The h Bar

Bernard Meurer

22:00

Sigh

0celo7

I'll help you for real when I'm done transcribing my algebra notes

Bernard Meurer

Alrighty

0celo7

@ACuriousMind $X=\{x|P(x)\}$ or $X=\{x:P(x)\}$?

I need to pick one for the rest of my life at this very moment

ACuriousMind

@0celo7 $\mid$ (\mid, not \vert)

0celo7

is \mid different than \vert?

ACuriousMind

22:04

$\{x\mid P(x)\}$ vs. $\{x\vert P(x)\}$.

0celo7

whoa

that's amazing

@BernardMeurer btw the bank lagrangian is your actual money - potential money

Bernard Meurer

22:20

@0celo7 the what?

0celo7

Do you not know any analytical mechanics?

Ok, algebra notes transcribed

I'll hold off on PDE and Lit to help you

@BernardMeurer Ok, so the monthly balance is fixed?

Do you know the equation for interest?

Bernard Meurer

@0celo7 do you happen to know Python? I did a brute force solution that might help explain what I'm trying to achieve

0celo7

No, but I plan to learn it over the summer.

Bernard Meurer

But basically having a fixed annual interest $J$ that is applied at the end of every month with a value of $\frac{J}{12}$ and a debt $B$ how can I calculate the minimum value $P$ to be payed monthly so to get the debt over in 12 months

0celo7

oh great the interest gets compounded differently each time

bleh

Bernard Meurer

22:27

Yep

0celo7

gl :)

Bernard Meurer

and $P$ is a fixed value

0celo7

this is a really nasty problem

can we go for like two payments first

Bernard Meurer

My brute force solution is rustling my jimmies, I want an elegant solving strategy.

Sure, let's go a little at a time

0celo7

Alright, so $P$ is the principal and $j$ is some percent, right?

Like at $t=1/2$ (let $t=1$ be one year), then you all of a sudden have to pay $P+\tfrac{1}{2}jP$, right?

Bernard Meurer

22:30

Yes let's use the example values $J = 0.2 (20\%)$ and $B=3329$

0celo7

dude I am not using numbers

wtf is B now

Bernard Meurer

The debt hahaha

0celo7

can we use standard symbols?

Bernard Meurer

Sure, define the symbols

0celo7

$A$ is the thing you actually have to pay. $P$ is the principal, i.e. debt w/o interest. $r$ is the interest rate...

Uh, how often is this being compounded?

Bernard Meurer

22:32

Sounds good to me

0celo7

Bernard Meurer

As in how often the payment is done?

0celo7

Uhhhhh

I hated doing this in school

I'm not sure your problem can be solved elegantly.

Bernard Meurer

Yeah that's what I fear

@ACuriousMind any ideas?

0celo7

Can you convert your Python code into Java/Matlab?

Or draw a little diagram explaining it?

Bernard Meurer

22:35

Can you paste multiline code here?

The code is very easy, it'll be just like reading english

0celo7

Try it out

ACuriousMind

@BernardMeurer I don't do finance math

FenderLesPaul

@GBeau no emails for me yet

ACuriousMind

(Also, I'm not even sure I understand all of the English terms right)

0celo7

@ACuriousMind You sure you can't turn it into a statement about projective varieties on a moduli space?

@ACuriousMind Same here.

Bernard Meurer

22:37

balance = 3329
annualInterestRate = 0.2
pay = 0
nbalance = balance
while nbalance > 0:
    nbalance = balance
    pay += 10
    for month in range(12):
        nbalance -= pay
        nbalance *= (1 + (annualInterestRate / 12))
print "Lowest Payment:", pay

Ta-da!

ACuriousMind

@0celo7 No. But it's just a boring problem. If I had to solve it for some practical purpose, I'd do it, but I'm not spending brain cells on that for fun

@0celo7 Heh

0celo7

5 mins ago, by 0celo7

Uhhhhh

^Me realizing I have no clue what any of this means :D

Bernard Meurer

@ACuriousMind I don't either, which is why this thing is sucking my soul

0celo7

@BernardMeurer pay += 10 ?

I know that's pay = pay + 10, but what does that do

Bernard Meurer

It's another part of the problem that I didn't disclose, the payment must be a multiple of 10

god knows why

0celo7

22:39

...what

Bernard Meurer

even if that means you'll pay more than you should at the end of the year

0celo7

oh ffs

Well that changes everything

ACuriousMind

@BernardMeurer You only have figured out how to forge ten dollar bills, duh.

0celo7

You now have a gauge theory on your hands, there's a constraint

amazon.com/Quantization-Gauge-Systems-Marc-Henneaux/dp/…

The solution is in ^

Bernard Meurer

You can just calculate $P$ normally and do a $\lceil{\frac{P}{10}} 10$

0celo7

22:41

@ACuriousMind tfw his teacher is getting him to run a counterfeiting operation

@BernardMeurer just give up

Bernard Meurer

::cries::

ACuriousMind

@0celo7 Counterfeiting is probably a more valuable skill in the real world than anything on the "real" curriculum

0celo7

@ACuriousMind ::proves statement on Fibonacci numbers::

agreed

Bernard Meurer

Can I ask this on math exchange even?

0celo7

no

programming golf

Bernard Meurer

22:46

But I'm honestly more curious about turning it into a discrete equation

prog people will just tell me to use bisection

0celo7

@ACuriousMind How do I write "p does not divide q"

$p\not\vert q$?

GBeau

@FenderLesPaul ditto

FenderLesPaul

@GBeau I just can't wait for these two weeks to be over

GBeau

@0celo7 it's \nmid (and \mid for divides)

so $p\nmid q$

DanielSank

Hey @BernardMeurer.

0celo7

22:56

@GBeau Ah, thanks.

GBeau

@FenderLesPaul I feel like I'm going to get a lot of them in February still

FenderLesPaul

I think mine (if I get in) will be late Jan

0celo7

@DanielSank How come the rest of us don't get greetings?

FenderLesPaul

around the 25th-30th

DanielSank

@0celo7 Hi.

^ Happy?

Greetings @ACuriousMind.

0celo7

22:57

No.

FenderLesPaul

although I applied to umich and haven't gotten any emails from umich

0celo7

That's like when a child does not say "please"

FenderLesPaul

which doesn't bode well for me

0celo7

It doesn't matter if they have to be reminded

They already ruined someone's day

@FenderLesPaul hey that's where my research prof did his postdoc

GBeau

@FenderLesPaul A lot of schools have no obvious historical patterns in the order of acceptances; I have some guesses, though

FenderLesPaul

22:59

@0celo7 ain't that a thang

0celo7

he also did his BS+PhD at @ACuriousMind's school

GBeau

@FenderLesPaul There could be additional delays (O(days)) debating who gets fellowships, or waiting for responses from specific departments

that would cause some otherwise weird orders in sending out acceptance emails

FenderLesPaul

@GBeau I suppose but apparently some people have gotten emails from umich and I haven't yet so I'm bummed :(

GBeau

@FenderLesPaul same for two of the schools I applied to

FenderLesPaul

umich is hard to get into but if I can't get in there then there's no chance of me getting into uchicago

0celo7

23:01

unless Wald remembers you

You have to get into Chicago, @FenderLesPaul

FenderLesPaul

he isn't on their admissions committee :(

0celo7

He might have a friend on there

FenderLesPaul

I checked

0celo7

WE NEED TO KNOW THE PROOF OF THEOREM 8.1.1

FenderLesPaul

haha

0celo7

23:02

Ahem.

DanielSank

@0celo7 why do physicists call $dx/d\mu$ a tensor?

Maybe there are subscripts.

0celo7

@DanielSank What is that?

DanielSank

Does that question make sense?

0celo7

No.

DanielSank

k

0celo7

23:03

What is $dx$?

Do you mean the one-form?

Or is $dx/d\mu$ a derivative?

DanielSank

I think maybe it's a form in some broke-ass notation.

0celo7

If $dx$ is the one-form, I can give you the answer.

DanielSank

go for it

0celo7

And it's not physicists, it's math people too.

FenderLesPaul

although uchicago did let me update my application to include my undergrad research award

which may help

0celo7

23:05

@DanielSank So you know that the partial derivatives $\partial_\mu$ form a basis of the tangent space in some chart, right?

FenderLesPaul

no point speculating at this point I suppose :p

DanielSank

@0celo7 Let's make that really clear because I don't quite understand what that means.

user54412

@FenderLesPaul Your worrying has managed to make me anxious about grad school apps.

0celo7

@DanielSank Ok, how do you want to define "vector"

DanielSank

^ That's the key, isn't it?

I have some manifold, yeah?

0celo7

23:06

Well, I can show you the equivalence :)

DanielSank

I can chartify it if I want.

0celo7

You just have to tell me what you're willing to take as a "vector"

@DanielSank A differentiable (even topological) manifold has a (set of) chart(s) by definition.

FenderLesPaul

@ChrisWhite :(

my entire future is on the line!

0celo7

you can always become a hooker if all else fails

FenderLesPaul

I suppose I could do that

DanielSank

23:08

@0celo7 Right, I know.

I'm trying to remember why vectors even come up.

FenderLesPaul

I'd only be successful in west hollywood though

0celo7

Because I'm trying to define dx for you!

DanielSank

@0celo7 Well, let's try to keep things motivated here.

0celo7

I am.

DanielSank

I have a manifold $M$ and presumably a function $f: M \rightarrow \mathbb{R}$.

0celo7

23:09

Sure

DanielSank

It's kind of clear in my mind what it means to integrate $f$ over $M$.

0celo7

The tangent vectors are the set of derivations of germs of functions

DanielSank

@0celo7 germs?

0celo7

@DanielSank Uh, if two functions agree in some nbhd around some point, we have an equivalence relation, the equivalence class is called a germ

DanielSank

@0celo7 Weird. never heard of that

0celo7

23:11

(you can ignore it)

DanielSank

::ignores it::

0celo7

Only the most pedantic texts talk about germs.

GBeau

@FenderLesPaul At some point no news is bad news

DanielSank

@0celo7 Ah yes... we want some notion of a derivative.

Let's see here... I think we want a thing where if I feed it a direction it produces the change of $f$ as I move in that direction. Right?

0celo7

@DanielSank So if $f,g$ are (smooth) functions, then a derivation at point $p$ is defined by $X_p(fg)=X_p(f)g(p)+f(p)X_p(g)$

$X_p$ is ofc linear

DanielSank

23:13

@0celo7 Yes yes, but the real reason we want this thing is that we can use it to produce directional derivatives, right?

Well, and other stuff, I suppose.

0celo7

@DanielSank Yes, and directional derivatives satisfy the Leibnitz rule

What I just gave is the Leibnitz rule

FenderLesPaul

@GBeau right

0celo7

@DanielSank Wanna move this to another room?

DanielSank

@0celo7 yeah.

I'll make.

oh ok, you make

0celo7

too late

FenderLesPaul

23:15

I just don't know when that point comes

GBeau

@FenderLesPaul Emotionally? every other hour. Practically? Late January-Late February depending on the school

ACuriousMind

@DanielSank Greetings

TanMath

hello all!

Emilio Pisanty

whoooooooo

0

A: Community Promotion Ads - 2016

man, look at that sexy ad

cf. this unfortunate creation :-(

Bernard Meurer

23:32

Hey @DanielSank!

ACuriousMind

@EmilioPisanty That looks decidedly nicer!

0celo7

@BernardMeurer he's busy

FenderLesPaul

@GBeau emotionally sounds about right haha

Bernard Meurer

@0celo7 Can I leave my message after the beep?

0celo7

@BernardMeurer nope

Bernard Meurer

23:36

@0celo7 Darn it.

ACuriousMind

@BernardMeurer You can always leave your message

Jun 17 '15 at 6:43, by DanielSank

I regard online chat as an asynchronous communication protocol :-)

0celo7

@ACuriousMind b*tch I'm his secretary not you!

TanMath

^

ACuriousMind

@0celo7 You are?

0celo7

@ACuriousMind wtf ofc I am

ACuriousMind

23:39

I see.

I wonder if he knows.

0celo7

he does, no need to bother him with it

ACuriousMind

@0celo7 Ah, but Vertrauen ist gut, Kontrolle ist besser

0celo7

@ACuriousMind Is that like "trust but verify"

(in theme)

(I can translate it myself)

ACuriousMind

@0celo7 Yes (unless trust but verify means something completely different from what it sounds like :P )

I read that.

0celo7

Good.

It was an application of the theorem.

ACuriousMind

23:44

I have no idea what you're talking about

0celo7

@ACuriousMind You just can't handle my mind...it works on a higher plane

ACuriousMind

...probably in dimensions to small to see, eh? :P

dmckee

@ACuriousMind He know everything we do, because we're all his sockpuppets. Don't you remember?

ACuriousMind

@dmckee I have chosen to suppress any thoughts about my depressing lack of individuality

0celo7

@ACuriousMind you didn't like that joke when I made it about your man bits and it's not funny about my mind either :(

ACuriousMind

23:50

@0celo7 It's funny cuz it's true

0celo7

@ACuriousMind it's true both ways

ACuriousMind

What would a "one-way truth" be?

GBeau

@FenderLesPaul Tomorrow is a work day D;

0celo7

@ACuriousMind what?

this is why I don't want the children homeschooled

ACuriousMind

I don't want that either

0celo7

23:56

good

now you pay for the private school

ACuriousMind

No, we move to a country with proper public education, obviously.

0celo7

And who will pay for the move?

I have my book club, etc. here as well. I don't want to move!

no_choice99

which country

is good for edu

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