Mathematics - 2015-03-04 (page 5 of 5)

I won't go to a cinema again until I start earning money.

Pedro Tamaroff

There's the book, in the movie.

Some movies start from books and some books start from movies.

Ah, lol. I haven't seen it either. My sister watched it a long time ago, but I didn't watch with her. She seemed to like it, and we have somewhat similar taste, so I imagine I might too.

No spoilers, @Pedro.

10:04 PM

Anyone here uses Ubuntu?

I think I'll watch Adaptation tonight @Mike. It looks like my kind of movie.

Let me know if you give it good reviews, @Alex. I love Kaufman.

I am waiting for Debian 8 to be released this year.

Will do, @Mike. :) What authors do you like?

I don't read any fiction.

10:11 PM

have you tried?

No interest.

you may like it

True.

:-)

Isaac Asimov is probably my favorite author

10:19 PM

Asimov described Carl Sagan as one of only two people he ever met whose intellect surpassed his own. The other, he claimed, was the computer scientist and artificial intelligence expert Marvin Minsky.[50]

Hello @TedShifrin

heya @teadawg

It's been a while since I've read anything new, @AlexWertheim. I used to be a big fan of Joyce, Pynchon, Gaddis, DFW, Murakami, Beckett...

My county was upgraded to a Winter Storm Warning at around noon

Now I'm trying to get into reading film crit in my spare time but haven't really started.

10:20 PM

Murakami is wonderful. What have you read of his?

Kafka on the shore, 1Q84. I have a copy of the wind-up bird chronicle I havrnt read yet.

Hello!!

I am looking at an exercise that asks to describe the surface r=constant, θ=constant and z=constant in the cylindrical coordinate system.

What does this mean?? What am I supposed to do??

@teadawg: I take it that means a downgrade?

Both excellent. You might like "The Elephant Vanishes", a collection of short stories he wrote.

hi @AlexW

10:22 PM

Hello, @Ted! :)

@skull: Minsky taught at MIT.

@TedShifrin No, it was a Winter Weather Advisory earlier. Warning>Watch>Advisory

right, @teadawg: I meant an emotional downgrade.

I guess so, since I most likely won't be able to go anywhere tomorrow

no, @MaryStar, they mean three different sorts of surfaces.

More math to do, @teadawg :D

10:24 PM

Probably, @AlexW. I've got three books on my table I haven't read yet: "Wittgenstein's mistress", "Forget Foucault", and "Zona" (a book about the movie I mentioned, Stalker.)

One thing I'm looking forward to in retirement is reading a lot more ...

What does this mean to describe them?? @TedShifrin

I think I should take a break from doing mathematics tomorrow, I've been working on this one problem for the past few weeks and I'm getting nowhere

Common words, @MaryStar, like sphere, cylinder, plane, cone, ...

I'm 20 pages into one and they've been there for a month or so. :P

10:24 PM

or you could do something different, @teadawg :P

@TedShifrin it's an interesting Wikipedia page :-)

Looks interesting. :) Very much in keeping with the surrealism theme.

Heh, that's usually how reading goes. I tend to enjoy short stories for that very reason. I don't know whether it's a matter of attention span or what, but I think I get too easily lost in longer novels.

I've run the numbers almost 50 times, the result checks out. The main issue is in proving it...

That, or Hemingway. If the writing is terse enough, I feel less bogged down.

@AlexW ... I never could learn to make it through Faulkner. I tried.

10:27 PM

I've never been a Faulkner man myself, @Ted. "As I Lay Dying" was a chore for me to read.

I took a course on Fitzgerald, Hemingway, and Faulkner in college, @AlexW.

Shame, because "The Sound and the Fury" is supposed to be one of the great pieces of American literature.

That sounds like 2/3 of a good course, @Ted. :)

I took mostly French literature, however.

ɧɿρρԹʅȝՇԵՐՎԾՌ

:D

Who knew ... I went to MIT.

10:28 PM

Proust, Camus, the like?

Flaubert

lots more than that, yes ... seven or eight courses

ɧɿρρԹʅȝՇԵՐՎԾՌ

Le rose et le vert

some poetry (Baudelaire, Nerval), theater, novels, different epoques ...

Wow. No wonder your French is so great :)

@Hippa won't say it's so great ... and he'd be right.

Ramanewbie

10:29 PM

hi le @ted

Hemingway is wonderful. Very terse in a beautiful way. I love it when an author chooses their words carefully.

as another example see cormac mccarthy...

Ramanewbie

front le @ɧɿρρԹ

Agreed x 1000, @MikeM.

Q: Euler's method - Order of accuracy

Could you take a look at my question?

1

Theorem Let $f \in C([a,b] \times \mathbb{R})$ a function that satisfies the Lipschitz condition and let $y \in C^2[a,b]$ the solution of the ODE $\left\{\begin{matrix} y'=f(t,y(t)) &, a \leq t \leq b \\ y(a)=y_0 & \end{matrix}\right.$. If $y^0, y^1, \dots, y^N$ are the approximations of Eule...

even if @Mike don't choose their words so carefully :P

hi @Ramanewb

10:31 PM

I also found as I lay dying tedious, but appreciated the challenge of the sound and the fury. I don't think you'd like it much better, though, if you didn't like as I lay dying.

"Roses for emily" is a good short story by Faulkner; he doesn't have time to become dull.

I tried to read Absalom Absalom two or three times and gave up.

Oh, I forgot to say Borges is fantastic.

Probably not. I don't have much of an appreciation for stream of consciousness writing.

You'd hate Joyce. :P

Yeah, I think so too. I've briefly forayed into "Ulysses" but couldn't stomach it. I know it's supposed to be a great work, full of many deep allusions, but I didn't much enjoy it.

10:35 PM

Fully understand that. One of my favorites, but it's folly to try to force someone to enjoy it.

The greatest thing I've ever read was a book of short stories called "You Do Understand." I think you would enjoy it a lot, especially if you like authors who choose their words very carefully. :)

Slovenian literature series?

skull will tell us that this has turned into the English.SE chat room

That's the one.

;D

10:36 PM

Hey, it's better than the non-math we usually talk about in here, @Ted

hard to argue with that, @Mike ... although food isn't bad :P

I'm in the process of throwing out all my college literature term-papers .... English and French.

@AlexWertheim: If you have a chance, read this. One of my favorite Borges stories.

@TedShifrin The cylindrical coordinates are $(r, \theta , z)$, that are defined by $x=r \cos \theta , y=r \sin \theta , z=z$

$r=\sqrt{x^2+y^2}, z=z , \theta=\arctan (\frac{y}{x} )$

r=constant=c: $c=\sqrt{x^2+y^2} \Rightarrow x^2+y^2=c^2$ Is this a circle??

θ=constant=k: What can we say at this case??

z=constant=m: How can we use this to find the surface??

I will read it right now. :)

@MaryStar: Truly, you need to figure this out for yourself.

No, it's not a circle. What about $z$?

10:40 PM

Hello @quid!!! Are you familiar with Numerical Analysis?

Is it a cylinder with radius $r=c$?? @TedShifrin

Yes, @MaryStar.

Hello @evinda Sorry no, rather not. I knew only little about it when I was a student and it went down from there.

A ok @quid No problem :)

And how could we justify it?? @TedShifrin

10:43 PM

You seem to study many different subjects @evinda

@quid Yes, I do.. I have 5 different subjects this semester..

I hope everything will work out well.

@MaryStar: Think about what the equation $x=2$ or $x^2+y^2=4$ means in $\Bbb R^3$.

@quid I hope so too.. :) Do you teach every day?

No. Normally twice a week.

10:46 PM

Aha! @quid

Some of us teach 4 or 5 days a week. ...

@TedShifrin So you teach more than one subject, right? @TedShifrin

At $x=2$ it means that $y=0$ and $z=0$.

At $x^2+y^2=4$ it means that $z=0$.

Is this correct?? @TedShifrin

No, @MaryStar, you just added extra equations. Who gave you permission to do so?

I usually teach two classes, @evinda.

None after two more months.

@TedShifrin one likely should also take into account how many hours one teaches on the days one teaches.

10:48 PM

@TedShifrin What do you teach now?

Yes, @quid ... I wasn't claiming any superiority :P I teach my differential geometry class 2 days a week, but generally believe that students do better with math 3 or 4 days a week.

@evinda: Differential geometry and "my" multivariable math (integrated multivariable calculus/linear algebra/theory) course.

Aha... @TedShifrin

@TedShifrin Well, one could also have it as a point of pride to have a low teaching load. :-) For the spreading, I rather agree. But it is not really up to me as everything runs in a globally fixed schedule. So, I get assigned my slot and that's that.

I would be surprised if people who take pride in a low teaching load would waste time here.

@BalarkaSen I know, I became fairly sure i was overcounting some when it resulted in a negative number for $n=4$ haha, but I haven't had time to think about it again

10:54 PM

@Ted: Is UGA particularly well-known for its teaching rigors?

no, @Mike, our department used to value it.

I take "used to" as a statement of sadness.

Values are changing globally :(

$x=2$ a surface that is paralle ro the yz plane, right?? @TedShifrin

yes @MaryStar :P

10:57 PM

Beautiful, @Mike. (Sorry, I am quite a slow reader)

No apologies necessary; I reread it and finished just a few minutes before you.

Reading too fast misses the ever-present subtleties...

What can we say about $x^2+y^2=4$ ?? @TedShifrin

You figure it out, @MaryStar.

For sure. This is the first time I've read Borges. I'll have to read more. Any recommendations?

I have a wonderful short story book of his; I think it's called "Collected Fictions"

10:59 PM

@AlexWertheim What have you read from Borges? There are a lot of works from him

It is a circle at the plane $z=0$, or not?? @TedShifrin

@Alessandro: only what Mike just sent me, "The Garden of Forking Paths".

Not.

Another pleasant story is "Tlon, Uqbar, Orbis Teris", or something similar. I've probably misspelled it.

I'll look into both. Great stuff.

11:01 PM

That story should be in collected fictions somewhere.

@Alex I second @MikeMiller's suggestion, "the library of babel" is another of the very known short stories that I liked a lot

It's a tube, ya?

Who knew MSE chat could be such a nice source of new reading material? :)

Hello @Alessandro!!!

Agreed, @Alessandro

11:02 PM

@Alessandro !!

@AlexWertheim If I remember correctly there is a collection called "The Aleph" with both the short stories we just named and many more (but maybe "The Aleph" is a story and the collection has another name, I should look it up)

Good evening @evinda @TedShifrin

Why isn't it a circle at the plane xy?? @TedShifrin

So many people!

@Alessandro How are you? :)

@MaryStar there's no restriction on what $z$ can be, is there?

11:04 PM

It's a short story, @Alessandro, but I wouldn't be surprised if there was also a collection with that name

One fewer now. I've got to run and catch my bus. Later all!

Bye!

Fine, thanks @evinda, what about you?

Oh, I thought that since there is no $z$, we suppose that $z=0$... @TedShifrin

@MikeMiller It is also a collection, but apparently it doesn't contain neither "the library of babel" nor "tlon uqbar orbis tertius" so my memory was half correct at most

11:07 PM

@Alessandro Fine, thanks.

@MaryStar If there is no restriction on z, z can be anything, so you get a cylinder.

Wow, that killed the conversation, lol.

random facts since we're already talking about books, in "the name of the rose" the blind librarian is called "Jorge da Burgos" as an homage to Borges

I prefer to call it a tube, since cylinder gives the image of finite extension

@Alessandro Was gibt es so neues bei dir?

A tube? Interesting. Never heard of.

@AlexWertheim If the bus is running and you are running, you can't catch it.

11:12 PM

@evinda nichts besonderes :( und bei dir?

Q: The sum of orbit size of some element over the image of group "polynomial"

was the plane the tangent plane to the tube by design?

Paul Plummer

3

$\DeclareMathOperator{\orb}{orb}$ Say I have a group "polynomial", $p$, on $S_n$, that is $p(x)=a_1 x^{\epsilon_1}...a_n x^{\epsilon_n}$ for all $x \in S_n$, fixed $a_i \in S_n$ and fixed $\epsilon_i \in \mathbb{Z}$. Let $p S_n$ be the image of the polynomial. Generally, I am looking for $$ X(S_n...

combinatorics group-theory reference-request symmetric-groups group-actions

@Alessandro Bei mir auch nicht... Das neue Semester hat vor 3 Wochen begonnen..

Ahaa... I see... @ABeautifulMind

@evinda Welche Fächer studierst du jetzt?

11:16 PM

@MaryStar I see that you are a star, just like me, lol.

Warum sind wir Deutsch sprechen?

@Alessandro Kryptologie, Komplexitätstheorie, Numerische Llösung von differentialgleichungen, Methoden der Angewandte Mathematik, Partielle Differentialgleichungen..

@evinda sie sehen interessant aus, besonders Kryptologie

@evinda can you use aussehen in this way or is it only for physical appearance?

@Alessandro You can use it in this way!

@evinda danke :D jetzt gehe ich ins Bett, gute Nacht!

11:26 PM

@Alessandro Gute Nacht!!! :)

what about when θ=constant?? What can we say at this case?? @TedShifrin @ABeautifulMind

11:50 PM

@MaryStar What is the context?

1 hour ago, by Mary Star

@TedShifrin The cylindrical coordinates are $(r, \theta , z)$, that are defined by $x=r \cos \theta , y=r \sin \theta , z=z$

$r=\sqrt{x^2+y^2}, z=z , \theta=\arctan (\frac{y}{x} )$

r=constant=c: $c=\sqrt{x^2+y^2} \Rightarrow x^2+y^2=c^2$ Is this a circle??

θ=constant=k: What can we say at this case??

z=constant=m: How can we use this to find the surface??

Ah, I think you should figure it out yourself. =)

I have to describe the surface θ=constant in the cylindrical coordinate system.

The cylindrical coordinates are $(r, \theta , z)$, that are defined by $x=r \cos \theta , y=r \sin \theta , z=z$

We have that
$r=\sqrt{x^2+y^2}, z=z , \theta=\arctan (\frac{y}{x} )$

But how can we find the surface?? @ABeautifulMind

If theta is contant, and r and z can be anything, then...

Put in different values of r and z and see what you get, then combine them all...

Also 1 question should have 1 question mark :-)

11:56 PM

@infinitesimal LOL.

I am leaving this chat now, bye.

Adios, amigo