« first day (1608 days earlier)      last day (3708 days later) » 

17:06
@DanielFischer This unfunny comment got three stars, lol.
I found it pretty funny.
@JasperLoy People still go for Sumo Judge, maybe.
See you later, everyone.
Huy
Huy
My oven is taking ages to heat up. I'm hungry. -______-
@JasperLoy: I thought it was rather funny, lol.
17:17
Is there someone that can help me with an algorithm? :/
ADG
ADG
hi
wassup
@JorgeFernández I beat you by a landslide then.
@RobertCardona Hi!!! Could I ask you something about elliptic curves?
@evinda what kind ?
@ADG wassup mah dawg
17:21
@N3buchadnezzar what did you get?
6000 something, but my algorithm works better with a larger dataset. Generate 100 or so numbers and we could compare again.
@LeGrandDODOM Do you maybe have an idea?
ADG
ADG
can you people help me about harmonic numbers
and other non-elemntary functions?
@evinda I can't help you with this unfortunately
@LeGrandDODOM A ok... No problem...
ADG
ADG
17:23
anyone?
There are definitely people here who know about those, @ADG. I'd be patient.
(I'm not one of them.)
@JorgeFernández 66968, from chat log. Like I said run a bigger sample and we can see the difference more clearly.
ADG
ADG
so lets do a general discussion
But the problem is known to be np complete
ADG
ADG
17:25
can you people tell what current course you're doing? like PhD/MSc/BSc?etc.
Huy
Huy
@ADG: MSc
@JorgeFernández So? That does not mean it is not possible to optimize it. It is possible to make algorithms that find the optimal solution every time. Just because something is hard, does not make it impossible to get a good stab at it.
ADG
ADG
great what topic do they teach in bsc and msc general idea only, i'm impatient and excited
@JorgeFernández Try this one pastebin.com/GfAD1Y2h, 3 or 5 sublists/towers.
Huy
Huy
@ADG: Depends on the uni.
17:27
I made a greedy algorithm
ADG
ADG
atleast tell about yours?
ok, I'll try it
Huy
Huy
@ADG: I can choose from various different courses.
ADG
ADG
what did you choose? calculus? complex analysis?
nevermind, I don't know how to parse all those numbers without putting them in my array one by one
17:29
I wonder where the anon is these days.
Huy
Huy
@ADG: Analysis and complex analysis were compulsory courses during my BSc.
ADG
ADG
do they teach you to solve new integrals like some of the people at mse do?
Huy
Huy
@ADG: I don't know what you mean.
ADG
ADG
do they tell you about beta and gamma functions? when do you encounter them at first
Huy
Huy
@ADG: I encountered them in Analysis 2.
ADG
ADG
17:31
and other named functions like Ei/Si/erf/Bessel/Reimann Zeta/ etc?
@JorgeFernández what syntax do you need?
Huy
Huy
@ADG: I've seen Bessel and Riemann Zeta function, but I never needed to use them.
And the simplest is to just read it from file...
I don't know, I am using arraylists from java to store my numbers and a normal array for the towers.
read it from file? what is that?
ADG
ADG
hey what is happening? do you people study dual degree computer science(java) and maths? arraylist?
17:33
no, I just happen to suck at programming
ADG
ADG
@Huy is it interesting?
Huy
Huy
@ADG: What do you mean?
@ADG: What is interesting?
ADG
ADG
just slipped the wrong word
@JorgeFernández Either you do not know english, or you do not understand prpgraming beyond the simplest ideas. How do you write an arrayList in java?
But I'm going to start a computer science major halfway through my math major so I don't finish to fast.
@N3buchadnezzar it's the second one of the options you gave
ADG
ADG
17:35
studying maths at uni @Huy
I just declared the arraylist and then copy pasted each of the values individually
Huy
Huy
@ADG: Sometimes, sometimes less.
I can post my code
import java.util.*;
import java.math.*;
public class n3 {


/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

int[] towers= new int[3];
ArrayList<Integer> brick = new ArrayList<Integer>();
ArrayList<Integer> brickordered = new ArrayList<Integer>();
int k,c,d,M,e=0,e2=1;

brick.add(910648);
brick.add(181847);
brick.add(263803);
brick.add(145539);
brick.add(136069);
brick.add(869292);
brick.add(579705);
brick.add(549860);
brick.add(144955);
brick.add(853031);
ADG
ADG
should i then follow engineering or maths at uni?
Huy
Huy
@ADG: That really depends on your personal preference.
17:36
4
Q: Adding Multiple Values in ArrayList at a single index

Fahad Abid JanjuaI have a double ArrayList in java like this. List<double[]> values = new ArrayList<double[]>(2); Now what I want to do is to add 5 values in zero index of list and 5 values in index one through looping. The zeroth index would have values {100,100,100,100,100} The index 1 would have values {50...

ADG
ADG
BYE
All of my programming knowledge is improvised at the spot
ADG
ADG
and BYE
@N3buchadnezzar you lost me
@ADG bye
@JorgeFernández use stack excahnge codereview much more! Learn proper syntax and formating.. =) Otherwise you will ruin your programming later. Learning good habits from the get go is essential.
17:46
Consider $PO(1, n-1)$. In one exercise of Ratcliffe, he has mentioned the quotient group $O(1,n-1)/\{\pm I\}$, claiming there is an isomorphism between it and $PO(1, n-1)$. Is it safe to assume that this is a typo? (Ratcliffe has always written $I$ to mean $$\begin{bmatrix} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{bmatrix}$$ which does not make sense seeing as $II = J$ where $J$ is the identity matrix under the Lorentzian inner product.)
Can you define $PO$? I don't know the terminology.
Positive orthogonal group.
In this case it is Positive Lorentz Orthogonal, thus the $1, n-1$ rather than $n$.
I guess I don't know enough about these groups to say anything intelligent. Sorry.
Are you familiar with the Lorentzian inner product? I am merely looking for confirmation that, if we have replaced the Euclidean inner product with the Lorentzian one, the quotient group as it stands now does not make sense.
@Andrew: Why doesn't it make sense?
17:49
$II = J \not\in \{\pm I\}$
That's not the right equation to preserve the inner product, is it? Shouldn't it be $AJA^\top = J$?
I have to admit it doesn't make much sense to me that you're writing $I^2 = J \neq I$, since $I^2 = I$...
howdy @Mike @Jasper
@TedShifrin Hello. Did you have a quarrel with Bill a while ago? I was not in the room.
@MikeMiller, we are working in Lorentzian $n$-space. $I^2 \ne I$ here.
17:53
@evinda, What's your question?
I left a message and haven't been back since until now. I was fed up with him.
$x \circ y = -x_1y_1 + x_2y_2 + \cdots + x_ny_y$
How are you defining matrix multiplication? It shouldn't be different just because we've equipped the space with a different quadratic form...
We're confusing matrices with the bilinear form $J$, @Mike @Andrew.
But clearly I should stay out of this.
17:54
Sometimes I think that anon and mike are the same person.
@TedShifrin massage, angry massage
We're not, @Jasper.
The orthogonal group for an inner product is defined by the equation I wrote above.
@JasperLoy Everyone here is the same person Jasper. You just need to wake up.
You being punny, @N3B?
17:54
I wouldn't mind an angry massage.
@TedShifrin I tried
Massage? There are kids in this room, lol.
It's their choice to be here.
@Jasper: The average age seems about 10 higher than usual.
I guess kids still have free will.
17:56
I have never gone for a massage, though several of my friends have, and done naughty things that go along with it.
@TedShifrin Mental age seems to be about half that.
Including that of some people older than I, apparently, @N3B.
@TedShifrin There is a difference in being childish and senile.
Massages don't usually come along with naughty things in the US, @Jasper.
Though, of course, there are some places that do do that... but they're not the norm.
Interesting quandry. Ignoring the answer from one of my other least favorite people, this question raises a question: Is the student expected to understand to show containment both ways?
17:57
@MikeMiller The cheaper ones here do.
@JasperLoy How about a sad ending?
Huh? What's wrong with RL, @Ted?
@TedShifrin What's wrong with M.Lewis ?
First, he does everyone's homework to show off. Second, his "fiat lux" drives me nuts. But we are polite to one another. :)
hi, ledodo :)
Since everyone makes me cranky, you think I should quit showing up here for a year?
Oh, wait, I have to make sure my students don't get their diff geo homework done here this spring.
@N3buchadnezzar lmao
I haven't seen him doing others' homework. His fiat lux is stupid, but I see it rarely enough that it doesn't at all bother me.
18:01
@TedShifrin Do I make you cranky, sad or lose faith in humanity? You only get to pick two.
@TedShifrin, let me go about this from scratch (mostly for my own sake.) If $A$ is Lorentzian, then the the columns of $A$ form a Lorentz orthonormal basis of $\mathbf{R}^{1,n-1}$. For the equation $A^T J A = J$ to make sense, we need to define matrix multiplication as one would expect in Lorentzian $n$-space. Then $PO(1, n-1) / \{ \pm I\}$ does not make any sense, $\{ \pm I \}$ is not a group under Lorentzian matrix multiplication.
@N3buchadnezzar I see what kind of things you have been watching.
No, @Andrew, I think you're confusing things. You use regular matrix multiplication.
@Ted Surely the answer to this is "every differential geometry book ever"?
No comment @N3B :D
18:02
@JasperLoy 7/10 would need more puddi puddi.
Not quite, @Mike. Any graduate text, yes. I don't do it in my undergraduate notes. That belongs in a manifolds-based course, not the typical undergraduate course.
Fair enough.
@JyrkiLahtonen
Ohyes, that makes sense, @TedShifrin. The very definition of $J$ allows regular matrix multiplication to make sense, had we multiplied as I expected it'd make less sense. Thanks.
(If any sense at all.)
By the way, why does Rudin use J to denote the positive integers?
18:05
You're most welcome, @Andrew.
He's not alone, @Jasper. That may come from somewhere in Europe.
@JasperLoy Freitag (und Robinson), Complex Analysis I.
@JasperLoy, its convenient at times. Had my oral exam recently, writing stuff like $\sup_{i \in J_n}$ saved some time, and the sensor couldn't complain.
@RobertCardona Could you take a look at this: http://math.stackexchange.com/questions/1078055/elliptic-curve-component-of-point ?
How could we find the tangent of the elliptic curve at the point $(x,y)$ ?
@JasperLoy He is crazy like a fox.
chat.stackexchange.com/transcript/message/19288831#19288831 No one addressed my real question; y'all got distracted by Robert Lewis. Is the intent of such an exercise to prove the two sets are equal or just to verify one is a subset of the other?
18:08
Day 1: Decided to delay building the float untill I have proven the Cauchy-Gorbats theorem.
Day 2: Freitag was eaten by a cannibal, but now I finally have the propert fundations for the Rieman mapping theorem.
Goursat, I guess you mean, not Gorbats.
Cauchy-Dingbats Theorem :)
@TedShifrin I think the question can be ambiguous.
@TedShifrin In my experience from such courses one usually shows equality directly, this seems to be a pre-prooftechniques course.
Huy
Huy
@TedShifrin: Is it common in the US to have differential geometry courses that are different for graduates vs. undergraduates?
18:10
@Andrew: I have a similar question in my differential geometry course, and there it is my intent that they understand they're getting the entire hyperboloid :) But I tend to agree with you, @Andrew, that most likely it's asking just to check $X\subset Y$.
@N3buchadnezzar Your English is terrible.
Yes @Huy
Undergraduate diff geo is usually taught (see my notes) for students — somewhat sophisticated, perhaps — who know basic multivariable and linear algebra, certainly not the inverse function theorem or manifolds. We cover just curves and surfaces in $\Bbb R^3$.
@TedShifrin "My differential geometry course" - student or lecturer?
Lecturer, sorry, @Andrew :)
I am neither student nor lecturer currently. Just a banana.
Huy
Huy
18:11
@JasperLoy: Flagged for banana.
I still say it's time to be a mango, @Jasper.
Ugh at the plane crash yesterday, @Jasper.
@TedShifrin What plane crash?
No, that's great, I can spam you for advice: I did Topology and Real Analysis simultaneously this semester, and while that went fine, the easier course in Multivariable Calculus suffered a bit. I know the main ideas but lack computationexperience. Will this be a problem when I go into manifolds?
Oh, I don't follow the news.
in the Java Sea yesterday, @Jasper.
18:13
@JasperLoy Where do you live ?
I already have too many things to worry about, so I don't read the news anymore and get more upset.
Yes, @Andrew, you want to ramp up and learn multivariable analysis — inverse and implicit function theorems, derivative as linear map, etc.
@LeGrandDODOM I live somewhere in Asia. I would rather not say exactly where because there may be some spies.
@TedShifrin Those are the few parts I actually do know from multivariable :) Will however retake the exam in February, so my memory will be refreshed regardless.
18:16
btw, @Andrew, one of my most gifted students (who took undergraduate and a year of graduate diff geo from me) had your name — more likely, you have his :P
@TedShifrin Anyway, I don't get upset over accidents or natural disasters. I get more upset over politics.
Andrew Thompson or just Andrew? Its a pseudonym I picked at random.
the whole name, although he went by Drew ...
I don't want fellow students to see all the stupid questions I ask :)
Hm, that's quite a coincidence.
Huy
Huy
@AndrewThompson: Why would that be a bad thing?
18:17
I don't know why everyone is so preoccupied by being thought stupid ... Sigh.
Huy
Huy
It's like avoiding to ask a question in class because you're scared others will think you're stupid. What is this, kindergarten?
I answered a diff geo post earlier this morning from a guy whose teacher totally sluffed over the Euler-Lagrange equations from calculus of variations and said it was trivial, and the students were too petrified to ask.
@Huy Your spelling is terrible.
@Huy: It's the behavior (or behaviour) of many teachers, I'm afraid.
oh hush, @Jasper
@Huy I definitely do not avoid asking questions in class. Its all in my head, but I prefer remaining anonymous online.
Huy
Huy
18:19
@AndrewThompson: It's the same online, only that there's even less of a chance of other people thinking you're stupid than in class, imo.
you are entitled to be anonymous, @Andrew, but we're quarreling with your rationale.
That is perfectly understandable.
Well, @Ted, if I remained anonymous I would feel better about telling people to ----- ---- ------ ---- ------- ----.
I expected that making a video of my classes would stop students from their questions and humorous interjections, but, thankfully, it didn't
well, @Mike, what do you really want to say to me?
You're not the ones in question, since I say that to you in private :)
18:20
@MikeMiller I think you should just go and XXXXX.
I notice no one backed up my irate comment :P
Have you ever recommended MSE to your students, @Ted?
I recommended MSE to my Topology TA. "You'd be really entertaining to have there."
A lot of them are here, @Mike, as you know. I've ranted about people who post homework questions and then turn in posted answers as their own work.
18:21
Is Math the only SE site to complain about homework?
No, @Jasper.
Many other sites are much more proactive with disallowing it, e.g. physics and chemistry.
I conjecture physics and stackoverflow suffer from the same.
SO gets much, much more of it.
um, @Mike, a bit off topic? I vote to close.
@MikeMiller Ah, this is news to me.
18:22
How could i describe the space of all $2\pi$ periodic functions, that are infinitively differentiable?
I suspect that because there are infinitely more low-level students in math than in Physics or CS we have a bigger problem.
That's also known as $C^\infty(S^1)$, @N3b
Infinitely differentiable functions on $[0,1]$ so that $f^{(k)}(0)=f^{(k)}(1)$ for all $k$?
@MikeMiller $$ \{ f \in C^\infty ; f(x) = f(x+2\pi)\} $$ Seems silly
Huy
Huy
@TedShifrin: Are there? There are more physics or CS undergrads at my uni than maths. Or do you mean undergrads with questions in mathematicians, which then would also include physics, CS, engineers, etc?
18:24
@TedShifrin Consider $x$ on that interval. Doesn't work.
I'm referring to lower level math, @Huy. Most everyone in the world has to take 12-14 years of math in school.
@TedShifrin I created a mathforum for my Uni last semester, hoping to create some sort of community for the new students.
@N3b I dunno what's silly about mine. It's the same as the space of smooth functions on the circle.
Oboy did I have to remove many solutions for the mandatory exercises.
It's not true that we have a bigger problem than SO, @Ted. It's about the same.
Hi, @Behaviour. I trust I'll see you here for UTC New Years?
18:25
Odd, because of my reasoning, @Mike.
@JasperLoy For the record, I had no discussion with Ted, only Pedro (and I agree with Ted about "fiat lux"). It seems that many people misinfer that because I raise certain points for discussion that those are my personal views. But that is often not so (e.g. I don't agree with JDH's famous "squirrelly" viewpoint, but I understand and respect it, and I think it deserves to be better known to help devise optimal compromses)
@MikeMiller But yours mentions nothing about periodicity??
What do you mean $x$ on that interval? @Mike
Periodicity is inherent in the circle, @N3B
scratches head
exp(i theta) hmm. Yeah ok.
@BillDubuque OK. For the record, I like having you on this site.
18:26
@N3b That's the ticket.
@MikeMiller Not percentage-wise, though. A HW dump on SO is common, but it also sticks out from the rest of questions in a few ways... and generally, does not live long.
Yes, marking the calendars for new hats as usual.
Fine. You win.
@BillD: Thanks for clarifying. Much as you complain about @Pedro's tone, though, yours is often didactic and condescending. And JDH's attitude is fine if one gives up requiring graded homework, but I have yet to do so. Luckily, I'm retiring, in part because of frustrations over such matters.
@Behaviour Heya. How about closing HW questions that have been asked earlier, and moving good answers into great ones. Eg making the list of iconical questions CW
Was that concession to me, @Mike?
18:28
Yes.
You had me very confuzled!
BTW, @BillD, I was at MIT 1970-74 as an undergrad and then as a postdoc 79-81. I miss the place.
@N3buchadnezzar Merging questions is difficult. Requires mods. Notation rarely matches.
@Behaviour It's easier in some fields.
@MikeMiller Before it's deleted, see the worst ever attempt at pizza hat.
If you'd ever been an editor, @N3B, you'd know that what you just suggested is a monumental task.
hi @Behaviour
18:29
Yikes.
@TedShifrin Hire chinese persons. There are millions of them.
The OP has 9000 score in C++ tag.
flagged for bad taste @N3B
Yes, I saw.
@Ted No doubt about that! I wear too many hats, I'd much prefer to wear only the humble mathematician hat.
18:32
@N3buchadnezzar I'd rather let duplicate links and search function do the work of consolidation. This reminds I should work on an update to mathindex.wordpress.com ... cya
Still using the 2013 theme in almost-2015? Yikes.
That is sooo 2012.
@Behaviour It really grinds my gears when well established users tend to answer HW questions, they have answered earlier instead of taking the time to mark them as duplicates..
@Behaviour That site is a good idea. To avoid duplicates I presume?
It grinds my gears that 20+K users answer homeworks and low level questions at all ... at least without waiting a long while to give the newbies a shot.
2
@TedShifrin That sounds like me, except that I don't have 20k, lol.
18:36
@Behaviour Sire.
Well, really you do, @Jasper.
mr @Pedro :)
@TedShifrin Me too. I esp. miss the ability to wander into Rota's office ...
@BillDubuque Is jealous.
You do realize this is not a duplicate of the question it was marked to be a duplicate of? @Behaviour
Might seem poor quality, but it kinda isn't.
@BillDubuque That ODE book by Birkhoff and Rota is terribly expensive, lol. And also many typos.
I mentioned several times this semester (learning/teaching probability for the first time) that I avoided taking Rota's course when I was an undergrad because he was so notoriously a prima-donna (I won't elaborate here). I was stupid. I should have taken it.
18:37
User is showing work, albeit ugly.
@PedroTamaroff I don't think I've ever heard that accusation before. Of what?
@BillDubuque I'm saying I am jealous.
That was ambiguous, @Pedro :P
I capitalized accordingly!
Huy
Huy
@PedroTamaroff: A "theoretical physicist" in physics.stackexchange chatroom just wrote this message: "All of the mathematics I use is PEMDAS" - I thought you'd like to know.
18:39
@BillDubuque Italics indicate something one is doing. It comes from IRC standards from long ago; /me would change your message to <username> is <message>
@Huy Cocks gun.
Huy
Huy
@PedroTamaroff: Fire at will.
It carried forward from there to message boards, and then, apparently, to the StackExchange chatrooms.
Points at Huy.
See you guys. Off to play tennis.
18:41
@Behaviour Refresh my memory: one can explicitly write down a conformal map from the interior of a polygon to the unit disc using integrals of some kind, yes?
@MikeMiller Yeah, I realized that with hindsight (I never used IRC or related stuff)
@TedShifrin pockettennis
@TedShifrin Have a good one, eh!
I used it just enough to learn a few worthless factoids.
18:54
are people online here ? I have a series question
Is it serious, too?
Huy
Huy
@Studentmath: What series question isn't serious?
@Studentmath are you asking me ?
@Huy I don't know, but maybe we just found the one
@Huy "Determine the silliest series."
18:55
@Danish ask the series question, maybe someone will be able to answer
Huy
Huy
@MikeMiller: Where's Chriss'sis when you need her?
lolx no no it's not that kind of silly it's actually from my book
@ted @mike I just got a reply again from my beloved John Lee! He says the second edition of Riemannian Manifolds may be out in 2017!
Q: Sum to n terms the series 1⋅5+5 ⋅11+9 ⋅17+…
I can solve all the rest part of this question but I don't know how this sum is equal to the product of general terms of whole parts and decimal parts
Huy
Huy
@DanishALI: What is your solution?

« first day (1608 days earlier)      last day (3708 days later) »