The Nineteenth Byte

12:44 AM

> more or less

Zacharý

Let me guess, doesn't work for 0 or something?

1:27 AM

@xnor my guess: generating functions

1:43 AM

@orlp generating functions?

@ASCII-only yes

(what do you mean)

it's not short enough but something like this

quartata

Generating function

In mathematics, a generating function is a way of encoding an infinite sequence of numbers (an) by treating them as the coefficients of a power series. This formal power series is the generating function. Unlike an ordinary series, this formal series is allowed to diverge, meaning that the generating function is not always a true function and the "variable" is actually an indeterminate. Generating functions were first introduced by Abraham de Moivre in 1730, in order to solve the general linear recurrence problem. One can generalize to formal series in more than one indeterminate, to encode...

n=input();k=2**n;print k**-~n/~-(k*~-k)%k

that's 41 bytes

try it online

@ASCII-only bonus points if you figure it out :P

1:51 AM

@orlp wait, how did you get this

@ASCII-only that's the challenge to figure out :)

I already told you too

ah :|

generating functions :)

n=input();k=2**n;print k**n*k/(k*k-k-1)%k

@ASCII-only I'll be nice and give you the deobfuscated version

PhiNotPi

This might not be that interesting, but I finally got a good USB Wifi adapter for my laptop and have been basking in the ~100 Mbps wireless speeds I should have always had.

@orlp hmm. so it appears to basically be using the "solving for the generating function" part of this, where k^2-k-1 = (1-k-k^2)-1? i think? i still have no idea what's going on, will (probably) think about it more when i get home

Downgoat

2:35 AM

@feersum what do you mean by interact? Travis has debug mode which allows you to SSH

3:08 AM

Funky2 offers two methods of logical not ! and not, but with different operator precedence. I'm sure this will be useful somewhere.

@ATaco so like ruby

Maybe

I don't know Ruby

@ATaco yes. except afaik ruby does it with and/or instead

the alphabetical ones being lower precedence than most operators

I could theoretically do that with Funky2, but i'm not sure at what precedence I'd put the symbol ones.

@ATaco normal precedence

i.e. just higher than =/+= etc

3:16 AM

Hmm, Well, I think I won't touch it just yet.

@orlp ok so this has 22 alphanumerics, i think? so we need to somehow simplify the formula to get rid of three :thinking:

4:05 AM

@Downgoat Like testing a GUI app.

Downgoat

You can run UI tests with Travis

Ha ha um, let's make that QA-ing the GUI app.

Jo King

6:47 AM

@WW I made a literal "bwah?" noise when I saw +500 in my rep notifier. I didn't even realise you'd put a bounty for my quine answer?

W W

7:08 AM

Congrats, you definitely deserve it. Its definitely a hard task.

8:20 AM

[Pyth]: What's wrong with this program? pyth.herokuapp.com/…

Looks like that the online interpreter has some missing libraries.

8:41 AM

TIL: Javascript is optimized for looping through arrays in ascending order, giving a 15-20% speed increase compared to descending order

Neil

@ASCII-only If only ↖^↖⊕⊗θ→↑⊗θ↗⊕θ‖ＢＭ↓↙⊗θ→↓⊗θ⟲Ｃ↑⁴Ｊ⁰¦⁰v worked, it's 8 bytes shorter than the best two solutions so far.

8:59 AM

CMC: Given a list of integers, output a truthy value if the product of any 2 integers in the list is greater than the sum of the list, otherwise output a falsey value (any 2 distinct values can be used)

Adám

@Mayube [1,1,3] true or false?

@Mayube stackoverflow.com/questions/1340589/… ~

Fatalize

@Mayube Brachylog, 7 bytes: ⊇Ċ×>~+?

@Adám false, the highest product in that list is 1 x 3 = 3, whilst the sum is 1 + 1 + 3 = 5

Fatalize

10 bytes with a fork: ⟨{⊇Ċ×}>ᵈ+⟩

9:06 AM

Jelly, 7 bytes: ŒcP€Ṁ>S

Adám

@Mayube APL (Dyalog Unicode), 15 bytes 1∊+/<∘∊⍳∘≢↓¨⊢×⊂

@Neil :| oops

@user202729 interestingly enough, turns out for(i = x; i--;){} is slower than for(i = x; i > 0; i--){} by about 20%

@Neil hmm. actually i have no idea why i didn't implement rotatecopy for cardinal directions

9:53 AM

@Mayube well, depends on your engine obviously :P

10:12 AM

@ASCII-only hint

you know that $F(x) = \sum_{n=0}^\infty fib(n)x^n$

can you explain this?

>>> f=lambda x: x/(1 - x - x**2)
>>> f(0.001)
0.001001002003005008

10:37 AM

@ASCII-only same results in chrome, firefox and node

@Mayube what about edge :P

and old FF, and Safari

Does Pyth have cumulative sum? Or cumulative reduce without starting point?

I can get .u+YNtQhQ, but it's too long;

And sM._Q is (probably) too slow.

@ASCII-only I'm on linux, i don't have access to edge

11:03 AM

@Mayube Doesn't that run 1 extra iteration..?

Yeah, because i-- returns what i was, not what i is set to, an additional execution of the loop happens.

Neil

@ATaco no, you iterate from 4 to 0 instead of 5 to 1

(that is, the value of i is different inside the loop, but the number of iterations is the same)

Both cases use i = x, but the first, i-- includes 0, the second, does not.

@ATaco but excludes the upper bound...

because it decrements before the loop body

You are correct, my bad.

Well, then it's probably just implementation issues, because Javascript.

@ATaco no... it's just optimization for certain cases

@ATaco you do not know how optimized JS is

11:15 AM

You are correct, I don't.

(if you want to find out, check out mozilla/google's js engine blog posts)

lol

11:38 AM

um

hello

hi

FrownyFrog

hi

lol

I'm trying to make a progressive web app

New Main Posts

2

Q: Implementing a stack

I can't believe we don't have this already.. It's one of the most important data-structures in programming, yet still simple enough to implement it in a code-golf: Challenge Your task is to implement a stack that allows pushing and popping numbers, to test your implementation and keep I/O simpl...

lol

btw how come ppcg still looks almost like half a year ago

12:02 PM

@lol wdym

12:34 PM

How can JS even be optimized

You can't guarantee i is an integer

Or if it is, that it is small enough that i - 1 != i

dzaima

@feersum crazy people do crazy things.

Do people ever use asm.js idioms in hand-written Java Scripts?

Scrooble

unsigned long long long x;

It was worth a try...

1:28 PM

How does the Wolfram Language work on TIO? Is the language itself free to use?

dzaima

@BetaDecay Dennis got contacted by wolfram or whatever to add it

Oh cool

Thanks Mr Wolfram

dzaima

in talk.tryitonline.net, Oct 4 '17 at 23:20, by Dennis

@quartata They (specifically, Jesús Hernández from Wolfram Research) reached out via email.

Python can be so unhelpful sometimes

Why the hell does it not set s=[] each time?

1:43 PM

List is mutable.

No, that behavior is very helpful. For example, to implement Dodos' call stack.

The list is shared for all calls of the function.

You can do s=(), but then it can't be pop.

s=s[:] works

(I hope you know why)

tio.run/… is even shorter.

Yeah, I've hit something like this before

Make the for loop 1line is even shorterer.

And convert ..if..else.. to ..and..or.. .

Less efficient, of course.

@user202729 Unfortunately if I did that, I would have the exact same code as another person's answer

1:47 PM

Anyone know Pyth here?

@isaacg

Not pingable.

Q: Remove surrounding zeroes of a 2d array

@BetaDecay default values for function arguments are only evaluated once

and then return a reference to the same instance every time

since lists are mutable, you're just changing that same instance all the time

New Main Posts

2

This is a 2-dimensional version of this question. Given a non-empty 2-dimensional array/matrix containing only non-negative integers: $$ \begin{bmatrix} {\color{Red}0} & {\color{Red}0} & {\color{Red}0} & {\color{Red}0} & {\color{Red}0} \\ {\color{Red}0} & {\color{Red}0} & 0 & 1 & 0 \\ {\color{R...

code-golf array-manipulation

def f(p,s=()):
 for i in p:
  if i:s+=i,
  else:s=s[:-1]
 return s

that works

1:52 PM

@user202729 Have I done it right? tio.run/##y00syUjNTSzJTE78/z/N1jMtOiC/…

No.

Meh

reference.wolfram.com/language/tutorial/PureFunctions.html

That still doesn't help

Why? It says body&.

Note the &.

1:59 PM

ohhh

tio.run/##y00syUjNTSzJTE78/z/N1jMtOiC/…

Better.

Now Positive....

I've just realised what I did wrong

FrownyFrog

2:33 PM

@user202729 Kenny probably does

3:06 PM

[Pyth] Is it possible to make pf (preceding function) a composition of multiple functions?

JungHwan Min

@BetaDecay your code might work if you pad 0s around the input with ArrayPad.

A: What are some useful, undocumented Mathematica functions?

But it's almost uniform, not completely equal.

Not sure about that.

Funny post:

44

The following simulates Mathematica's behaviour after using it for more than 24 hrs. MathLink`CallFrontEnd[FrontEnd`UndocumentedCrashFrontEndPacket[]] Works as advertised! :D