The h Bar - 2018-01-19 (page 1 of 2)

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12:28 AM

if u use a transparent wallpaper for your computer will you be able to see behind the screen?

1:20 AM

@loocsieulb I needn't tell you, but blue is often the opposite of cool

It can burn you

1:33 AM

why

2:26 AM

is it because of blue stars

nerd

@loocsieulb I didn't say anything. It was your own nerdy mind that thought of that

It's always jarring why people randomly show Virasoro operators satisfy some algebra - apparently there's a reason - apparently, and this may be wrong, we note the Dirac constrained Hamiltonian theory forces the constraints to satisfy a Poisson bracket algebra, which is fine, that has it's own justification, but when you form the constrained Hamiltonian for the NG action and combine the constraints and impose the orthonormal gauge, you end up with the original constraints,

but then taking it's inverse Fourier transform (which is motivated as the inverse of what you did when imposing the constraints on the wave equation solutions) you end up with Virasoro operators as Hamiltonian constraints, and these have to satisfy some Poisson bracket algebra, which leads to the classical Virasoro algebra naturally.

Maybe I'm missing something, but when a book goes 'oh look, the $L_n$'s satisfy some magical algebra', it seems like it's out of nowhere, this is at least a reason to care about their algebra from first principles, thanks Scherk!

2 hours later…

4:17 AM

@SirCumference nah if i was a nerd i'd be technical and talk about blue on the blackbody spectrum :'(

but i'm not a nerd so i just said stars

4:30 AM

example of a dangerous art project back in the 2009 days

malware.wikia.com/wiki/Lose/Lose

4:49 AM

@X

oops

5:45 AM

@loocsieulb That's actually what I was referring to

Dammit, you have a point

Great

Goddard–Thorn theorem

In mathematics, and in particular, in the mathematical background of string theory, the Goddard–Thorn theorem (also called the no-ghost theorem) is a theorem describing properties of a functor that quantizes bosonic strings. It is named after Peter Goddard and Charles Thorn. The name "no-ghost theorem" stems from the fact that in the original statement of the theorem, the natural inner product induced on the output vector space is positive definite. Thus, there were no so-called ghosts, or vectors of negative norm. The name "no-ghost theorem" is also a word play on the no-go theorem of quantum...

The No-Ghost theorem explained in terms of functors

6:36 AM

@0celo7 how many hrs do u sleep

Anonymous

6:52 AM

@JohnRennie Morning! You there?

Anonymous

user image

@Blue Morning :-)

Anonymous

VS is showing me this ^

Anonymous

Do I need to buy the thing or just make a microsoft account?

You need a Microsoft online account to use VS, which is fair enough I suppose.

Luckily an MS online account is free.

Anonymous

6:53 AM

Ah, okhay. Looks reasonable

Anonymous

Thanks

account.microsoft.com/account

I think there's a link to create an account there.

Anonymous

Yup, found it

Bernardo Meurer

7:25 AM

user image

VICTORY

@JohnRennie My friend has now moved to Leeds :)

@BernardoMeurer Leeds is a nice city, but my goodness it's cold there in the winter!

Bernardo Meurer

@JohnRennie Morning!

And yeah, she's certain she will freeze

I hope she doesn't

Bernardo Meurer

7:41 AM

@ACuriousMind Long time no see!

@BernardoMeurer hey there

On my way to work

Bernardo Meurer

@ACuriousMind Pretty early for the CEO

How do you like work so far?

15 hours ago, by ACuriousMind

@JohnRennie I spent all day looking at compiler symbol tables, this job is great :D

Bernardo Meurer

Hehehehe

That is nice

I'm not going to be happy until you ask me for help with something

Please give me that pleasure

Given that most of my code will be in ABAP, I'm not sure you can help me

Bernardo Meurer

7:47 AM

Oh no

You're basically doing COBOL

How much are they paying you?!

Enough ;)

Besides, it has many modern features - just all the cruft is still there due to backwards compatibility

Bernardo Meurer

That's literally the worst possible configuration

Also, what do you define as modern even

It's what happens when not being backwards compatible would break millions of lines of code a large part of the business world depends on

Bernardo Meurer

And mostly what I find repugnant is the COBOL/SQL innerbred child of a syntax it has

No, I mean what's a "modern" feature

@BernardoMeurer objects, for example ;)

Bernardo Meurer

7:56 AM

Bah!

That's hardly modern!

And that's the worst feature!

OO must be unlearned

If its type system isn't turing complete I don't want it

Hah, I had a feeling you wouldn't like that :D

Bernardo Meurer

I don't like anything, it's not a hard feeling to have :P

There's also a terrible feature where keywords are not protected - you can call a variable 'if' if you like to :P

Bernardo Meurer

Hey, I like that!

Today I taught pointers to a guy

and I feel like he really got it

morning my dudes

Bernardo Meurer

8:00 AM

afterwards he wrote tic-tac-toe in C, using double and triple pointers (pointer to struct with double pointer) and it worked

I felt like such a masterful teacher

Ah, at least it has no annoying pointer arithmetic :P pointers exist but they're not as annoying as in C :P

The big flaw of C was using the same symbol for both the pointer of a value and the value of a pointer

it makes things a bit confusing

I'm not sure yet how I feel about there not being any arrays as such - just tables

Bernardo Meurer

@ACuriousMind Since when are pointers in C annoying? .-.

@Slereah Agreed

@ACuriousMind Wait what, there are only tables?

What is this language

Ada for its flaws used a clear syntax for pointers

Bernardo Meurer

8:03 AM

The guy today was confused about why int *p = calloc(5, sizeof(int)); set p->addr

but *p = 5 set addr<-p = 5

You know the worst part about C?

Undefined behaviour

Bernardo Meurer

::shivers::

I'm facing that issue right now actually

is your machine POSIX Sam?

It's the windows

Bernardo Meurer

Bah

@BernardoMeurer aye. If you want to have an array you use an unsorted table and access the table index as the array index

8:05 AM

IIRC shit like *d++ = *s++; is undefined in C

Bernardo Meurer

@ACuriousMind That literally makes me shake

Ah, I was going to ask you to test some code, I need someone with POSIX

@dmckee You're on a POSIX machine, right?

@BernardoMeurer why? A table is just an array with extra features.

worst part about undefined behaviour is that, from a standard point of view, if undefined behaviour occurs, the compiler can do what it wants

Bernardo Meurer

@JohnRennie Because I don't need those features so I don't want it

And that disturbs you so much you shake? :-)

Bernardo Meurer

8:06 AM

@Slereah From a standard POV undefined behavior could possibly impregnate you

@JohnRennie Yes. I am shaking right now as I think of it

@BernardoMeurer pretty much

It can have pretty grave consequences

Bernardo Meurer

@JohnRennie I think you forget how sensitive I am to this stuff

@Slereah Yes, that's true

@BernardoMeurer you'll find your skin gets thicker as you get older :-)

By 57 it will resemble rhinoceros hide.

Bernardo Meurer

I'm pretty old inside

Open Software does that

Use only OSX and you will remain a child forever

Bernardo Meurer

8:10 AM

Hehehehe

user image

I only use this computer

never any problem

Bernardo Meurer

Not ISO keyboard, I don't want it

Honestly

Can anyone try to figure out this C bug

I cannot anymore

it's been DAYS

WAIT

I GOT A CLUE NOW

what's the bug

@Slereah is flexing on us with his top tier computer

Bernardo Meurer

corrupted size vs. prev_size

@Slereah github.com/bemeurer/c-challenges

on 01

It's somewhere in this function

and it only happens when char *name that gets passed to it is not NULL

8:23 AM

does the compiler give you the line of error

Bernardo Meurer

Nope

I can't get it to trigger inside a debugger

or valgrind

-------------------------
SSN: (null)
DOB: 1953-09-07
Address: (null)
Name: Candelaria Stormes
Email: stormes-candelaria-53@yahoo.com
corrupted size vs. prev_size

It prints everything

(SSN and Address null b/c debugging, don't alter anything)

Is split_str a standard function?

Bernardo Meurer

@Slereah Nope, I wrote it

it's in there

Ah

Bernardo Meurer

split_str()

8:26 AM

"This happens when you are using memory which was not allocated to you or when you are using free() twice in a row on a pointer."

were you a naughty boy

Bernardo Meurer

Yes

I just don't know how yet

I would recommend the old trick

Comment lines until the error disappears

then you will know the line

Bernardo Meurer

gah-lee

On it

I

I think I got it

No

@Slereah Eh, can you take a look at something real quick

I found a really weird thing

sure

Bernardo Meurer

The computation for email_size is wrong

for some reason

But I don't see why

(I have use_dash and use_dob set to false statically)

8:39 AM

What should it be and what do you get

Bernardo Meurer

-------------------------
SSN: (null)
DOB: 1935-03-10
Address: (null)
Name: Marisa Seabrooks
Email: seabrooksmarisa@hotmail.com
---- name_count=2
---- email_size=17
---- email_size=27
-------------------------
SSN: (null)
DOB: 1997-05-07
Address: (null)
Name: Clarine Livingood
Email: clarinelivingood@yahoo.com
---- name_count=2
---- email_size=15
---- email_size=27
-------------------------
SSN: (null)
DOB: 1962-09-21
Address: (null)
Name: Heide Shimomura
Email: shimomuraheide@hotmail.com
---- name_count=2

Couple examples

Why is email_size there twice

Bernardo Meurer

The first one should be the length of both names tofether

the second one is total

with the provider

so for my email, for example

meurerbernardo@gmail.com

the first printf is the character count of meurerbernardo, and the second of the whole thing

Well the first name is 15 characters

and you get 17

first why do you initialize it at 1

Bernardo Meurer

I need space for the null terminating bit

So start at 1 already

8:42 AM

Print out the tokens, maybe?

check that the string is split correctly

Bernardo Meurer

Alright, let me try that

Eh, this is bizarre

Look at those examples

Why are the debug lines inside generate_email() getting printed after the email??

What is this magic

Woah

github.com/bemeurer/c-challenges/blob/master/01-name-generator/…

Look at where those printfs are

How is this

What

the error is gone

I used my mind powers

to remove the error

Bernardo Meurer

Aha!

New error

Now it explicitly gave me double free

But much less frequently

Oooooh

I am getting closer

Okay

1. Computing of email_size is wrong
2. Error is sporadic because only sometimes the computation errs low enough to cause shit, and that only happens when use_DOB and use_dash are enabled

user228700

~~Hello Darkness, my old friend!~~ Hello, everyone :-)

Bernardo Meurer

WHAT THE FUUUUUUUUUUUCK

THIS IS COMPLETE NONSENSE

-------------------------
SSN: 549302391
DOB: 1902-11-06
Address: Street Belfairs 6603
Name: Clare Whitmire
Email: whitmire-clare@gmail.com
---- name_count=2
---- token[0]=Tonita
---- token[1]=Gertner
---- names size=14
---- strlen(provider)=10
---- email_size=25
-------------------------
SSN: 061565537
DOB: 1958-05-17
Address: Lane Penpool 9120
Name: Tonita Gertner
Email: gertner-tonita@gmail.com
---- name_count=2
---- token[0]=Tami
---- token[1]=Gau
---- names size=8
---- strlen(provider)=10
---- email_size=19

@Slereah Can you give me any good reason why the debug info would be out of order?

This makes no sense

I am running this in a bash script with a while loop

8:56 AM

Unless you're running some threads no idea

Bernardo Meurer

Woah

My terminal emulator is retarded!

I found a bug

in my terminal emulator

user228700

@JohnR: I've downloaded the movie, BTW, you can take it off now :-) Thanks a bunch!

Bernardo Meurer

Maybe it's tmux's fault

@Kaumudi.H aha, you're home! :-)

Did you get both films?

Bernardo Meurer

8:58 AM

@JohnRennie I am dyign

Hell yeah

user228700

@JohnRennie Both?

user228700

@BernardoMeurer Yes, poor man unable to spell, even...

@Kaumudi.H End of the Tour and Paterson?

user228700

@JohnRennie Ah, didn't I tell you? I was able to download the former early in the morning one day, from hostel!

user228700

8:59 AM

Watched it, too!

@Kaumudi.H Cool :-) As good as you thought?

user228700

No, but good enough :-)

user228700

Yet to watch Paterson though. I might, today.

I went to see The Last Jedi on Wednesday. And I thoroughly enjoyed it :-)

user228700

Ah, yes, I saw your post on Fb! Cool! :-)

user228700

9:02 AM

I watched the very first film (4th) and didn't feel motivated enough to continue. Oh, well.

user228700

Yo @Balarka: How is you?

good

user228700

Cool :-) Exams approaching?

yes

user228700

@BalarkaSen Hmm. Destressing by watching whatever this is?

9:04 AM

i am not stressed

it just appeared on my recommendations

user228700

@BalarkaSen Oh, that's good, then :-)

user228700

Ah, lol, I see.

@0celo7 My copy of Milnor's red book arrived yesterday. Might end up reading more Morse theory

Bernardo Meurer

My grandmother thinks I have a woman problem

@BernardoMeurer the fact that you don't have any?

Bernardo Meurer

9:10 AM

Exactly

4

Q: How can I restore power after a switch was shorted with scissors?

Ok, so I'm a 15 year old kid and my parents werent home, my house is under construction and I wanted to see what would happen if I put scissors to my light switches, so I took the pair of scissors and I put it to the light switch on the hot side and It sparked really big and really loud, and now ...

good post

That has to be a troll

Bernardo Meurer

Lol

Paul Logan?

Jesus

Bernardo Meurer

Oh wow, lol

I hadn't even noticed

@BalarkaSen Are you in High School or Middle School?

9:21 AM

The former

Bernardo Meurer

Meh, then you probably can't help me

What did you need help with

Bernardo Meurer

I wanted to ask if there are Indian Jake Paulers and Logan Paulers like here in the US the kids are nuts

I don't think they are that famous here, no

Bernardo Meurer

Sigh

You guys are better off

10:00 AM

@BalarkaSen I thought you said you were in high school?

That's what former means...

the first of the two

Bernardo Meurer

@SirCumference What is wrong with you

Wow I'm blind

@BernardoMeurer Well it's 5:00am here...

Bernardo Meurer

You don't believe I'm Ryan's brother

you don't believe Balarka is in High school

Ryan who?

Bernardo Meurer

10:04 AM

you don't believe former is the first of the two

@Sir your insomnia is really taking a toll on you

Bernardo Meurer

@0celo7

@BalarkaSen I feel pretty ok

Bernardo Meurer

is my brother

@BernardoMeurer I thought his name was Rick?

Bernardo Meurer

10:05 AM

Lol

What

@0celo7 are you Rick Astley?

ryan's gonna rickroll us

Welp, how are you guys

trying to understand some math

@BalarkaSen I still am amazed how much you know as a high schooler

Like jeez

Bernardo Meurer

I'm trying to understand how the fuck OoO works

10:08 AM

OoO?

OoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoOoO?

Bernardo Meurer

Out of Order CPUs

@Sir Really, what counts more than knowledge is the skill to apply it

Bernardo Meurer

In particular the BOOMv2 design in RISCV

It's the latter I am really working on

(And not very good at)

@BalarkaSen Ah, so you're not interested in pure math?

Or at least, do you find math interesting in itself?

10:09 AM

I am. By applying I meant applying whatever you know to actually prove something

Bernardo Meurer

Solve that shitty list of exercises, lol

Oh yeah good call

I should

Bernardo Meurer

Who wins

prove math

all of it

Maybe I should just take Analysis, it seems interesting

Bernardo Meurer

10:11 AM

A 19 year old with years of math study, good nutrition, and the entire internet

one mathy boii

@BernardoMeurer Wait blood brother or friend brother?

Bernardo Meurer

@SirCumference Blood brother goddamit

we are brothers

he means they're both black

Bernardo Meurer

Christmas together

I call his sister sister

@Slereah like this?

10:12 AM

@BernardoMeurer Biological blood or figurative blood?

Bernardo Meurer

@SirCumference I give up

@Sir They're related biologically, or so they claim

@BalarkaSen No, more like

user image

@BalarkaSen everyone is related biologically

3

That doesn't mean much

I give up too

Oh no

Lee brings up the functors

10:13 AM

@BernardoMeurer I see, so how are your children

Oct 8 '16 at 3:49, by 0celo7

@SirCumference He is married with children.

Shoo shoo categorists

Quit trying to fool a sleep deprived man, shame

Bernardo Meurer

At the time that message was sent

it was true that I was married

However I do not have children AFAIK

However it isn't unlikely that they exist

I thought you said you were 17?

So?

10:15 AM

Maybe it's one of those shotgun weddings I hear are big in the US

You can live happy family life at 17

Bernardo Meurer

I was 18 when I married

Welp, California is a hypothetical realm

Bernardo Meurer

I married a Slovenian who was friends with Slavoj Zizek :)

I was in Lisbon, not California, when this happened

@BernardoMeurer Ah, would you like to see a magic trick?

Ok...then @BernardoMeurer, would you like to see one?

10:38 AM

"It would perhaps be more appropriate to refer to the frame bundle of a vector bundle $\xi = (E, \pi, M, V)$ as $F(\xi)$ since the notation $F(E)$ is inconsistent with the notation $F(M)$ above. After all, $E$ is itself a manifold. Despite this we will continue with the dangerous notation."

Living on the edge

1 hour later…

Captain Bohemian

11:44 AM

what is ''coarse-grained'' information?

without going into details?

Captain Bohemian

so coarse-grained means rough? the term coarse-grained appears frequently in articles regarding renormalization group and I keep not quite understanding what it means.

12:05 PM

what's the context

12:21 PM

"We can say that a section $s\in \Gamma(E)$ is horizontal (i.e. constant) along a curve $c : I \to M$ if $Ts \cdot \dot c(t)$ has a vertical projection of zero for all $t$"

what does $Ts \cdot \dot c(t)$ mean

1 hour later…

1:34 PM

@Slereah think about what Ts is

the tangent bundle of every point in $s$?

I don't recall seeing the notation $Ts$ for a section

it's the differential

What?

it's the differential of $s$

Which one, just $ds$?

Or $\operatorname d s$, if you prefer

1:43 PM

@Slereah yes, I presume that's what he means

the point being then that $Ts\cdot\dot c\in TE$

Odd notation for it

What is the $\cdot$ supposed to be, just an inner product?

The canonical one?

action of a linear operator

Wait no, that wouldn't be part of $TE$

the french do $Ts.\dot c$

Odd notation

Action of a linear operator is usually nothing

1:45 PM

completely standard and common notation

What would it be in index notation

if there is an equivalent

contraction

So... $(ds)^a_b u^b$?

yes

Aight

thx

What is the definition of $Ts$ exactly, is it a section of $\Gamma(TE)$ such that $\pi(Ts) = s$?

He doesn't seem to introduce the notation

seems to be the first use of Ts in the book

Ahah

It does seem to appear in the differential form section

As $T_p f \cdot v_1$

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Jan '1819

The h Bar

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