The h Bar

Mew

09:00

huh

Swapnil Das

Hmm..

Topology is damn hard for me :(

kevin Tah N.

09:40

hey

it obviously takes some time to study

It is funny you say that. I actually came here because I have some clue how to construct hoschild homology but can't figure its significance. What about topology is it saying, the simple construction is somewhat a bit too algebraic. . .

I can't sleep. . . . I will check this again in the morning

Physics Meta

0

Q: Do we want chat notifications of potentially low-quality posts?

There is a chat bot called Smoke Detector, active on several other SE sites, that automatically checks for potentially low-quality posts and writes chat messages to notify people about them. These messages can be posted to a dedicated chat room, as for Mathematics SE, or to the main site chat, as...

ACuriousMind

11:31

Wait

-1

Q: Why do different color materal differ temperature in the same sunlight?

I have a blue, red, and green cup and put a thermometer in each. Of the 3 the blue cup had the coldest temperature inside, then green, then red. I understand there may be differences in the composition of the cups but does color reflect the sun differently? I thought blue being closer to black wo...

thermodynamics visible-light temperature reflection absorption

Slereah

waits

ACuriousMind

This question was posted and then marked as duplicate by the same user and now four people have already voted to reopen it?

No one but the user asking the question closed this question.

And yet people are voting to reopen it. One of the stranger patterns I've seen

But I'd agree it's not really a duplicate

I'm confused

0celo7

11:46

Goooood morning

8 hours ago, by Secret

@Slereah ^

@Secret 's attempt.

> The category of smooth manifolds is not nice

What does that even mean

ACuriousMind

@0celo7 It means it doesn't have nice properties. E.g. it doesn't have internal hom and it doesn't have equalizers/fiber products

Non-existence of fiber products, in turn, is indicative that it is pretty hopeless to try to take limits in general

So most of the "powerful" categorical constructions won't work, making a categorical approach to smooth manifolds alone hopeless

bolbteppa

If you try to copy

$\mathrm{H}=\frac{p^{2}}{2}+\frac{\omega^{2}}{2}q^{2}=\frac{\omega}{2}(\frac{1}{\omega}p^{2}+\omega q^{2})=\frac{\omega}{2}\frac{1}{2}(\frac{1}{\omega}p^{2}+\omega q^{2}+\frac{1}{\omega}p^{2}+\omega q^{2}) \\ \ \ \ = \frac{\omega}{2}[\frac{1}{\sqrt{2}}(\sqrt{\omega}q+i\frac{1}{\sqrt{\omega}}p)\frac{1}{\sqrt{2}}(\sqrt{\omega}q-i\frac{1}{\sqrt{\omega}}p)+\frac{1}{\sqrt{2}}(\sqrt{\omega}q-i\frac{1}{\sqrt{\omega}}p)\frac{1}{\sqrt{2}}(\sqrt{\omega}q+i\frac{1}{\sqrt{\omega}}p)] \\ \ \ \ = \frac{\omega}{2}(aa^{+}+a^{+}a)$

$H = \int d^3 x (\pi^* \pi + \nabla \psi^* \nabla \psi + m^2 \psi^* \psi) = \int \dfrac{d^3 p}{(2\pi)^3} (\dfrac{\partial \psi^*}{\partial t} \dfrac{\partial \psi}{\partial t} + \vec{p}^2 \psi^* \psi + m^2 \psi^* \psi) \\ \ \ \ = \int \dfrac{d^3 p}{(2\pi)^3} (\dfrac{\partial \psi^*}{\partial t} \dfrac{\partial \psi}{\partial t} + \omega^2 \psi^* \psi) = \int \dfrac{d^3 p}{(2\pi)^3} \dfrac{\omega}{2}(\dfrac{1}{\omega}\dfrac{\partial \psi^*}{\partial t} \dfrac{\partial \psi}{\partial t} + \omega \psi^* \psi + \dfrac{1}{\omega}\dfrac{\partial \psi^*}{\partial t} \dfrac{\partial \psi}{\partial …

0celo7

Jesus

bolbteppa

Now of course $a$ is just the fourier coefficient of $\psi$, which I can derive two other ways, but this way is interesting, how do I go from the un-integrated thing to the integrated thing more intuitively?

0celo7

The star wall is pretty terrible right now.

Unusually terrible.

Slereah

11:58

Say something funny then

Mister funny man

0celo7

I'm not funny.

bolbteppa

In other words, how is $a$ equal to an integrated thing and to an un-integrated thing

ACuriousMind

@bolbteppa There is something odd in what you do there. You switch from an x to a p integration in the first step

That doesn't really make sense.

0celo7

#rektbyACM

ACuriousMind

Or rather, it means that in the following you have $\psi$ standing for its own Fourier transform, which means that your "unintegrated form" has precisely the "missing" x integration hidden in it

manshu

12:02

we have inverse square law in gravitation...But why is the distance raised to the power 2...and not with any random number...like 1.69? Is it coincidence?We had infinite possibilities

bolbteppa

That is just what you get after you plug in a Fourier transform right? theory.caltech.edu/~kapustin/Ph205/2013/fall2.pdf It's easier if you don't break it up into two sets of coefficients, skips a lot of algebra

manshu

Why is the number had to be so simple

ACuriousMind

@manshu What do you mean "we had infinite possibilities"? What is your space of events?

bolbteppa

Okay I should put Tilde's over the Fourier transforms yes, I think it falls out of the un-integrated thing

0celo7

@manshu you can derive the inverse square law

ACuriousMind

12:04

(Probability only makes sense after you define what the space of all possible events is)

0celo7

@ACuriousMind nonsense

manshu

We had infinite possiblities means that there are infinite numbers between any two numbers

0celo7

the space of possible events is the space of all events

manshu

@0celo7 How?

bolbteppa

Have you guys ever seen the Dirac Hamiltonian done this way?

ACuriousMind

12:05

@0celo7 That's not a well-defined space

@bolbteppa Done what way?

bolbteppa

The way I just wrote the KG hamiltonian, where you derive the fourier coefficients of the wave function as a by-product through factoring

ACuriousMind

@manshu Well, but why do you think any other number was possible to begin with?

bolbteppa

I just want to skip as much work as possible :p

manshu

@ACuriousMind Coz there are infinite numbers...

bolbteppa

Think I got canonical/Lorentz EM Hamiltonian looking basically the same

ACuriousMind

12:06

@manshu I was born with ten fingers - did I have "infinite possiblities" (to have 13248 fingers, for instance)?

Slereah

@ACuriousMind Never give up on your dreams

manshu

There are people with 11 fingers...So you mean that sometimes it doesn't follow inverse square law? it's gibberish

ACuriousMind

@manshu No I mean that "there were infinite possiblities" is just not substantiated by anything! Not everything that is a number could have been any number.

But, as for why the square in the inverse square law is special, see e.g. this question.

skill patrol

^

ACuriousMind

Sure, I could have had 9 or 11 fingers, but 13248 fingers are clearly absurd

manshu

12:10

"Not everything that is a number could have been any number."...Sounds like "I am the hero they deserve, not the one they need"

lol

skill patrol

look at the linked question @manshu

manshu

yeah.. i was reading it

ACuriousMind

So, what tells you in the case of physical laws which numbers are "reasonable" and which "absurd"? I think nothing, you can't tell either way, and it is thus meaningless to speak about the "possibility" of laws being different. You can ask whether or not we know any deeper reason that forces the law to be like that, but to speak of "possibilities" for physical laws always has a multiverse-y touch to it that I don't like

manshu

In short... you mean to say that "This is how it works"...right?

skill patrol

why is there a 2 in E = mc^2?

manshu

12:17

Coz this is how it works

skill patrol

without a 2 it would not be a true equation

manshu

More discussion on this topic can lead to severe damages on the way you think about numbers...

0celo7

@ACuriousMind why not

@skillpatrol dimensional analysis

what is a faithful functor

the opposite of a slutty one?

manshu

@0celo7 talking about dimension analysis...Dimensions of E are given by using gravitational force

remember "mgh"?

Kinetic energy will also be affected maybe

damn...I just broke the physics...sorry for that

0celo7

...what

manshu

12:31

never mind

0celo7

> Trump rescinds pledge to back Republican nominee; Cruz, Kasich refuse to commit support

Damn son

> Trump, who followed Cruz on the town hall stage, said he didn't need a promise of support from Cruz.

manshu

lol

trump is trolled

0celo7

@ACuriousMind People with small heads are so damn smug.

Like physically small skulls.

manshu

is he in this room?

ACM?

0celo7

no

manshu

12:36

I thought ACM blocked me too... :p

0celo7

He did

manshu

how do you know?

0celo7

He talks in his sleep.

manshu

oh...he must be murmuring about me...

cursing me

0celo7

No

manshu

12:39

cursing you?

0celo7

No

bolbteppa

13:17

How would you explain the Poincare half-plane model $ds^2 = \dfrac{dx^2 + dy^2}{y^2}$ en.wikipedia.org/wiki/Poincar%C3%A9_half-plane_model I mean wtf is up with this?

HDE 226868

@DavidZ Thanks. Yeah, I considered doing it myself, but I figured it might be better to have a Physics mod do it.

0celo7

13:59

@bolbteppa it's a hyperbolic plane or something like that

Check Zee's book, he talks about it.

bolbteppa

Cool, which book?

3075

hi

0celo7

@bolbteppa which book would talk about geometry...

bolbteppa

Thanks, so "the space at one value of $x$ looks exactly the same as the space at some other value of $x$, but it is not translation invariant in $y$."

0celo7

Is that from Zee?

I sadly do not have his book memorized any more.

bolbteppa

14:09

Yeah, pages 67 to 68, basically just gives an example of how to use this model, no idea what it's about still

0celo7

@bolbteppa you should refine your question

I don't know what your confusion is

Did you read the wiki article?

bolbteppa

What the hell is this model, what is it about, why would anybody think of such madness and why is it obvious you should use it in scenario X

0celo7

It's not a model, it's a crazy space!

I think it has to do with hyperbolic spaces, but I don't know specifics.

Maybe check do Carmo.

Slereah

It's a hyperboloid of two sheets~

Secret

[Random] Claim: Problem of evil is due to the lack of unlimited resources for all possible worldviews to realise their ideals

For starters, there are no infinite copies of every of us to serve someone, to be tortured by a sociopath, to be protected, to be saved from sociopaths etc. etc etc.

Slereah

14:16

go back to Philosophy SE

bolbteppa

How is it linked to a hyperboloid of two sheets?

Secret

PhSE is dead unfortunately, hence why the random stuff end up here (the last stable chat that allow discussion of off topics)

Slereah

Can't find a direct morphismmorphism

But there is one from hyperboloid to Poincaré disk

Poincaré disk model

In geometry, the Poincaré disk model also called the conformal disk model, is a model of 2-dimensional hyperbolic geometry in which the points of the geometry are inside the unit disk, and the straight lines consist of all segments of circles contained within that disk that are orthogonal to the boundary of the disk, plus all diameters of the disk. Along with the Klein model and the Poincaré half-space model, it was proposed by Eugenio Beltrami who used these models to show that hyperbolic geometry was equiconsistent with Euclidean geometry. It is named after Henri Poincaré. The Poincaré ball model...

$$(t, x_i) = \frac {\left( 1+\sum{y_i^2},\, 2 y_i \right)} {1-\sum{y_i^2}}$$

$$y_i = \frac{x_i}{1 + t}$$

0celo7

@Slereah dammit man what is your opinion on the goblin Secret drew

Slereah

Not ideal

Bass

14:20

@bolbteppa Do you understand what a manifold with positive or negative curvature is?

The Poincaré model is a simple example of a 2-manifold with a negative curvature.

bolbteppa

Yeah but I still have no feel for this nor idea about why anybody cares, this nonsense about cold rulers seems to sync with Zee though!
https://books.google.ie/books?id=TABicHVMQhMC&lpg=PA258&ots=qXVFhA-916&dq=Hyperbolic%20upper%20half%20plane%20metric&pg=PA63#v=onepage&q=Hyperbolic%20upper%20half%20plane%20metric&f=false

Bass

@bolbteppa "...why anybody cares...", do you want to know about its applications?

bolbteppa

I mean, how would you motivate the necessity of the upper-half plane model to a mathematical child on a desert island basically

Bass

AFAIK there are many applications of the Poincaré disk in string theory and CFT, but you have to ask others about that. Besides its applications, it's often used in basic differential geometry to illustrate the concept of a metric.

You know about metrics, like $g_{\mu\nu}$ in Riemannian geometry?

Slereah

@bolbteppa You can't eat the upper half plane model

bolbteppa

14:35

Yeah, but it looks like you can use it to model frozen food shrinking according to the page I linked to

0celo7

@bolbteppa Necessity is a poor thing to require in abstract math.

Bass

@bolbteppa Yes, because the metric is like a ruler that you use to measure things. Normally, rulers have always the same length, so they are pretty boring metrics. But if temperature changes, the rulers will change their length. That's where Riemannian metrics start to get interesting.

bolbteppa

Understanding is a vital thing in abstract math though - Why not spend your time computing integrals in random coordinate systems? Obviously you don't because you want to play with interesting ideas, understanding where the upper-half plane comes from means you don't fall into the trap of treating it like doing a double integral in some random difficult coordinates :p

@Bass Yeah but why change it in this way, why model it on Euclidean lengths, very arbitrary the way you're stating it

Bass

@bolbteppa There are two ways of dealing with curved spaces: 1) You embed them into a higher-dimensional Euclidean space and "induce" the Euclidean metric of the surrounding space on them. For example the surface of a ball is a two-dimensional manifold that's embedded in 3-dimensional Euclidean space.

But sometimes this is not possible, or there are other reasons to avoid it. For example, we know that our 4-dimensional spacetime is curved, but we don't know whether or how it is embedded into a higher-dimensional space.

2) But you can calculate many things intrinsically, which means you don't have to embed the space into a higher-dimensional space, you just analyze it using the metric.

FenderLesPaul

@0celo7 yo did you see the talk?

Bass

14:49

The Poincaré disk model is an example of a space which looks flat to us if we ignore the metric. After all, it's a flat plane. But when you change the metric, the manifold you get is intrinsically curved.

FenderLesPaul

@Bass the poincare disk does indeed have applications in CFT

but mainly as a computational tool

it's used a lot to conformally map hard problems to easier problems

e.g. path integral calculations on half planes

bolbteppa

There is a secret behind this that makes it all obvious

Bass

@FenderLesPaul IIRC it also plays a role in AdS spaces, which also have constant negative curvature. But I don't know the details.

FenderLesPaul

@Bass yep

there's a local coordinate system for AdS called the Poincare patch

and the AdS metric can be put in a manifestly Poincare disk form in that patch

0celo7

15:05

@FenderLesPaul what

FenderLesPaul

Did you

see the talk I posted

0celo7

I didn't know you posted one

FenderLesPaul

Wow

just wow

0celo7

I would say I'm sorry, but I'm not

And I don't lie

user54412

Oh look, semi-famous person spotted: physics.stackexchange.com/users/112768/john-baez

3

FenderLesPaul

15:13

Who that is

Oh

Baez

he's Joan Baez's cousin!

0celo7

@ChrisWhite Would you happen to know how to tell when a book on Springer is being released?

or maybe can you access rd.springer.com/book/10.1007%2F978-3-319-26654-1 already with your Princeton powers

I can't even buy it!

FenderLesPaul

15:34

Peter Petersen

lol

0celo7

@FenderLesPaul can you access it?

I want to learn some more global Riemannian geometry and my prof recommended Petersen among others

FenderLesPaul

I can't off campus

if you give me 2 weeks then I can

actually week and a half

bolbteppa

How much of a heart attack would you have if I wrote

$\mathrm{H} = \int d^3x(\pi \partial_0 \psi - L) = \int d^3x(i\psi^+ \partial_0 \psi) = \int d^3x(\overline{\psi} i \gamma^0 \partial_0 \psi) \\ \ \ \ = \int \dfrac{d^3p}{(2\pi)^3}(\hat{\overline{\psi}} \varepsilon \hat{\psi}) = \int \dfrac{d^3p}{(2\pi)^3}\dfrac{\varepsilon}{2}(\hat{\overline{\psi}} \gamma^0 \gamma^0 \hat{\psi} + \hat{\overline{\psi}} \gamma^0 \gamma^0 \hat{\psi}) \\ \ \ \ = \int \dfrac{d^3p}{(2\pi)^3}\dfrac{\varepsilon}{2}(\hat{\overline{\psi}} \gamma^0 u \overline{u} \gamma^0 \hat{\psi} - \hat{\overline{\psi}} \gamm…

0celo7

that's nothing

you ain't a real man until you've calculated a second variation

0celo7

16:02

@FenderLesPaul are you around

FenderLesPaul

16:16

@0celo7 sup

what

0celo7

@FenderLesPaul I hate topology

that is all I have to say

FenderLesPaul

Topology hates you

0celo7

good

I slapped the shit out of it

It would be weird if it didn't hate me too

FenderLesPaul

domestic violence of the homeomorphic character

0celo7

oh I homeomorphiced him good

FenderLesPaul

16:25

they*

0celo7

what?

FenderLesPaul

topology is gender fluid

or should I say

gender homeomorphic

0celo7

no

hubot

17:02

Hello!

3075

hi

0celo7

why are you so happy

0celo7

17:32

@Slereah out of fucking nowhere a wormhole appeared and delivered Visser to me...

Slereah

hurray

0celo7

Not in great shape

Corners are messed up

Slereah

Eh

As long as the pages don't detach

0celo7

The used book place sent it cross-country in a plastic sleeve

Couldn't be bothered to put it in a box!

Slereah

Hey check one thing for me

Go to page 195

And tell me the page number that follows

Dvij

17:36

In connection to yesterday's discussion. publish.csiro.au/?paper=PH920591 Would someone like to discuss this paper?

0celo7

196

Slereah

Hm

I guess only my copy is fucked up

My copy is like

0celo7

You want a pic?

Slereah

193, 194, 197, 195, 196

And then normal

0celo7

Holy crap that last problem

Slereah

17:40

Yeah it's a tough one

0celo7

I wonder if the goblin could solve it!

Slereah

I'm sure he already has

0celo7

I think the GR goblin is really smart

He just smoked too much weed or something and something happened to him

3075

recommend me an algebra book please.

Bernard Meurer

Hey folks

papa bless

0celo7

17:52

@3075 I don't know any algebra

3075

:'(

Slereah

If you get frustrated by a lack of stated proofs you're not gonna have a lot of fun with Visser btw :p

3075

amazon.com/Algebra-2nd-Edition-Michael-Artin/dp/0132413779

should I read? ^

Bernard Meurer

Reading is for loosers

just sleep on top of the book

3

it works the same, I swear

3075

learning by osmosis?

Bernard Meurer

17:54

Uhum

but you have to really press against the book

0celo7

@Slereah does he at least give references

Slereah

Plenty of references

0celo7

ok, but no GR today

Slereah

Do like me

0celo7

I need to make a blog post

Slereah

17:55

Bake some potatoes instead

2

3075

artin or hungerford?

0celo7

I'm going to prove some things on the blog today about vector spaces

Bernard Meurer

@Slereah The best solution to a problem I've seen in this chat so far

Slereah

I am making a burger and baked potatoes

Tasty eatin'

0celo7

I want to do a post on vector spaces from the manifold PoV

but I need some stuff about their topology first

@Slereah I wonder who has more GR books now

Slereah

18:00

Iunno

0celo7

@Slereah well, count'em!

Slereah

Purely serious GR books, 9

0celo7

no QFTCS

did you count Visser?

Slereah

Not counting quantum gravity, diff geom and QFT on CST

I did

0celo7

yeah, I have 9 as well

oh that's right you have Stephani

Slereah

18:03

Visser, Hawking Penrose, Hawking Ellis, Walf, Callahan, Stephani, Carroll, Straumann and that one on scalar fields in GR

0celo7

Hawking Penrose?

Slereah

"the nature of space and time"

hubot

@DeNiSkA: Teachers said that Krotov is too hard me. What should I think about this?

0celo7

Zee, Visser, Straumann, Hawking-Ellis, Sachs-Wu, Penrose, Wald, Weinberg, I can't count

only 8

9 if you count BEE I guess

Slereah

Would you recommend SW, outside of the notation

0celo7

18:05

but they say at the beginning that they have no interest in physics

@Slereah I haven't spent enough time with it, tbh

I got it because it has some interesting stuff that's not standard

DeNiSkA

@hubot after doing Resnick-halliday (mainly newton's laws and rotational dynamics) hardness vanishes!!

0celo7

like photon gasses

Slereah

"Stuff that is not standard" is good

That's the problem with those books

0celo7

and they also have rigorous proofs of some common lore

Slereah

You need a fuckload to have most aspects of the theory

hubot

18:07

I'm in 5 chapter forces and dynamics

0celo7

also SW has a shitload of exercises, which might be fun one day

hard exercises

hubot

I'm also doing exercises from 3, 4 and 5 chapter

3075

@hubot brings back memories.

0celo7

@Slereah basically, SW is rigorous as fuck

they do the whole variation of a curve thing with an induced connection, some fancy stuff there

but I got it last week, only read a few pages here and there

DeNiSkA

@hubot i have not yet completed krotov completely , asterisked questions REALLy kill me!!!

@BernardMeurer you know C++ , right?(i think i have asked)

Obliv

18:10

@0celo7 how many of those GR books did you read through? WTF do I have to read through that many books to pass a GR course? :(

Bernard Meurer

@DeNiSkA Yes, I know more C than C++ though

and more Python than C

and more magic than Python

hubot

@DeNiSkA Have you finished Feynman exercises? Do you also this?

DeNiSkA

@hubot not completely but i am doing in order!!

0celo7

@Obliv around 15

hubot

@DeNiSkA Do you know something about programming, Wolfram Alpha, Matlab, QCL, electronics etc.?

DeNiSkA

18:13

@hubot yup i have started C++ and SQL.

Obliv

@0celo7 I think I'd turn into a shut-in hermit if I read through 15 GR books in 1 semester.

@0celo7 I'll just start learning it asap before I have to take that course x.x

DeNiSkA

@BernardMeurer then i think you can answer my question (although C is mother of all C's)

0celo7

@Obliv I like to think @Slereah and I are beyond first semester GR

hubot

@DeNiSkA I'm studying C# and Unity3D (game physics mainly) for two years.

0celo7

dunno if that's true or not

Bernard Meurer

18:14

@DeNiSkA Go for it, I'll help you if I can

Never ask if you can ask a question :)

hubot

I'm beginner in Unity3D.

DeNiSkA

@hubot cool, i will also try unity (for games)

Slereah

Oh man

Burger and potatoes

I am stoked

hubot

@DeNiSkA Do you parents afraid FPS and horror games? My mum is trying control what I'm creating games in Unity3D.

0celo7

dude topology proofs are long chains of theorems

I hate topology

Obliv

18:17

@0celo7 Oh thought you guys were taking the course as of right now.

0celo7

@Obliv no

I have no interest in taking a course on GR, at least from the physics department

DeNiSkA

@hubot nope and i am not that expert who can start coding a game :-)

Obliv

@0celo7 You're weird man.

0celo7

@Obliv what

no one has ever said that to me before

Obliv

@0celo7 Owns 9 GR books but doesn't take the course at school.

0celo7

18:20

@Obliv from the physics department

Obliv

@0celo7 where else can you take a GR course at a school o_o

0celo7

I do not need someone to tell me what the equivalence principle is or how to calculate the orbit of mercury

@Obliv my advisor in the math department has been known to teach a course on geometric analysis with applications to GR

he's also taught a straight GR course before, too

using Hawking-Ellis and O'Neil

DeNiSkA

@BernardMeurer ^

TylerH

Does Qmechanic ever drop by here?

Bernard Meurer

Why did you make a const int instead of a preprocessor directive #define for that value?

msdn.microsoft.com/en-us/library/teas0593.aspx

Obliv

18:23

@0celo7 to each his own I guess. As long as you enjoy learning it, the angle you take doesn't make much of a difference.

Bernard Meurer

What's the third line supposed to do?

and the fourth

0celo7

@Obliv I'm interested in the math of GR, not the physics

an intro physics course will stress, well, physics

Bernard Meurer

why ++ptr and not ptr++?

0celo7

and the "advanced" course here is just cosmology

DeNiSkA

ignore third line because it's use is inside for loop and my confusion is on fourth line!

Slereah

18:24

Those are some good potatoes

Bernard Meurer

@DeNiSkA What error are you getting?

Again, what do you hope to accomplish with the fourth line?

DeNiSkA

Obliv

@0celo7 What's so interesting about the math of GR? I have a vague picture of it as something to do with diff geometry and topology.

DeNiSkA

@BernardMeurer code for counting vowels in word mollie

Bernard Meurer

@DeNiSkA Your switches have no break statement, they are falling through

0celo7

18:28

@Obliv I'm also interested in Riemannian geometry

Bernard Meurer

cprogramming.com/tutorial/lesson5.html

0celo7

and GR is modified Riemannian geometry

Bernard Meurer

@DeNiSkA en.cppreference.com/w/cpp/algorithm/count

DeNiSkA

yup, because if the letter is one among "a, e ,i ,o ,u"
vowel has to get incremented

Bernard Meurer

Still, fallthroughs are ugly

DeNiSkA

18:30

@BernardMeurer ;)

Bernard Meurer

because there's no way for the second person to know they were intentionally done by the first

Obliv

@0celo7 what the heck Riemann'

DeNiSkA

true

Obliv

@0celo7 his math is used in GR? this guy is the mvp of the 19th century i swear.

TylerH

@DeNiSkA is that supposed to run against user-inputted data?

DeNiSkA

18:31

@TylerH no! only for word "Mollie"

Bernard Meurer

Also, why aren't you using std::string

It's so much better than c-style strings

363

Q: How to convert std::string to lower case?

I want to convert a std::string to lowercase. I am aware of the function tolower(), however in the past I have had issues with this function and it is hardly ideal anyway as use with a string would require iterating over each character. Is there an alternative which works 100% of the time?

c++ string c++-standard-library

because you can call it's objects

vzn

guys talking about code? need a favor =D

Bernard Meurer

tutorialspoint.com/cplusplus/cpp_strings.htm

DeNiSkA

@BernardMeurer yup, but i am having practice on pointer and arrays so i preffered C-style string !!

Bernard Meurer

@DeNiSkA I just hate c-style strings :p

Null terminated monsters they are

DeNiSkA

18:34

@BernardMeurer haha!

vzn

@BernardMeurer what kind of stuff do you code

DeNiSkA

Now my major question:
in fourth line " *ptr=name " this statement makes "ptr=M", right?
my question not yet over...

Bernard Meurer

@DeNiSkA gist.github.com/anonymous/6b28a12dc0170a789354bab9d36ab6f8

this is how I'd do this

Note how I organized the if statement by usage of the vowels in the english language

Letter frequency

The frequency of letters in text has been studied for use in cryptanalysis, and frequency analysis in particular, dating back to the Iraqi mathematician Al-Kindi (c. 801–873 CE), who formally developed the method (the ciphers breakable by this technique go back at least to the Caesar cipher invented by Julius Caesar, so this method could have been explored in classical times). Letter frequency analysis gained additional importance with the development of movable type in Asia in 1040 CE and in Europe in 1450 CE, where one must estimate the amount of type required for each letterform, as evidenced...

This was the code is more likely to run a little faster

because the if will end first

having done less comparisons

DeNiSkA

@BernardMeurer hmmm, code looks quite better!

Slereah

18:54

Help

I ate too many potatoes

hubot

@Slereah WHAT?

0celo7

@Slereah lol

Slereah

I paid for my potato hubris

hubot

@BernardMeurer What's the use off this app you have sent me?

Bernard Meurer

@hubot App? I haven't sent you a thing

hubot

18:59

@BernardMeurer gist.github.com/anonymous/6b28a12dc0170a789354bab9d36ab6f8

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