The Nineteenth Byte

Lyxal

00:00

we don't let y'all have all the fun

rak1507

damn it, aussies are so lazy stealing our names

Lyxal

JoKing is (iirc) down south from me

ChartZ Belatedly

The US isn't the only place that steals place names :P

That's impressive

Haha, I'm a child :P

Lyxal

@ChartZBelatedly no you aren't

Queens Wharf Tower

look that up

then you'll be a child

rak1507

lol

ChartZ Belatedly

00:03

It's in NS(F)W as well :P

Lyxal

lol

> Queens Wharf Tower, the phallic Colossus which menaced the city skyline for 30 years, is now a pile of twisted green and cream-coloured metal next to Wharf Road.

from a local newspaper

Redwolf Programs

I've published my spec for GCaaPL

Time to go answer some questions with it

I have to go in a few minutes for dinner though

I don't think it's turing complete, but I know of a few questions I can answer with it

Lyxal

@RedwolfPrograms link?

ChartZ Belatedly

@RedwolfPrograms I hate this. Why isn't it "ctrl+1 to ctrl-9 for n'th tab, ctrl-0 for final tab"?

Redwolf Programs

@ChartZBelatedly That would be too logical

Apparently Ctrl + 0 resets to normal zoom

ChartZ Belatedly

00:08

CMP: What zoom do you use on CGCC?

Redwolf Programs

Normal zoom on a 1366x768

Lyxal

normal

rak1507

@ChartZBelatedly 80 apparently

ChartZ Belatedly

@ChartZBelatedly 90

Redwolf Programs

Got to go for now, I'll answer some questions in Chrome soon :p

Wezl

00:10

@ChartZBelatedly 0% :)

@Lyxal churchofjesuschrist.org/broadcasts

rak1507

00:36

cmp: what is your favourite answer you've ever seen on the site?

ChartZ Belatedly

I've found a Wikipedia page that's inspired me to write a challenge. The problem is that I understand the contents of the wiki page, but given that it's a mathematical topic, I know that others users have a much better knowledge base of the subject. So, I kinda feel a bit like a fraud writing out a challenge spec based on my limited understanding of the topic :/

It's like a new calculus student writing a "Given ax^n, output the derivative"

rak1507

00:54

@ChartZBelatedly which would be a perfectly reasonable challenge

doesn't matter if people know more about it than you

ChartZ Belatedly

Yeah, but I'm very nervous about getting something wrong :P

rak1507

that's what the sandbox is for :P

Wezl

01:08

@rak1507 I don't know the exact one, but the one that got me interested in APL

probably

rak1507

neat

ChartZ Belatedly

@rak1507 This one :P

rak1507

how did I know what that was going to be before I even clicked

ChartZ Belatedly

It's caird-rolling :P Like rick-rolling but with that post :P

rak1507

don't give lyxal any ideas

Lyxal

01:16

Give me all the ideas

New Sandboxed Posts

01:28

0

A: Sandbox for Proposed Challenges

Quoted rational numbers Quote notation is a way of expressing rational numbers based on the concept of \$p\$-adic numbers, written in the form \$x'y\$. The quote indicates that the number to it's left (\$x\$) is "repeated" infinitely to the left. For example \$3' = \: ...3333\$ and \$764'31 = \: ...

Redwolf Programs

01:44

@ChartZBelatedly That would be (a * n)x, right? (am a new calculus student :p)

Lyxal

@ChartZBelatedly anx^(n-1) iirc

Redwolf Programs

Oh yeah that's what I meant

Or what I should have meant

rak1507

lim h->0 (a(x+h)^n - ax^n)/h

Lyxal

yeah okay settle down. no need to use first principles on us

rak1507

@Lyxal I'll use second principles instead

Lyxal

01:47

@rak1507 stoopid, there is no second principles

but real golfers use 69th principles

rak1507

that's what they want you to think

HyperNeutrino

since the indefinite integral of anx^(n-1) based on product can be decomposed into an times x^(n-1) and using power rules we get x^n / n, the product gives ax^n, so the integral is ax^n+C, and so since the antiderivative of anx^(n-1) is ax^n, we can logically conclude that the derivative of ax^n is also anx^(n-1).

Lyxal

@rak1507 there's first principles and then there's 69th principles

get it right

rak1507

@HyperNeutrino that's cheating

HyperNeutrino

my bad

Redwolf Programs

01:49

@HyperNeutrino I know there's something cool happening but I don't know enough math to understand it :(

rak1507

lol

Lyxal

@HyperNeutrino thanks for reminding me how much i have a mild dislike towards integration

integration is cool but not cool at the same time

HyperNeutrino

i hate integration too

Lyxal

like I don't hate it, but I wouldn't want to spend all my day integrating

CMQ: how to bitwise or a string and a number

context: golfing language built-in suggestions needed

HyperNeutrino

well, we see that the derivative of f(x)=x is f'(x)=1, then if we assume that d/dx x^(n-1) is (n-1)x^(n-2), which holds for n=2, then we see that x^n=x^(n-1) * x so by product law, d/dx x^(n-1) * x = (n-1)x^(n-2)*x + x^(n-1)*1 = (n-1)x^(n-1)+x^(n-1) = (n-1+1)x^(n-1) = nx^(n-1)

therefore, by induction, d/dx x^n = nx^(n-1)

Wezl

01:53

@HyperNeutrino flagged as offensive :) (no math on weekends)

rak1507

@HyperNeutrino I love integration, differentiation is tedious and boring, but integration is interesting

Redwolf Programs

Differentiation is all I know how to do but I like it

HyperNeutrino

@rak1507 oh? huh, for me i find it the opposite :P well actually i don't really find differentiation that interesting but integration is much more tedious for me at least

Lyxal

@HyperNeutrino same.

ChartZ Belatedly

@HyperNeutrino You know the proof of the power rules for integration typically rely on the derivative power rules and the fundamental theorem of calculus right?

Wezl

01:55

@Lyxal obv just do what C does

ChartZ Belatedly

Integration is better, because you actually have to think :P

Lyxal

@Wezl what does C do?

ChartZ Belatedly

Differentiation is science, integration is art

Redwolf Programs

C doesn't have strings, does it?

rak1507

@ChartZBelatedly exactly

Redwolf Programs

01:55

Just arrays of code points

Wezl

@Lyxal treats the string as a char * and computes str | num. Simple

rak1507

@HyperNeutrino a good integration problem is actually interesting and requires thought

Wezl

(and useless)

ChartZ Belatedly

@Lyxal Error

Lyxal

@ChartZBelatedly where is the fun in that.

Redwolf Programs

01:56

I use bitwise or as combinations of n items, but you probably already have an operator for that

Lyxal

@RedwolfPrograms correct

ChartZ Belatedly

@HyperNeutrino Browse the top voted questions or answers on the integration tag on Math.SE. The elegance of some of them are just insane

Also, I write so many code golf explanations on my phone, that the suggested text after I type ## is How it works :/

Lyxal

:o you know the pains of mobile code golfing too!

finally someone understands my suffering

ChartZ Belatedly

I post about 40% of my golfs from my phone :P

Lyxal

same

41 secs ago, by Lyxal

finally someone understands my suffering

Redwolf Programs

01:59

How do you do anything code related on a phone...

ChartZ Belatedly

I golfed the Enigma machine on my phone initially, then had to switch to computer :P

Lyxal

@RedwolfPrograms with great pain

ChartZ Belatedly

@RedwolfPrograms With difficulty

Lyxal

I've golfed in scratch on mobile

it was pain

but worth it

ChartZ Belatedly

Jelly's fun on mobile :P

Lyxal

02:00

yes

Redwolf Programs

I was about to ask how that's possible

ChartZ Belatedly

I've been trying to create a custom mobile keyboard for it

Lyxal

atoms/quicks/syntax page

and copy-paste

ChartZ Belatedly

It's not going well

Lyxal

easy

ChartZ Belatedly

02:00

@RedwolfPrograms Copy-paste, same way I do it on a laptop

Redwolf Programs

I wish you could make custom keyboards for Chrome OS

ChartZ Belatedly

It tries to autocorrect the programs sometimes

Lyxal

sometimes it deletes characters when I copy-paste

and when i try to put more than one space it inserts a .

Redwolf Programs

Why would you ever need more than one space in a golfing language

Lyxal

for explanations and for creating space to insert a built-in

ChartZ Belatedly

02:02

@Lyxal I turned that off a while back :P

@RedwolfPrograms Explanations

Redwolf Programs

I just never leave my house except without my laptop, easy :p

Lyxal

@RedwolfPrograms boring and trivial

no fun

Redwolf Programs

I also never leave in the first place

Except for school

Lyxal

imagine having school

ChartZ Belatedly

My phone is irritatingly good at identifying - then acting on - capital letters, even with hooks and dots, so I've had autocorrected programs and auto-title-case programs, which completely fucks them up

The number of times it's corrected ɗ to Ɗ Would honestly be impressive, if it didn't completely destroy the chain parsing of my program

Lyxal

02:06

then use 05AB1E

Redwolf Programs

Imagine having parsing

Lyxal

swiftkey surprisingly has a lot of 05ab1e characters built-in

HyperNeutrino

@ChartZBelatedly yeah i'm fully aware of that, i'm 100% trolling lol

@rak1507 that's true. yeah fair enough, differentiation is usually a lot simpler cuz it's just a combination of the same three rules

idk man i'm just too lazy to think at this point i've been doing way too much math and cs non-stop like i don't think i've gone more than 2 days in a row without working on some sort of uni assignment for a few months

rak1507

fair enough

Original Original Original VI

Hola

Lyxal

02:08

Howdy

HyperNeutrino

Bonjour

Original Original Original VI

Why are y’all discussing math?

Lyxal

@OriginalOriginalOriginalVI how's my favourite rickrolling apprentice?

Original Original Original VI

@Lyxal Your only rock rolling apprentice is doing fine

Lyxal

@OriginalOriginalOriginalVI have you been practising lately?

Original Original Original VI

02:10

@Lyxal Yup, April Fools’ was fun :p

Lyxal

@OriginalOriginalOriginalVI very good

Original Original Original VI

@ChartZBelatedly Art doesn’t have a correct solution at the end, nor is it sometimes impossible. I’d say it’s like programming- you sometimes find a beautiful way to do it, and sometimes you end up throwing your chair out the window.

ChartZ Belatedly

@HyperNeutrino tbh I can't tell rn. It's far too early/late for me to try to understand tone from text :P

HyperNeutrino

02:32

@ChartZBelatedly fair enough lol; text is terrible for conveying tone regardless

Razetime

02:47

yo

Original Original Original VI

03:00

@Razetime yoyo

Razetime

morning

Original Original Original VI

Night

I should go sleep now, actually

Wezl

yah

HyperNeutrino

good morning/afternoon/evening/night, how are y'all doing on this fine day/evening/night

Original Original Original VI

I’m tired :(

Wezl

03:08

hey, I was going to say that, now I'll have to say something unique

graham crackers don't taste at all like any Grahams I know

I made some and they taste like crunchy flour

Original Original Original VI

Good to know

What do Grahams taste like?

Wezl

don't know :P

Original Original Original VI

Oh ok

HyperNeutrino

@Wezl well, I guess this is vacuously true in that case :P

Original Original Original VI

I would taste a Graham to test that but...

Wezl

03:12

if vacuously means what I'm guessing it does, then yes

yep

HyperNeutrino

vacuously true is when "all <A> are <B>" is true because <A> is empty

Wezl

yep

HyperNeutrino

04:15

wew, it seems like best of 2020 is finally off the sidebar

relocked it; if it comes back sometime later, i might just give up and let it stay lmao

Redwolf Programs

Finally, we can now pretend there was some weird leap century thing and it just went straight from 2019 to 2021

HyperNeutrino

what do you mean pretend, there wasn't anything between 2019 and 2021 was there?

Redwolf Programs

You know that feeling when there's a river and you need a reliable source of hydropower and you're just like "dammit"

HyperNeutrino

uh, water you talking about? sorry, having trouble following the flow of this conversation

Lyxal

@HyperNeutrino dam. That joke really made laughter stream out of me.

Monica Cellio

04:50

@pxeger Hi, Codidact team member here. I'm not sure what issue you're referring to, but if we've missed a security issue we certainly want to know about it. Would you be willing to drop a note to [email protected] with the details? Or a reminder of where you reported it before? Thanks!

Deadcode

06:11

@Neil Yay! Managed to do what I had been trying from the outset, to combine base 2 and 10 into a single expression in basic ECMAScript. It saved 4 bytes: codegolf.stackexchange.com/questions/211840/…

Lyxal

I have 395 answers and 395k people have supposedly seen my stuff

Well done SE chat for screwing up my chatting experience

pxeger

@MonicaCellio I did report it by email and got a reply from Manasseh Katz in July last year, but never got another follow up and it hasn't been fixed. Would you like me to report it on the security portal? (which I don't think existed when I reported this), or resend it to that address?

Razetime

06:31

@RedwolfPrograms github.com/RedwolfPrograms/GCaaPL please oh please implement this in selenium or something

Lyxal

06:58

looks like march was a bad month for 05ab1e

it's gone from 2nd to 11th on the elo leaderboard

Wasif

07:37

@Razetime the project seems nice, I am interested, where we can get a full list of google chrome keyboard shortcuts?

Deadcode

08:10

More bugs found in regex engines, from the same CGCC challenge: bugs.python.org/issue43726 and bugs.ruby-lang.org/issues/17774

Delfad0r

08:38

@RedwolfPrograms OMG YOU ACTUALLY DID IT

Razetime

08:49

@Deadcode wow lmao

@Wasif idk, a google search might help

Wasif

@Razetime searches don't seem to give a full list (Highest I have found 145)

I am planning to write a Python Implementation of the GcaaPL using Selenium

Razetime

lol, le;t's wait for redwolf to release a spec

Neil

09:48

@Deadcode Nice! I notice that you no longer need the |^x alternative; does that help at all for the other versions?

Deadcode

@Neil Thanks! Yes, it's still needed for the other versions

Neil

@Deadcode what I meant was, does porting that algorithm result in a larger or smaller byte count? (the unported byte count seems to be smaller)

Deadcode

10:10

@Neil A larger byte count, but only by a little.

I can also reduce the generic regex by 2 bytes by removing the \B, but then it falsely matches 2

New Main Posts

11:40

1

Q: Implement the Levine sequence

I became interested lately in the Levine sequence, and I decided to post a Code Golf challenge. Introduction Note that I learned it from a Numberphile Video, where Neil Sloane explains it better. I recommend you to watch his Video. But for a quick Introduction: The Levine Sequence is made from ...

ChartZ Belatedly

13:56

CMCnR: Cops, choose three prime numbers that all have unique digits and share no digits between them (e.g. 23, 59 and 7) and multiply them together. Reveal the product and one of the three primes (your choice). Robbers, find either of the other 2 primes

New Sandboxed Posts

14:17

0

A: Sandbox for Proposed Challenges

Computer battery "output machine" (?) If there are any better titles please post them in the comments code-golf If any more tags might be appropriate, please post them in the comments The task here is to create a program which can output a battery's percentage at all times. It will be given inp...

Original Original Original VI

14:32

@ChartZBelatedly Here's an easy one: the product is 30 and one of the primes is 5.

pxeger

14:46

@OriginalOriginalOriginalVI lemme guess, is it 1 and 61?

Original Original Original VI

15:02

@pxeger ? No, it's 2 and 3. Were we supposed to multiply the digits?

pxeger

@OriginalOriginalOriginalVI it's obviously 2 and 3

1 is not even prime

Original Original Original VI

15:17

@Jonah I can't give you a bounty on the answer you've requested it on, since I have to award 500 rep on that question. Do you have another answer that I could award it on? (and then I'd link to your original answer)

Newly Featured Questions

15:29

26

Q: Regex Golf: Regions of Italy vs. States of USA

We've already got a meta-regex-golf problem as inspired by the xkcd comic But, this regex golf looks fun, too! I want to distinguish between the states of the US and the regions of Italy. Why? I'm a citizen of both countries, and I always have trouble with this*. The regions of Italy are ...

code-golf regular-expression

38

Q: "Fill the Grid" Problem

A challenge with simple rules but non-trivial algorithms. :-) Task Take input in the form of space-separated integers: N A B S Where N is the side length of a 2D square matrix filled with unique numbers (integers) between A and B inclusive. For each row and column in this matrix, the sum is ...

code-golf math grid

HyperNeutrino

15:58

@ChartZBelatedly got through all of the faq-proposed questions; I pretty much ended up agreeing with all of your reasoning for each of the posts, lol

ChartZ Belatedly

@HyperNeutrino Thanks :P

Tbh most of them weren't especially divisive

HyperNeutrino

Yeah, they were all pretty much "things that are pretty frequently asked" and "things that aren't frequently asked", so... not too hard to decide :P

HyperNeutrino

16:12

I'd like to get a general interest check on new room owners for TNB; what does everyone think? If I don't get enough responses / enough of a consensus here I'll bring it to meta as well (I still need to confirm with the other mods).

9

(As in, should we have more, not who should be one; we'll have an election process if we decide we want more)

For reference, none of the current room owners of TNB can be pinged, and based on mod activity in chat, this room is more or less left up to just Jo King and me.

ChartZ Belatedly

@HyperNeutrino Personally, I support more ROs, as do at least 7 more people

Wasif

first find out who are most active

HyperNeutrino

@ChartZBelatedly wouldn't it be 8 since Bubbler couldn't have upvoted their own meta post? :P

ChartZ Belatedly

...yes

Wasif

@HyperNeutrino what are the eligibilities of being room owner

HyperNeutrino

16:15

also I misread that and thought you meant we should have 7 new ROs at first *facepalm*

ChartZ Belatedly

@Wasif The mods can find out who to appoint as ROs (preferably in an informal election) later, I think this is more of just a general interest check

@Wasif 100 rep across the network is the only mechanical requirement (that SE enforces)

Jonah

@OriginalOriginalOriginalVI, Thanks. How about this one?

New Sandboxed Posts

0

A: Sandbox for Proposed Challenges

Create a C program that is less than 120 characters the produces the most ASM possible. This limit does not include the def of main, or including headers. If a function is called the chars in the function count toward limit. The same goes for macros. The compiler used will be GCC 10.2 -O3 targeti...

Wasif

what are the main tasks of room owners?

HyperNeutrino

At this point I mostly just want to see if there are actually any people who oppose it or any reasons to not have more ROs, since the only reason we haven't run into issues is because I'm up way too late and this room is very non-problematic :D

@Wasif On TNB, the main function is to enforce the chatiquette. Things that are policy violations / rude/abusive can be handled by mods / 10k users by just flagging, but flags shouldn't be used for things that are specific to this chat room's culture/etiquette, so ROs enforce those.

ChartZ Belatedly

16:18

@Wasif ~~Mainly to keep the room "tidy". Cleaning up any star spam, kicking disruptive users, stepping in when the conversation becomes inappropriate for the room, enforcing the chatiquette, that kinda thing~~ What HN said

HyperNeutrino

Again, just like moderators, the ideal scenario actually sees ROs doing as little as possible, they're mostly just to handle problematic users, which fortunately we see few of here.

ChartZ Belatedly

Mother Meta guide for ROs

HyperNeutrino

wait ROs can kick ROs? lol

i wonder if ROs can kick themselves

Wasif

@HyperNeutrino try kicking Jo King XD

HyperNeutrino

@Wasif mods can't be kicked lol, and also he hasn't talked here in the past 24 hours

also he and I both aren't technically ROs, btw lol

ChartZ Belatedly

16:23

The current ROs

Wasif

oh I see

ChartZ Belatedly

CJY is still an RO despite their last message here being a month shy of 5 years ago

Redwolf Programs

I'd support more room owners, I don't think we really need them but it can't hurt

HyperNeutrino

wait, Dennis is still active in chat (as of "last seen", apparently within the last minute) :D

he hasn't sent anything in over a year, i hope he's doing well

Wasif

@HyperNeutrino any relative of him visiting?

HyperNeutrino

16:29

@Wasif hm, wdym?

ChartZ Belatedly

@HyperNeutrino He's generally "last seen" for under a minute most of the time, especially in talk.tryitonline

HyperNeutrino

Oh okay, I see.

ChartZ Belatedly

But tbh, even if he's only up to checking chat every so often, I'm fine with that. Small steps is the best way to help mental health issues

5

pxeger

ChartZ Belatedly

That's a pin :P

HyperNeutrino

16:30

0/10, no freehand red circle.

pxeger

ahh

ChartZ Belatedly

Means HN specifically pinned it to the starboard to make sure it stays there

pxeger

that's not very good UX

HyperNeutrino

@ChartZBelatedly yeah, totally agree

yeah a pin icon or something might be better. /shrug/

it means I (and any RO) can star their own messages :P

ChartZ Belatedly

There have been a couple instances in the past year where something's broken with TIO and it's gotten fixed pretty quickly after we let Dennis know in talk.tryitonline, so I think he's at least up to fixing major bugs with it

@HyperNeutrino IIRC they used to use a pin icon and people complained

pxeger

16:33

Why? Users complain about the darndest things

Wasif

when this pin feature was added

ChartZ Belatedly

It's been around since chat has

Bu given that only ROs and mods can do it, and it's usually used for announcements, we haven't had anything pinned for a while

Wasif

@ChartZBelatedly i haven't seen anyoneto pin messages yet

HyperNeutrino

@Wasif it hasn't been used in this chat room for a very long time lol

ChartZ Belatedly

Actually, that's probably one of the biggest reasons I'd like more active ROs: pinning accountments

Wasif

16:35

@HyperNeutrino since Dennis was mentally ill for long time, it was a wild guess

ChartZ Belatedly

E.g. we've normally had the "Best Of" posts pinned

HyperNeutrino

@Wasif ah. well I wouldn't know even if he did have relatives over

@ChartZBelatedly based on how featuring has gone, i wouldn't be surprised if pinning Best Of caused it to be stuck pinned for a few months, lmao

it's finally gone (from featured)

ChartZ Belatedly

\o/ Finally :p

pxeger

I finally figured out what was causing all my Google searches to hang until I manually force refreshed: HTTP 3

Firefox/Google/whoever is at fault need to fix their shit

Wasif

Today I was having a huge amount of network problems (and still having now), after a moderate storm in our region. I wonder how the storm affected internet bandwidth and speed

pxeger

16:52

I'm increasingly getting the feeling that people genuinely think GitHub Pro is worth the money

What's the point, since private repos are free?

Original Original Original VI

What does GitHub Pro do?

pxeger

You can use some team-oriented features: code owners, required reviewers, more storage in GitHub Packages, more minutes for GitHub Actions

Original Original Original VI

I can't see HN's name for a single message

pxeger

but I've never found any of those to be a limitation before

Original Original Original VI

Oh ok

pxeger

16:53

@OriginalOriginalOriginalVI ??

Original Original Original VI

Sorry, I didn't mean for it to be so big

Is it just for me or can everyone not see HN's name unless they have a monologue?

pxeger

nope, just you I think

HyperNeutrino

lol, what o.O

Original Original Original VI

Hmm

I don't think it happens for other moderators

Wasif

17:09

@OriginalOriginalOriginalVI i can see his name in every messages, which browser/device you are using?

I am using Chrome v89 on Windows 10 build 2004

Original Original Original VI

I'm using Firefox 87.0 on Windows

pxeger

Firefox 88.0b6

Original Original Original VI

I've disabled all my userscripts, and I doubt uBlock is doing it, so maybe it's just a browser thing

pxeger

does it also happen in Private Browsing?

Original Original Original VI

Huh, not Firefox then

@pxeger Lemme check

Yeah, same issue there

Works alright in Chrome, though

Monica Cellio

17:31

@pxeger Thank you. I apologize for our failure to follow up, and I'd appreciate it if you'd report it again on the security portal (which is new and tied into our internal ticketing system). Thank you for following up, and, again, I'm sorry for the inconvenience.

Deadcode

17:43

Anyone want to review my proof? Last comment in Is that number a Two Bit Number™️?. @JoKing's proof had a mistake halfway through, so I fixed and it followed where that led me.

Oops, I spotted a mistake. I'll have to redo it from that point

never mind until I fix that mistake

Deadcode

17:58

done

Okay, posted the proof as a link in a comment there. The proof is even more interesting now after actually being fixed

HyperNeutrino

18:14

What's the proof for; no number exists that has exactly two digits equal to 1 and all other digits equal to 0 in both decimal and binary?

Deadcode

@HyperNeutrino That's what I just proved. The link is in the second-to-last comment of that question.

HyperNeutrino

cool, I'll take a look

Deadcode

Arrrrgh damnit.

His proof was correct in the first place. I miscorrected it.

HyperNeutrino

ah. rip :/

ChartZ Belatedly

Any feedback? (aka, is it clear enough to post?)

HyperNeutrino

18:25

lol, having mathjax must've be nice for this challenge

ChartZ Belatedly

It definitely makes things easier :P

I suppose I could've coped using HTML tricks like <sup> for powers, and bolding the math like Dennis did, but mathjax is 100% better :P

HyperNeutrino

also yeah, I think this challenge is good +1

mathjax/latex is extremely awesome

i recently just started using latex again for my math assignments instead of google docs equations because i decided to stop being lazy and actually figure out how to set up a document and it's been so nice

especially since i'm needing matrices more for my linear algebra class now

ChartZ Belatedly

@HyperNeutrino Just use excel, and put each character in a different cell :P

Positional math notation works like a charm :P

HyperNeutrino

@ChartZBelatedly ......... i have elected to pretend you didn't say anything

rak1507

just use APL

HyperNeutrino

18:29

wait

@ChartZBelatedly can you explain how 764'343 becomes ...76476431

am I missing something or is that just a typo

ChartZ Belatedly

That's a typo, hang on

HyperNeutrino

(and then also wouldn't it be 31 + 764'00)

@ChartZBelatedly absolutely beautiful

ChartZ Belatedly

@HyperNeutrino Yep. I used 764'343 as an example before realising having one where \$x\$ and \$y\$ have different digit lengths would be better

HyperNeutrino

oh okay, lol

something I'm a bit confused about

why is it 31+764(...+10^9+10^6+10^3+10^0) and not 31+764(...+10^11+10^8+10^5+10^2)

ChartZ Belatedly

So the \$k\$ in the exponent for \$(...+10^{3k}+10^{2k}+10^k+10^0)\$ is always the number of digits in \$x\$. The value of \$y\$ has no effect, as it's just added to the fraction formed from the converged value

Something to do with how p-adic numbers work, I think

HyperNeutrino

18:36

i'm just confused because ...76476431 is not equal to 31 + ...764764

which is what 31+764(10^(3k)),k in N would be

let me take a look at the wiki article

i've never seen this before

ChartZ Belatedly

> 123'45.6 = 45.6 + 123'00 = 45.6 + 100 × 123'

From the wiki article, I think that examples it best

So I think my example may be wrong :/

HyperNeutrino

well if we follow the conversion algorithm, x = 764, y = 31, z = 100, a = 9, w = 999, answer is y-xz/w = 31 - 764*100/999 = -733.[764]

ChartZ Belatedly

Yep, my example's definitely wrong

Deadcode

@Deadcode I meant his proof was correct at the step I thought was wrong. I still haven't figured out the very last step

ChartZ Belatedly

@HyperNeutrino 31 - 764*100/999 is -45.476 (or -45431/999)

HyperNeutrino

18:52

@ChartZBelatedly right, I must've put 1000 when i calculated it by accident

ChartZ Belatedly

So that mistake definitely happened cause I don't fully understand p-adic numbers :P

New Main Posts

2

Q: Calculate longest Stack Exchange streak

Introduction This challenge is inspired by the Meta Stack Exchange question The longest consecutive days streak; it turns out that the URL https://codegolf.stackexchange.com/users/daily-site-access/[user id], where the last number is your user ID (found in the URL of your profile) contains inform...

code-golf date

ChartZ Belatedly

Got some test cases prepared, I think going through them by hand is the best way

HyperNeutrino

19:10

@Deadcode so, not sure how far you've gotten, but I tried rewriting the proof from the start, and it's pretty straightforward to prove that x=a is necessary, at least unless I've made some serious mistake

gist.github.com/hyper-neutrino/3762a1e865b1ceeec8ab5e87d008c318

i am not certain this is correct but IDK if the fact that x=a will help with anything

Deadcode

@HyperNeutrino Okay, but I agree with @JoKing's proof that x=a and I think his version is simpler

I still haven't managed to complete it into a valid proof

his last step looks pretty bogus

ChartZ Belatedly

It is surprisingly hard to convert a/b into x'y, I think I'll write a followup challenge as well :P

HyperNeutrino

@Deadcode probably; I just decided to see if I could get somewhere and unfortunately don't think I got any farther

@ChartZBelatedly just brute force :P

Original Original Original VI

19:29

That's pretty easy, just "a/b".replaceAll(".+", "x'y") in Java.

ChartZ Belatedly

Ugh, I'm having to read research papers to try to figure out a method for this, this is just rude :P

pxeger

today I decided to swap my terminal and browser windows on my monitors and it is very unsettling

HyperNeutrino

19:55

If a/b has to be reduced, is this a bijection from Z^2 to Z^2?

it's surjective apparently, but is it injective? i doubt it

ChartZ Belatedly

I'm not sure

The wiki article "gestures" to the idea that all rational numbers a/b can be expressed as x'y, but doesn't give any proof or conversion method from a/b to x'y

HyperNeutrino

based on the forward conversion method, it seems to be implied that any rational number is the the sum of an integer and a rational number over 99...99

or rather the difference, but same thing really

does this work if x'y are exclusively non-negative integers?

Transcript for