The Nineteenth Byte

A: Sandbox for Proposed Challenges

@NickClifford Pardon me for not understanding, but what exactly do you mean? Do you want to match the first and third as in abc"abc"abc, but not the second (or something similar)?

Posted the domino challenge. If I don't get Hero of Time for this I will be extremely disappointed in the SE team

Ah shoot, I missed the "7:00 pm" requirement. nevermind...

New Sandboxed Posts

1:22 AM

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Ungolf my tinylisp code code-golf parsing whitespace lisp balanced-string I like golfing in tinylisp: (d M(q((x)(i x(i(disp x)0(M x))0 But I also like posting explanations with nicely formatted code: (d M (q ((x) (i x (i (disp x) 0 (M x)) 0)))) Can you help me generate the u...

@NickClifford so something like: regex101.com/r/EfXDJn/1?

New Main Posts

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Q: Draw me a domino

Challenge Given two digits 0-9 as input, output a domino (from the double-nine domino set) with these number of pips (dots) on the two faces. The ten possible faces look like this (separated by pipes): | | o| o|o o|o o|o o o|o o o|o o o|o o o | o | | o | | o...

Nick Clifford

@ETHproductions yes, pretty much. in the case of Ohm, I want it to match newlines only when they're outside of quotes

@Downgoat I think that should work

although actually there's something I haven't thought about

in Ohm, there's multiple string delimiters

and I wonder if it's possible to match the newlines iff they're not inside a matching pair of only one delimiter?

wait yeah @Downgoat's regex does work for that if I modify it a bit

well thanks for the help

1:41 AM

I hate python. I probably have inconsistent tabs and spaces everywhere in my MY code ... ugh! And ETH is back!

> Don't use The Nineteenth Byte as a dumping ground for your thoughts or actions. Consider whether a topic would be relevant to others before talking about it. We're here to have discussions, not to listen to someone's stream of consciousness.

Never heard that one before

Leaky Nun

thinks to himself but stream of consciousness is interesting

...

2:39 AM

No freaking way, I earned Hero of Time anyway :O

Huh>

The answer must have inferred the PM from something

Oliver

@ETHproductions nice challenge

thanks :)

I fear I may have been too liberal with the output format, as binary arrays will probably be shorter in most languages than actual ASCII-art

Anonymous

@ETHproductions Nepal is UTC+5:45, so posting at :15 works.

Anonymous

2:50 AM

However, there are no +:15 time zones, so only :00, :15, and :30 work

Anonymous

And sometimes :15 and :30 don't work because none of the time zones align with midnight

@Zacharý in that case please read chatiquette

Anonymous

CMC: Output the number of minutes it is until it is exactly midnight in any time zone on this page. You may optionally take the current time as input. The output may be rounded either up or down, at your discretion.

Anonymous

Alternate wording: output how many minutes you should wait before posting if you want Hero of Time ASAP.

@Mego I meant to get the hat, the thing here is that the answer explaining how to get it says you need to post at 7:00 pm, and it was 7:00 am in Nepal

Anonymous

2:59 AM

@ETHproductions Huh, that's right. Weird. It was 15 minutes past 7 pm in CST

3:53 AM

ಠ_ಠ There haven't been any good maths challenges recently

@cairdcoinheringaahing How would you define "good"...?

@user202729 Fairly easy (20-30 answers), not involving arrays.

Easy challenges are not always good.

They are for me

“¤noṛ... what a coincidence.

4:00 AM

What's the coincidence?

From this answer.

Ok... anyone else working on next OEIS sequence?

@Adám [[], [[]], 0]

@user202729 Correct me if I'm wrong, but this seems to be incorrect. The B is part of the ŒB, rather than being the "to binary" atom.

@cairdcoinheringaahing Not that B, the other B.

@user202729 In the second solution?

4:08 AM

Yes.

@user202729 Doesn't look like it. Looks to be a 2017 only challenge :/

I just downloaded Java 1. The installer UI looks old...

@cairdcoinheringaahing Who is/are one oeis after another room owner(s)?

And why are the pinned messages still starred, while it lost the pin status?

quartata

When you pin a message, you also star it. The pin is temporary, but stars are permanent

So RO can star their own message...

quartata

yes I suppose

bushdid911

4:29 AM

Has anyone here used Trajedy before? It seems really mathy

@user202729 Me

@quartata Unless they're deliberately removed

To be fair, this one is no (or only slightly) harder than the domino sequence...

Primitive element (finite field)

5:10 AM

Hey if I have a finite filed will there always be a element that generates the field under multiplication? If there is I can make a very nice golf.

In field theory, a primitive element of a finite field GF(q) is a generator of the multiplicative group of the field. In other words, α ∈ G F ( q ) {\displaystyle \alpha \in \mathrm {GF} (q)} is called a primitive element if it is a primitive (q−1)th root of unity in GF(q); this means that all the non-zero elements of G F ( q ) {\displaystyle \mathrm {GF} (q)} can be written as ...

@WheatWizard I don't think so (if it is not cyclic)

A: Finding a primitive element of a finite field

I forgot about non-cyclic finite fields for a moment there

I do only mean cyclic

3

Pick an element and compute its powers. If these cover all nonzero elements, you have found a primitive element. Otherwise pick an element that you did not cover and start over again.

This answer is super helpful

I think F_4 doesn't.

Naive algorithm, but for codegolf the simpler the algorithm, the better.

That's the field extension of the Klein 4 group? I've forgotten the notation

Z/4Z.

(the group of integers modulo 4)

5:23 AM

Oh, lemme think

I don't think that is a field

It is.

What is the inverse of 2?

Oh... so it isn't.

So, only consider fields F_p[x]/m(x), as in the question, where p is a prime.

I'm pretty sure Z_p is only a field if p is prime.

Yes that's correct.

testing some fields

5:29 AM

Same :)

If n is not prime, take n = ab (a,b > 1). Then in Z_n, a*b = 0, so a,b are zero divisors, don't have multiplicative inverses, etc.

@user202729 Try it online!

Hm... what it does? I don't know Haskell.

For each prime p it finds all the primitive elements in Z_p. The output is a list of primes and their primatives

typo: primitives. / Ok.

5:40 AM

- nevermind

By Wikipedia it's true.

What is?

Try it online!

now my output is human readable.

That all Z_p multiplicative fields (\0) are cyclic.

They're cyclic under addition

5:45 AM

Multiplication too.

> The structure theorem of finite abelian groups implies that this multiplicative group is cyclic, that is, all non-zero elements are powers of a single element.

Those are the primitives, though (I missed the \0)

Is this for the OEIS challenge?

No I'm just working with some prolog code, would be nice if I could find primitives effeciently

@WheatWizard I was just trying to remember if there's a better way to determine the primitives than brute force. You can calculate how many there are efficiently (en.wikipedia.org/wiki/Primitive_element_(finite_field))

Yeah, I linked that a little while ago

It seems like this is a hard problem

arxiv.org/pdf/1304.1206v4.pdf

Yeah, I just found the same paper through math.se

It's not often obvious what's easy or hard to do in algebra (to me)

5:53 AM

If it involves finite fields a good bet is always hard.

Finite fields are used in cryptography because of their hard to compute properties IIRC

Mostly discrete log, I think.

6:16 AM

@WheatWizard I see some indication that maybe the difficulty is in finding a primitive element for Z_p with p so large that (p-1) can't be factored. There's an implication that with the factorization of (p-1) in hand, there's a fast way to find the primitives. I don't know what it is

@WheatWizard You might want to check out johnkerl.org/doc/ffcomp.pdf S2.5

nice

I think it might apply to what you're doing. I didn't read it carefully enough to say for sure, but it's written at a very convenient level. I'll stop trying to help, but let me know if you find a better method?

A: Sandbox for Proposed Challenges

At this point what I was doing is completely out the window.

I'm just intrigued

Esolanging Fruit

7:53 AM

I just realized that regexes form a ring...

Potato44

11:45 AM

@EsolangingFruit With which operations? Alternation and repitition?

Wait that doesnt make much sense, repition is a unary operator. I think I was thinking of concatenation.

Soaku

1:26 PM

I got an idea for challenge, and I thought that it would be cool to name it "The ting goes [skrrrahh in BF]", but it's gotta be quite long... Anybody got a better idea? xD

Soaku

2:00 PM

why do I have this icon here? lol, I changed it long time ago...

New Sandboxed Posts

2:34 PM

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The ting goes >+++.--------.+++++++...<+.+++++++..! popularity-contest kolmogorov-complexity The title is actually valid BF code, but only if you initialize the tape with hex 50 60. Well... not even sure if that's correct. One of the latest memes is the song by Big Shaq, "Mans not hot". When...