Mathematics - 2015-02-04 (page 2 of 6)

Alexander Gruber

02:00

@Axoren He's not really user1111?

Ted Shifrin

heya @AlexG

Alexander Gruber

@TedShifrin Hi there. :)

Axoren

@AlexanderGruber He's probably user1111, but Julian think's he's someone else, too.

Alexander Gruber

@Axoren I am 99.9% sure his real name is not user1111

Julian Rachman

I know who he really is and he is in this chat room now

Ted Shifrin

02:01

well, @AlexG, you're sure I'm not Ted Shifrin, too :D

Julian Rachman

@Alexander I know his real name

Axoren

@AlexanderGruber I'm 100% sure. I'm looking at census documents across the globe.

Alexander Gruber

You can't trick me, @Ted.

Axoren

Not a single human being has been named user1111 in the past century.

Alexander Gruber

@Axoren You should name a kid that then.

Mike Miller

02:02

User2 and User7 are both popular names in Wisconsin, however.

Axoren

@AlexanderGruber That would be too edgy. He'd never survive in a public school.

It's practically asking him to do drugs at a young age.

Julian Rachman

LOL this is getting weird

Alexander Gruber

@Axoren See, you're setting him up to be an early boomer

Julian Rachman

@AlexanderGruber @Axoren @Mike I named him above ^^

Axoren

Very few people care, @JulianRachman :P

We only have evidence of one person caring :P

We're all kind of immune to this sort of thing since @Hippalectryon and @Ramanewbie were going nuts a few days back

Same avatar and everything.

Julian Rachman

02:07

@Axoren LOL. Ya. I dont really care much either. It is jsut that I saw the question he had asked on MSE and I remember us asking the question together because of one of those reference citations on my blog.

0

Q: How to find out the first name of a professor whose home page lists only first initial?

This is probably a soft question. I am interested in complex analysis, and I want to ask the first name of this person, S. Ponnusamy, whose name I wish to mention in a paper. What is the best way to go about asking such stuff?

personal-name

Pedro Tamaroff

@JulianRachman Why do you care so much about this?

user105491

I do not appreciate such things being said about me online

Alexander Gruber

@PedroTamaroff His coauthor is Vladimir Putin.

Mike Miller

@JulianRachman If he is harassing you, flag him and report it to the mods. It should not matter who user1111 is, they'll look at him for harassment. If he's not harassing you, it shouldn't matter who he is.

user105491

I would like a moderator to remove Julian Rachman's comment above about me

Julian Rachman

02:09

I dont know I just took Sherlock Holmes to the next level. :)

Alexander Gruber

@SanathDevalapurkar Flag it.

Pedro Tamaroff

@SanathDevalapurkar What comment?

user105491

Him saying my name

user61230

[pops in] whazzgoinon

Mike Miller

You use your name.

Ted Shifrin

02:09

You guys are supposed to be best friends. Come on, kids!

Julian Rachman

Ill jsut delete it

Ted Shifrin

Are you making trouble, @Emrakul? :D

Mike Miller

This is silly. Who wants to talk about math?

user105491

me

Mike Miller

@Emrakul Tell me a math story.

Axoren

02:09

I guess that one.

Pedro Tamaroff

Ignores the kids.

Mathy Person

Would -6 be correct? math.stackexchange.com/questions/1132334/…

Ted Shifrin

Finally: Pedro is ignoring me :D

Pedro Tamaroff

@TedShifrin You're not a kid!

Alexander Gruber

Well @Mike, let me tell you what buddy

Ted Shifrin

02:10

Aw, I'm not? :(

user61230

@Ted Just tellin' a bad joke about math! Which is a crime where I live, so yes!

Alexander Gruber

I'm thinking about being a topologist.

Julian Rachman

Ok. Well. I am sorry for all the trouble. My crazy hunches get in the way of my "doings"

:)

Pedro Tamaroff

@AlexanderGruber But topology has infinite indecomposable continua.

user61230

@Mike Have you heard the story about the three medieval kingdoms on the shore of a lake?

Julian Rachman

02:11

Woopies

user105491

@Alexander if you don't mind me asking, what year of university are you in?

Alexander Gruber

@Emrakul do you live in a physics department?

Mike Miller

no, @Emrakul, but be warned that this better be good.

Alexander Gruber

I'm a 2nd year graduate student, @Sanath.

user61230

@Alexander SHHH. they don't know I'm still here [hides]

user105491

02:11

Ah, nice!

user105491

So what were you studying until now?

Alexander Gruber

@Emrakul Trust me, they'll never take you back now.

user105491

something related to topology, i presume

Alexander Gruber

@SanathDevalapurkar Finite group theory.

Ted Shifrin

Wow, really, @AlexG? I'm truly shocked (just don't tell @Hippa).

user61230

02:12

@Mike Ahh, I see! Well, there were three medieval kingdoms on the shore of a lake, and they had been fighting for many years.

Pedro Tamaroff

Remembers the "I'm shocked" meme.

Alexander Gruber

I'm thinking about doing persistent homology... so, applied algebraic topology

Ted Shifrin

glares at Pedro

Mike Miller

persistent homology is rad, you were looking at that last year, right?

you should teach me about it.

Pedro Tamaroff

@AlexanderGruber Just don't do bothersome homology.

Julian Rachman

02:13

@Alexander [kneels and bows down]

user105491

@Alexander I know more about homotopy theory, to be honest

user61230

@Mike There was an island in the center of the lake - a most beautiful island, filled with beautiful flowers and chests of riches. The kingdoms decided they would do battle, and the winner would claim the island and its contents. The first kindgom had 12 knights, and each knight had five squires. They hurriedly polished their many pieces of armor, cleaned their horses, and cooked their food.

Alexander Gruber

@MikeMiller It's pretty cool. It's got that nice... chunky feeling, the same one as FGT. But unlike FGT, it has applications.

Mike Miller

@Emrakul This is rarely how war works but I shall suspend my disbelief.

user61230

@Mike The second kingdom had 20 knights, and each knight had ten squires. Everyone at this camp was also preparing for battle - and even more hurriedly than the first. But at the camp of the third kingdom, there was but one lonely knight with his one squire.

user61230

02:15

Shhhh, I'm telling a story!

4

Ted Shifrin

I didn't know I'd come for a bedtime story ...

Axoren

It's always bedtime somewhere.

Mike Miller

@Axoren :)

Alexander Gruber

@MikeMiller Basically what you do is look for patterns in data by building all these funky complexes. You grow balls around all the points and keep computing Betti numbers, see how long stuff sticks around.

Julian Rachman

[sits down with my calculus pillow and topology mug with hot chocolate]...

Ted Shifrin

02:16

That's why I always say good night to @Mike, @Axoren.

Julian Rachman

lol

user61230

This squire needed only to cook for two people: himself and his knight. So he grabbed his pot and hung it off a tree by a thick rope, dangling above the fire. He busied himself making a meal, while the knight spent time polishing his armor.

Alexander Gruber

The idea is you're figuring out what topological space the data "probably" came from

Mike Miller

@AlexanderGruber I know the basic idea (I saw a talk Gunnar Carlson gave about it)

user105491

Can things like moduli spaces be used?

Ted Shifrin

02:17

One of our new assistant profs is running a one-hour undergraduate research seminar on big data and homology, @AlexG.

Mike Miller

I'm more interested in the meaty parts.

Julian Rachman

@Pedro It seems as though your are left out. lol. we still see you...

user105491

it seems very related to it

Alexander Gruber

@MikeMiller Yeah- right, the current idea is to maybe become that dude.

user61230

@Mike In the morning, the battle came. The three kingdoms sent their squires out to fight. The battle raged for hours, and the blood splattered, turning the water of the ocean red. Yet at the end of the battle, the one squire remains. This only proves that once again, the squire of the high pot and noose is equal to the sum of the squires of the other two sides.

Mike Miller

02:17

to become Gunnar Carlson?

Axoren

This one squire can feed a whole army! Those first two kingdoms have such a wasteful military.

Mike Miller

Have you seen Lost Highway?

Pedro Tamaroff

@JulianRachman What?

user61230

[flees]

Alexander Gruber

@TedShifrin Have him record it. I can guarantee an audience of 1

@MikeMiller I love david lynch. :p

Julian Rachman

02:18

@Pedro I didnt see you comment

Pedro Tamaroff

On what?

Julian Rachman

anything yey

Ted Shifrin

I doubt that's possible, @AlexG, but I can give you a few names of smart undergrads if you want to contact them about it.

Julian Rachman

i mean

Mike Miller

@AlexanderGruber So you're proposing a sort of Lost Highway situation, with you in place of Bill Pullman.

Pedro Tamaroff

02:18

That's because I'm busy.

Julian Rachman

Oh. HW?

Alexander Gruber

@MikeMiller I was headed towards being the mystery man with algebra. :p

@TedShifrin Everything is possible in the wonderous world of smartphones

Mike Miller

haha

i'm going on a jodorowsky kick soon.

never seen a single of his films.

Ted Shifrin

We're already 4 weeks into the semester, @AlexG.

Kevin Driscoll

@Ted Feels like more than that

Alexander Gruber

02:21

Why, I was just informed that I'm going to have my discussion sections recorded by a DSO student, which is apparently part of my contract.

Ted Shifrin

@Kevin: It's already going way too fast for me in terms of getting my house ready to sell. And my calculus exams today were quite disappointing. sigh

Alexander Gruber

@MikeMiller I haven't either.

Mike Miller

i just got over my tarkovsky kick. hell of a director.

Сталкер is now one of my favorite movies.

Kevin Driscoll

@Ted Serious question. Are they always disappointing?

Ted Shifrin

Oooh, @Mike is typing in Cyrillic.

user105491

02:22

Hey short question

Mike Miller

Movie's name's in Cyrillic.

user105491

asked in the homotopy chat room already

Ted Shifrin

No, @Kevin. And some were quite pleasant. But most of these kids got A's last semester, so I don't expect scores in the 50s this semester :(

user105491

but does anyone have advice on how to make poster boards for math research?

Alexander Gruber

@SanathDevalapurkar Well

The first thing you do is you get a poster board

user105491

02:23

yeah...

Alexander Gruber

So then you print your paper

user105491

that was unexpected as well

Alexander Gruber

No pictures, 12pt

And line it with it like wallpaper

user105491

That's basically just sticking individual pages of a paper next to each other

Ted Shifrin

12pt seems awfully small, @AlexG

Kevin Driscoll

02:24

In this chat, we give people terrible advice!

4

Ted Shifrin

LOL @Kevin

Alexander Gruber

@SanathDevalapurkar Yeah, exactly. Dont forget to put some blank printer paper next to your display in case people forgot to bring theirs for the exercises to the reader.

Mike Miller

@TedShifrin is right - if you want your text to be visible, you need 16pt. More than that is crass.

user105491

Alright

Axoren

How do I into Mathematica?

Ted Shifrin

02:25

Wow, I got starred for being right.

user61230

my gods, the stars are everywhere

user105491

but most of my paper is text

user105491

how do i make it seem interesting?

Kevin Driscoll

For a posterboard? I think the titles and such hould be more than 16 pt perhaps

user105491

and not filled with equations?

Axoren

02:25

Is it all pretty much self explanatory, or do I need to learn a language?

Mike Miller

(People will take larger font as an insult - you're implying they have bad eyesight.)

Alexander Gruber

@SanathDevalapurkar You could put it in typewriter font

People love that

It's wacky

Axoren

@MikeMiller But the last thing you want is someone leaning over the presentation table because they can't read it from a distance.

Ted Shifrin

Like all computer languages, there is syntax, @Axoren. I imagine those of you who program in C++ will find it easy to learn.

Pedro Tamaroff

@SanathDevalapurkar My experience on the internet is people like cats. Try putting pictures of cats in it.

Kevin Driscoll

02:27

@SanathDevalapurkar I think what you should do is create an original display for your posterboard based on your paper. Don't try and cram too much information on the board. The important thing is to have a well-presented introduction, a summary of the results, and a good discussion of what they mean

Axoren

@TedShifrin I was assuming it was mostly functional. Are there any weird special forms, though?

Mike Miller

@Axoren Well, if people actually do have bad eyesight, you should have portable versions of your poster they can look at from up close.

Axoren

@MikeMiller You mean printouts?

Ted Shifrin

There are great help pages and examples, @Axoren.

Mike Miller

Yes, but in trifold, @Axoren

Axoren

02:28

@TedShifrin I'm installing it now, so I have no interactive feedback, yet. I just wanted to get some vague notions of what I'm getting myself into.

Alexander Gruber

But, more seriously @Sanath, do basically the opposite of all that and you'll be good. Lots of pictures. Post your full result so that it's available, but don't focus on the in depth parts of the actual paper, people just want to get the gist. Try to act like you're writing something for Popular Science.

Ted Shifrin

On my webpage you can find a basic introductory primer that has some useful stuff, @Axoren.

Alexander Gruber

@Axoren If you want to learn Mathematica I'll teach you but you need to come up with some stuff you wanna do

Axoren

I have plenty of stuff I want to do, @AlexanderGruber. Lol.

I have plenty of impossible functions that are stupid, but they will eventually serve a practical purpose.

Kevin Driscoll

@Axoren Mathematica is mostly very high-level in terms of language and syntax. There are just a few structures that basically everything follow

Ted Shifrin

02:30

The weirdest thing is programming functions with # as the variable :P

Alexander Gruber

@Axoren Good, let's plot 'em

user105491

@Alexander @Kevin Thanks! @Pedro I'll do that as well!

Alexander Gruber

What's the first one

user105491

:-)

user105491

i have never used mathematica before

Kevin Driscoll

02:30

@Axoren You can do anything with loops and stuff you can do in C++, but there's usually a better way to do it in Mathematica

Alexander Gruber

@TedShifrin pure functions are so awesome

Axoren

@AlexanderGruber You don't understand...

user105491

in fact i have never used a programming language for math before

Axoren

I'll link you one.

user105491

i suck

Axoren

02:30

@AlexanderGruber math.stackexchange.com/questions/1128485/…

This is the most recent one.

Ted Shifrin

@Axoren, as I said, there is some cool stuff in my primer :P

Alexander Gruber

@Axoren Ok let's plot it

Axoren

@TedShifrin I'm going to look at it right now.

Kevin Driscoll

@Axoren Unfortunately things like sum/product over primes is kind of difficult to implement

Actually now that I think about it, there may be a way using boolean and if statements

Axoren

@TedShifrin How do I open .nb's? Is that the Mathematica Format?

Kevin Driscoll

02:32

@Axoren It is

Ted Shifrin

Mathematica opens 'em just fine, @Axoren

Axoren

@TedShifrin Still downloading it, I was trying to read it like a webpage.

Ted Shifrin

nope, @Axoren, need at least the Mathematica reader. :)

Axoren

Oh lord... Mathematic emailed me, apparently.

Kevin Driscoll

I'd just like ot say that me and hypergeometric functions do NOT get along

Axoren

02:34

How am I screwing this up so badly... It's just a download...

I'm like my parents right now.

Ted Shifrin

Does your university give you free access to it, @Axoren?

Julian Rachman

Hey. I had a math question

Kevin Driscoll

@Axoren HOW DO I INTERNET!?!?

Ted Shifrin

We're not open for math questions, @Julian.

Axoren

@TedShifrin That's exactly what they're emailing me about... Are they just sitting at their computers or something?

Alexander Gruber

02:35

@Axoren They can be confusing with their little access code things... follow their directions

Axoren

Waiting for someone to try and download the non-student version?

Ted Shifrin

Your university needs to vouch that you're a bona fide student for you to get access to the actual Mathematica, @Axoren.

Kevin Driscoll

@Julian Unless you want wrong answers, I wouldnt ask math question here.....

Axoren

Oh my god.

Oh, well, I don't think I should be showing that.

Ted Shifrin

Wolfram makes its money by being bitchy :P

Axoren

02:36

That seems like it was sent personally.

Ted Shifrin

Yup, it does. Who knows what you were doing ...

Kevin Driscoll

Ya Wolfram doesn't like it when you try and use Mathematica to watch pr0n......

Julian Rachman

@Kevin Haha. I trust you guys. I mean, do I have anyone else to ask?

Axoren

@KevinDriscoll 8008135

Kevin Driscoll

@Axoren hold on just lemme get my calculator......

Julian Rachman

02:38

I am the minority of mathematics

Alexander Gruber

Kevin Driscoll

@AlexanderGruber Is that the product over primes function?

Axoren

@KevinDriscoll I think it's a sex joke.

Julian Rachman

So............. Can I ask my question?

Alexander Gruber

@KevinDriscoll Yup, as the number of primes increases

Kevin Driscoll

02:40

@Axoren I don't think so. It looks like a finite polynomial represtnign the first several terms of your function

Alexander Gruber

Goes up to the first 100 primes, seems to be converging pretty well

Ted Shifrin

I had to write a tiny program for Mathematica to only put in terms for the primes; do you know a shortcut for that, @Alex?

Kevin Driscoll

@AlexanderGruber How did you list the primes? Is guess theres a PrimeQ[] functions or maybe you just pre-made a list...

Haha, @Ted and I had the same question

Ted Shifrin

I used PrimeQ for my recursive call.

Alexander Gruber

@KevinDriscoll I used Prime[n]

Mike Miller

02:41

any CAS worth its salt nowadays has a prime(n).

Julian Rachman

Is Artin's Algebra a good book for abstract algebra?

Kevin Driscoll

Ah, returns the nth priem I imagine

Mike Miller

indeed

Ted Shifrin

yes, @Julian. I'm extremely fond of it.

Alexander Gruber

This was actually the full code I used,
f[x_, n_] := Product[(1 - x^2/Prime[i]^2), {i,1,n}]
g[n_] := f[#, n] &
L = Table[Plot[g[n][x], {x, -10, 10}, PlotRange -> {{-10, 10}, {-5, 20}}], {n, 2, 100}];
Export["prf.gif", L, "gif"]`

Julian Rachman

02:44

@Ted That is great! I just found out about it when watching MIT's lectures on Abstract Algebra

Axoren

Oh my god, that's a mess.

I have to learn that syntax?

Alexander Gruber

@Axoren Not really

Kevin Driscoll

@Axoren In mathematica it looks nicer

Axoren

@KevinDriscoll I'll take your word for it

Kevin Driscoll

It's also quite compact. 4 lines isn't much of a program in any language but Mathematica.

Axoren

02:45

Still trying to install it

Alexander Gruber

You can make it display better, and I also added a little layer of complication that you won't necessarily have to

Axoren

Wait, how big is this thing installed?

Alexander Gruber

by making the $g$ function

Ted Shifrin

yeah, you didn't need that at all, @AlexG ... you were just showing off #.

Axoren

What is pound/hash/sharp?

Alexander Gruber

02:46

@TedShifrin I didn't need it but it is better semantically, once you understand it

Kevin Driscoll

@Axoren Thats a special MMA syntax. It allows one to define a pure function

Ted Shifrin

<--- prefers impure functions

Axoren

Wasn't it already pure?

Alexander Gruber

@Axoren A pure function is a function where you don't explicitly make the variable

Axoren

OH

Alexander Gruber

02:47

Let me give you an example, the identity function is $f(x)=x$

Axoren

So it's a function object.

Not a function call

Alexander Gruber

as a pure function you'd just write #&

Right

Axoren

Got it.

Alexander Gruber

The # is where the variable goes, the & shows where the pure function ends.

Ted Shifrin

Real mathematicians talk about $f$ and $f\circ g$, not like calculus classes with $f(x)$ all the time.

Axoren

02:48

So, functions defined as "f[x]:="

Those aren't first class objects?

Kevin Driscoll

@TedShifrin Don't forget! $f(k)$ is the fourier transform of $f(x)$!

Mike Miller

what? k?

get out of here.

Ted Shifrin

smacks @Kevin

Alexander Gruber

@Axoren There's a lot of subtlety in what you just asked :p

Mike Miller

frequency is $\xi$. don't be silly.

Alexander Gruber

02:48

:= delays evaluation until execution

Ted Shifrin

Plus you need f[x_] @Axoren

Axoren

@AlexanderGruber oh my god, you're telling me this thing is lazy?

Alexander Gruber

@Axoren You have a choice, you can make it lazy

Kevin Driscoll

@MikeMiller $k$ isn't a frequency! It's a wavenumber. Dual to length.

Mike Miller

oh. yeah sure probably.

Ted Shifrin

02:50

We've morphed into Mathematica.SE

Alexander Gruber

Basically you decide when stuff evaluates. At first, you're not going to understand how it works, it takes a while to before you can start truly drinking the mathematica kool-aid on that level

Axoren

@AlexanderGruber You're telling me that I could have just said "f[x_]=" for a non-lazy first class value "f"?

Alexander Gruber

@Axoren x_ has a similar function to the # thing. It means that the x represents what you put in.

Axoren

@AlexanderGruber This is suddenly way to much power all at once.

I'm going to turn evil at this rate.

Kevin Driscoll

@Axoren Think of all the integral you can do!

Alexander Gruber

02:52

if you write f[x], you're defining the value of f for the symbol x. If you run f[x] = 1 and then you type f[x] it will give you 1, but if you type f[y], it's just going to give you back f[y].

Ted Shifrin

I think you're already evil, @Axoren.

Axoren

@TedShifrin That's what my local priest says.

Ted Shifrin

Well, I'm so evil I don't believe in priests or rabbis.

Alexander Gruber

and on the other hand, if you write f[x_] = 1 + x, then you'll get the thing you want to do, making a function which replaces the x's with what you put in the brackets.

Axoren

So if I showed you a priest, you'd tell me he doesn't exist?

Alexander Gruber

02:53

the := is a different issue. That's what makes it lazy or not lazy. (well, delayed or not delayed, anyway.)

Kevin Driscoll

@TedShifrin Percentage of Americans who vote for their ideal candidate if he's black? 92%

Ted Shifrin

Not in my personal world, @Axoren.

Kevin Driscoll

@Ted Percentage who would even if she's a woman 87%

@Ted percentage if he is an athiest.......47%

Ted Shifrin

I don't believe the 92%, @Kevin ... way too much racism in this country. I believe the atheist. Way too much religion, too.

Axoren

@TedShifrin It's the "white guilt" that makes it so high.

Kevin Driscoll

02:55

@Ted I think it's because its still socially acceptable to refuse to vote for an athiest, but not a black man

Axoren

Otherwise, he would have falsified the statistic lower.

Alexander Gruber

You're overthinking it, when you say ideal candidate you think of that as being separable from race/gender/religion, i.e. a candidate whose views the person agrees with

but it's not separable. Most people vote for the person.

Kevin Driscoll

@AlexanderGruber Ya I won;t vouch for the study design

Axoren

I think all candidates should be voted for in a Valentine Gameshow manner.

Ted Shifrin

I'm going to make a very snotty comment, @AlexG. I think what you just said is very much correlated with intelligence.

Axoren

02:57

You have no idea who they are, but you can ask questions about them and make your decisions from the other side of the wall.

Alexander Gruber

@TedShifrin so is "most people"

Kevin Driscoll

@Axoren There is a philosopher named John Rawls that says this is how we should determine the ideal public policies, except we are behind the 'wall' from ourselves!

Pedro Tamaroff

@TedShifrin I think using the Gutzmer formula to prove the maximum principle is pretty slick.

Probably the slickest proof out there.

Ted Shifrin

I know not whereof you speak, @Pedro.

Axoren

@KevinDriscoll Personally, I want a candidate who likes "Long walks on the beach."

Ted Shifrin

02:58

@Kevin: I wonder what the percentage is for gay ... :D

Pedro Tamaroff

@TedShifrin Perhaps you know it by the name of Parseval's formula?

Ted Shifrin

Mean value theorem, @Pedro?

Kevin Driscoll

@TedShifrin I think they asked and its noticably higher than athiest

@Pedro I love the Parseval/Plancherel theorem

Transcript for

$Mathematics$ Mathematics