you gave me to look at was https... I changed it to http and it worked
I remember there being some problem with https pages
r9m
r9m
@robjohn I see ..
@BalarkaSen No. I will, eventually.
@r9m secure pages may be more strict about what javascript they let run
r9m
r9m
@robjohn ya .. I had to click on the 'load unsafe script' in chrome ..
I'm really ignorant of these stuff .. :{
@r9m Ah. I should look for an option like that in FF
@r9m I was looking at something using about:config
we are heading out to dinner... BBL
r9m
r9m
okay :)
01:33
@r9m
@robjohn
Can you vote to undelete this?
r9m
r9m
01:58
@PedroTamaroff sorry I was afk .. shows 'voluntarily removed by its author' ... how do I vote to undelete it ?
@r9m There's a button. Can you see it?
r9m
r9m
@PedroTamaroff I don't see the button :o
@PedroTamaroff This is how it looks for me .. where is the button supposed to be ?
@r9m Oh, you don't have #supahpowaz
=)
r9m
r9m
@PedroTamaroff my reputation is too low to have any exciting supahpowaz :|
02:25
@PedroTamaroff I am hungry.
02:38
@MikeMiller I am turkey.
I don't buy it
03:26
@MikeMiller I have a prawhblem for you.
I am sure a child could do it, @PedroTamaroff
@MikeMiller Show that $\{0,1\}^{\Bbb N}$ with the product topology is compact by showing it is metrizable and then showing it is sequentially compact.
@PedroTamaroff No.
Well, I tried.
Good night.
03:29
:P
Mr @Pedro
He's long gone, @Ted
 
1 hour later…
05:08
@PedroTamaroff It was deleted by the owner. I should only undelete it if the owner asks.
@PedroTamaroff Have you voted to undelete it?
 
2 hours later…
06:55
Hi
So I have a silly question
If $f(f(c)) = c$, is $lim_{n\to \inty}f^n(c) = c$?
no: consider $f(x) = 1-x$, $c=0$
 
1 hour later…
08:02
The question titles on this site are atrocious.
Hello @IceBoy
Hi pal
How are you @WillHunting?
I am OK.
It seems that Charlie doesn't come to chat anymore. I think she has found a bf.
Perhaps.
You should try to find a gf
08:07
It seems it is not a good idea to do so before I get well.
Don't put your life on hold my friend.
Live and learn as they say.
That is why I really hope to get well by the end of 2015.
I believe in you.
But maybe finding a gf would help me get well.
That's^ what I mean.
08:10
Are you married?
You are very mysterious.
I don't trust easily.
Gotta run pal, talk to you later :-) @WillHunting
OK.
Hello @Chris'ssis
08:27
This chat is dead.
09:20
@WillHunting Greetings
I was just looking at an answer and it seems that no one noticed something important there.
$$\sum_{n=1}^{\infty}\frac{(-1)^{n-1}}{n}\left(\frac{\pi^2}{6} \quad -\sum_{k=1}^{n}\frac{1}{k^2}\,\right)=\frac{\pi^2}{4}\ln 2 -\zeta(3)$$ This is not explained at all.
It's from the Oloa's answer here - math.stackexchange.com/questions/902088/…
This step itself might be pretty challenging for many. I don't think it can be skipped like that.
Huy
Huy
@WillHunting: It most certainly isn't dead.
09:56
@robjohn @r9m I wonder if this one can be awesomely done by series manipulations only :-) $$\sum_{n=1}^{\infty} \frac{(-1)^{n+1}}{n }\left(1+\frac{1}{2^2}+\cdots +\frac{1}{n^2}\right)$$
r9m
r9m
@Chris'ssis ya I guess :-)
generating functions can kill that for sure
@r9m Did you ever do it like that? :-)
r9m
r9m
@Chris'ssis I have to try it :-)
10:00
Why so much grins and smiles?
@BalarkaSen They are pretty meaningful ... (it might emphasize the fact that it is possible to do it like that)
@Chris'ssis Superfluous.
Not to mention annoying.
=P
r9m
r9m
^_^ :) ;) :D :-) :P
10:02
le sigh
Every smiley looks way more professional when bolded. :)
I never use :-type smileys. =-types are much preferable.
r9m
r9m
hmm .. piece 'o cake
I feel like I am going to leave this degree with nice knolwedge in probability, combinatorics, graphs, discrete mathematics, logic and set theory and all that. But my analysis and calculus are just high-school level with a bit more experience. I really some good book for these two.
Rigorous yet readable
10:21
hi hi
r9m
r9m
@Chris'ssis have you seen @robjohn the wizard's solution ? :D
@r9m Which solution?
r9m
r9m
@Chris'ssis the one my last message is linked to of course
http://math.stackexchange.com/questions/922338/find-a-solution-of-u-xxu-yy-axbyc-for-given-real-constants-a-b-and
^^
@r9m Where?
10:27
sometimes I hate texmaker. I was crying like crazy earlier because I pressed save so many times and the file rolled back to only the first chapter being typed T___T!
This time I saved two copies AHHAHAHAH!
r9m
r9m
@Chris'ssis wait I am looking for the link .. as far as I can remember he did it in a few lines :-)
@r9m Ah, got that.
r9m
r9m
13
A: $\sum_{n=1}^{\infty}\frac{H_n}{n^2 2^n}=\zeta(3)-\frac{1}{2}\log(2)\zeta(2)$

robjohnWe will make frequent use of $$ \binom{n+1}{k+1}=\binom{n}{k}\frac{n+1}{k+1}\tag{1} $$ The Generalized Harmonic Numbers of the second order are defined as $$ H_n^{(2)}=\sum_{k=1}^n\frac1{k^2}\tag{2} $$ The factor of $2^{-n}$ in each term reminded me of the Euler Series Transformation. Reversing t...

@Chris'ssis :D
@r9m Yeah, that's the way.
51
Q: Proving an alternating Euler sum: $\sum_{k=1}^{\infty} \frac{(-1)^{k+1} H_k}{k} = \frac{1}{2} \zeta(2) - \frac{1}{2} \log^2 2$

Mike SpiveyLet $$A(p,q) = \sum_{k=1}^{\infty} \frac{(-1)^{k+1}H^{(p)}_k}{k^q},$$ where $H^{(p)}_n = \sum_{i=1}^n i^{-p}$, the $n$th $p$-harmonic number. The $A(p,q)$'s are known as alternating Euler sums. Can someone provide a nice proof that $$A(1,1) = \sum_{k=1}^{\infty} \frac{(-1)^{k+1} H_k}{k} =...

r9m
r9m
@Chris'ssis ah yes .. that one !! Its a goldmine of awesome techniques !!! :D
10:34
@r9m The step $(6)$ is not trivial.
:(
I don't get what the person is saying... really x.x
11:02
Can anyone tell me how to do the following *without* Stirling?
$$\lim_{n \to \infty} e^n \cdot \prod^{\infty}_{a=1}\left(a - \frac{1}{n}\right)$$
I've seen those in Discrete Math textbooks ^
@usukidoll: $\dots$ I'm a long way from reading one of those.
what math are you in?
@usukidoll: Level (-1)
11:06
@Nick yo
........
@BalarkaSen: Yo yo yo, Sensai. Got a katana blade I can slice that limit with?
texmaker can be rude.... I save with ctrl s and somehow the document was rolled back
since it was a lot of typing I wanted to bash my head against the textbook
@usukidoll: I'm in XII grade, i do fun stuff like the above in my free time. I should actually be doing inverse trigonometry, but I can't remember silly conditions :(
but I got it fixed and saved 2 copies
11:09
@Nick what limit?
I gotta finish up the latexing on my assignments. I got most of them just need to type it later today
@BalarkaSen
7 mins ago, by Nick
Can anyone tell me how to do the following *without* Stirling?
$$\lim_{n \to \infty} e^n \cdot \prod^{\infty}_{a=1}\left(a - \frac{1}{n}\right)$$
I've seen those in Discrete Math books
I think Number Theory has them too
@usukidoll: Oh god, it's like Deja Vu
too advance for you kiddo... need to train first
I kind of like pdes more than pure math subjects
I think pdes are the only computation course for undergrad senior math.. the rest is pure -_-
pfftt prove this and that
I know easy proofs the end
11:11
@usukidoll NT?
Number theory has no time to deal with kid's jobs.
Integral, limits and series are of no concern to NT
what about discrete math
it's there because I have seen the books
anyway I need to sleep
11:13
Is the asymptote of a function tangent to the function?
nighttttt
@usukidoll: Hey, i got the answer to that limit. It was $\infty$ ... but I had to use Stirling :(
@Alizter Might or might not be.
@BalarkaSen I think my argument is that it isn't because ultimately it's the limit and never the actual tangent.
@BalarkaSen: Wait, that question is too kiddy for you? I thought it was quite good.
11:16
@Alizter Who knows? The asymptote might be tangent at the function at, say, x = 1.
@BalarkaSen but not all functions.
@Nick I was kidding.
I was asked this but i didn't know how to answer.
@Nick I have almost 0 interest in limits, integrals, etc.
@Alizter So what's your precise question?
@BalarkaSen You are limiting yourself.
11:17
@Alizter Stop lecturing me and state your question.
@BalarkaSen it was more for the pun but whatever
The question was how I wrote it.
@Alizter: Some people like to argue that the asymptotes are tangents which touch the function at $\infty$. Now, these are the same people that say that two parallel lines intersect each other at infinite distance. :|
4 mins ago, by Alizter
Is the asymptote of a function tangent to the function?
It can be. Depends on what the function is.
Correct that is the question
That ws my answer ^
11:18
Ok issue resolved
@Nick Parallel lines do intersect each other depending on the space you are working with.
In CP^1, for example, they do.
@BalarkaSen: ... Thank you for blowing my mind away.
Now @Nick Find me the value of the hundredth derivative of $\sin(x)/x$ at $x=0$ :)
@Alizter: The answer is indeterminate ... or approximately zero for small values of x
@Nick errr? no
11:22
@Alizter Interesting. Do you have closed form?
@BalarkaSen For the derivative?
@BalarkaSen It is easier than you think
@r9m Do you have a value?
@r9m wat
analytic, yes, but so what?
@Alizter: Tell me the answer $\in (-0.5, 0.5)$
11:25
yes
@Alizter: Then, zero?
Ill give you a hint. cough taylor expansion cough
and it is not 0
r9m
r9m
^ that
@Alizter That still requires knowing a closed form
What is le value?
Oh oh
I can do laurent. meh.
1/100!
@BalarkaSen almost
@BalarkaSen don't forget coefficients from the derivative
11:28
like + and -?
no
$$\frac{\sin x}x =\sum_{n=0}^\infty \frac{(-1)^nx^{2n}}{(2n+1)!}$$
being lazy
Well, duh, yeah.
At $x=50$ you get 100th derivative
so $100!/101!$
@Alizter: The answer is 1/101 ... lol
@Alizter where's the 100! in the numerator coming from?
it's 1/101! not 100!/101!.
11:32
@Alizter: As a physicist, the answer is zero.
@BalarkaSen When you take the derivative of a function $nx^{n-1}$
what happens when you take the 100th derivative of $x^{100}$?
@Alizter Heh?
r9m
r9m
@Chris'ssis how about closed form of $\displaystyle \sum\limits_{n=1}^{\infty} \frac{H_n^{(2)-}}{n^3}$ ? :D
Why am I gonna do that?
@Alizter You have a taylor expansion. Coefficients are the derivative.
@BalarkaSen no.
11:34
$n!/(2n+1)!$
$(2n)!/(2n+1)!$
Hmm right the odd terms vanishes.
So yeah I get it.
@r9m I have that done.
r9m
r9m
@Chris'ssis Incredible !!! :D I am still struggling with it :( .. oh $H_n^{(2)-}$ stands for the alternating sum $\sum\limits_{k=1}^n \frac{(-1)^k}{k^2}$
@BalarkaSen: I was so close to the answer from the beginning.
11:37
@Alizter Moved on to analysis instead of algebra I see.
@BalarkaSen I can't do no algebra without passin' ma classes!
@BalarkaSen I have to do well in my exams to go to a decent uni
r9m
r9m
@Chris'ssis sorry typo .. $\sum\limits_{k=1}^n \frac{(-1)^{k-1}}{k^2}$
@r9m I need to check that.
Sad for you. I still have 4 years in front of me, so rock on
@Alizter
@Alizter: What course are you doing now?
r9m
r9m
11:40
@Chris'ssis okay :) .. plz tell me .. I'm stuck and I feel like an abandoned sack of rice :{
@BalarkaSen: If you can't do that previous limit thing, can you atleast tell me how to make wolfram evaluate it for me.
@Nick nopes. i forgot how to use W|A.
it's probably divergent though
@Nick Pure maths, Mechanics, Discrete, Statistics, Computer science, Physics and Chemistry
@BalarkaSen: It is. (Proved using strirling approximation) It evaluates to $\lim_{n \to \infty} \sqrt{2\pi n}$
I've got a quick set theory question to do with reading notation, @BalarkaSen. ^_^
11:45
Pure maths is mostly consisted of algebra-precalc and calc
@Khallil OK
@Alizter Such a pity
How would you read $\displaystyle \bigcup_{X \in \mathcal{P}(\mathbb{N})} X$?
@Khallil: Random question, Where's the backward E in latex and what does it imply in mathematics
$\exists$
@Khallik it's $\mathcal{P}(\Bbb N)$ itself, no?
11:47
I think it's just a quantifier that tells us something exists, @Nick.
@Khallil: Yes, what does it mean and how do I use it
Yep, but how would you read it?
@Nick it exists.
@Khallil Uh, union of all subsets of power set of integers?
Sorry, I meant union.
Yea, that.
yes, and i misread.
=P
11:48
Ok. How about the intersection?
Is it the intersection of all the elements of the power set of natural numbers?
@Khallil it's null, I bet.
Yep.
@Khallil: So, $\exists \space \text{Girl} \space \forall \space \text{Boy}\space \in \mathbb{WORLD}$
@Khallil well, yeah
@Nick No
Nope, @Nick.
11:49
@Khallil That is $\Bbb N$
and it is read to union of every set X such that X is in the power set of N
@Chris'ssis How about...
$$
\begin{align}
\sum_{n=1}^\infty(-1)^{n-1}\frac1n\sum_{k=1}^n\frac1{k^2}
&=\sum_{k=1}^\infty\sum_{n=k}^\infty(-1)^{n-1}\frac1{nk^2}\\
&=\sum_{k=1}^\infty\sum_{n=k+1}^\infty(-1)^{n-1}\frac1{nk^2}+\sum_{n=1}^\infty(-1)^{n-1}\frac1{n^3}\\
&=\sum_{k=1}^\infty\sum_{n=1}^\infty(-1)^{n+k-1}\frac1{(n+k)k^2}+\frac34\zeta(3)\\
&=\sum_{k=1}^\infty\sum_{n=1}^\infty(-1)^{n+k-1}\left(\frac1{k^2n}-\frac1{(n+k)^2}\left(\frac1k+\frac1n\right)\right)+\frac34\zeta(3)\\
&=-2\sum_{k=1}^\infty\sum_{n=1}^\infty(-1)^{n+k-1}\frac1{k(n+k)^2}-\frac12\zeta(2)\log(2)+\frac34\zeta(3)\\
@Alizter what is?
his orignal thing
It's $\mathbb{N}$, @Alizter?
the uniion is
11:51
@BalarkaSen, @Khallil: Are you saying my usage of $\exists$ is wrong or the obviously wrong statement is wrong?
@Nick There is not a boy for every girl
@Alizter well, yeah.
it is more girls at the moment i think
Yep, it is $\mathbb{N}$, @Alizter.
What about loners @Nick?
11:53
I just checked it.
It's N.
@Alizter: Ok, I'll fix it.
$$\exists \space \text{IceBoy} \space \forall \space \text{IceGirl}\space \in \mathbb{WORLD}$$
@Nick also existance of one thing does not imply the existance of another
@IceBoy: As far as you know $\mathbb{WORLD}$ is $\phi$
11:55
There's some real overkill of bad notation here.
@Khallil: lol
@robjohn Nice
It's a bad idea to watch a TV show and try doing math at the same time.
@Alizter I have a problem for you.
@BalarkaSen ok
11:57
@Khallil: It's worse doing math while solving a math problem at the same time.
@Nick Are they not done at the same time usually?
-_-
Solving a math problem IS doing math.
@Alizter: I'm making pseudo statements in my attempt to find the next "I am a liar" phrase. It would be wise to ignore the non-mathematical things I say.
11:59
@IceBoy: Again, tell that to my math textbook.

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