The APL Orchard

3:49 AM

{({⊃(,,⍤0)/↓(⌽@1)2(2÷⍨≢⍵)⍴⍵}⍣{⍺≡w})w←2(⊥⍣¯1)⍵}201

How do I find out how many times ⍣ loops?

4:00 AM

@Razetime A classic way is to use a local variable and increment each time the loop runs.

hmm ok

But I think dfns.traj could work in your case, as you're running until you encounter the original input again

oh so it needs to be local local

not in the function

@Bubbler I think limit works better

oh nevermind that's just ⍣≡

No, this setup should work: {i←0 ⋄ i⊣{i+←1 ⋄ one_iteration}⍣{end_condition} start_value} if you want to return the iteration count

cool

lemme see if traj is any shorter

doesnt seem to work here: Try it online!

(Extended)

4:15 AM

@Razetime You used wrong input section there

ah yes my genius shines through

But yeah, Extended is known for being quirky with assignments

Try it online!

So it does run 4 times

just that i displayed at the end is 0

But it does work in non-Extended

though other parts are a bit verbose

Try it online! traj is very golfy

Try it online! 32 with a full program

4:23 AM

Yes, it's pretty useful in various occasions

Also 29

oh, monadic ⊤

cool, we beat CJam

CJam is ASCII-only, so it's at least occasionally beatable with APL

Then there's Pyth😁

Pyth is almost unbeatable, so it's one of my hated golflangs

ah well

its really good for complex challenges

4:45 AM

am I doing something wrong here? Try it online!

@Razetime 2|≢⍵ is a scalar, and if you try 2 ¯1⍴ on it, ⍴ can't determine the length of the second dimension

oh yeah

Need to use :

There

Good.

now it should work for any \$n\$

yay no mathjax

You can't mathjax in chat

it's status-bydesign

4:52 AM

that's a funny tag

or status-declined

I like the bydesign more

3 hours later…

8:02 AM

@Razetime What does traj do?

APLcart says "function limit trajectory" but what does that mean?

Adám

@RGS You know you can click the (?) icon?

@Adám Erm, I completely forgot there was a docs link.

@RGS It iterates the left operand function, collecting intermediate results, until it encounters an already seen value.

Yes, traj is short for trajectory. Understood.

8:19 AM

traj stands for TRApped in Jail

@Razetime If you say so :p

wow now I'm teaching

2 hours later…

Elias Mårtenson

10:12 AM

@rak1507 I'm currently working on ⌽. Turns out there are several bugs in its implementation.

2 hours later…

rak1507

11:58 AM

@EliasMårtenson cool

3 hours later…

3:10 PM

M⍋s⊤∊r⍳ng Dy⍋⌊○g ⍋P⌊

^ New suggested title for the "Mastering Dyalog APL" book.

rak1507

Beautiful

˜⍺⌈~∊⍴⍳⊤∇ Î↑⍺⎕○∇ Å⍣⌷

a literal translation

I get this: ∥⍺⌈~∊⍴⍳⊤∇ ∙↑⍺⎕○∇ ´⍣⌷

With Adám's keyboard.

hmm I'm using the mac layout

1 hour later…

4:33 PM

Helloo

I'm trying to port this algorithm: codegolf.stackexchange.com/a/168542/80214

Is this right? Try it online!

the main plotting part is {P5.G.ln {(2○⍵),1○⍵}1 k×⍵×a}¨⍳n

4:46 PM

@Razetime ln takes as arguments x1 y1 x2 y2 …, whereas you're giving x1 x2 y1 y2

you're also drawing everything in the range ¯1…1, so only 1 pixel is visible

hmm ok

{P5.G.ln {(2○⍵),1○⍵}¨1 k×⍵×a} for x1 y1 x2 y2

then {P5.G.ln 30×{(2○⍵),1○⍵}1 k×⍵×a} maybe?

also seems that python code has swapped n and k

ok small question

@Razetime with the ¨ and ↑ after the dfn because ln doesn't expect a nested argument (and also 30+ otherwise ¾ will still be off-screen)

I think {P5.G.ln {⍵○1 k×⍵×a}¨2 1} is cleaner?

then ↑ right?

hmm nothing is showing up

4:57 PM

@Razetime that creates a matrix [x1 x2 ⋄ y1 y2] whereas we need [x1 y1 ⋄ x2 y2]

also you're using ⍵ for both the iteration and sin/cos there

{P5.G.ln↑30+{(2○⍵),1○⍵}¨1 k×⍵×a}

oh yeah thats terribly wrong

@Razetime missing 30×, but that works

@Razetime and you can definitely do something better than {(2○⍵),1○⍵} there as ⍵ is a scalar

2 1 ○ ⍵

yep. and 2 1∘○¨ for golfing

5:01 PM

also: you can golf a←2×○÷n, and then inline it into the function

actually we dont even need that definition

@dzaima and since this is dzaima/APL, 2 1○ᑈ also works

also 30+30× → 30×1+ :| (also no space needed between 1 and k)

is there any shorter way to draw a circle?

like, are there aliases for 'center'P5.G.circle 30 30 60 60?

{P5.G.ln↑30×1+2 1○ᑈ1 n×⍵×2×○÷k}¨⍳k also this is what I finally got

@Razetime remove space between 1 and n; you can also golf 2×○÷k by 1 char

@Razetime the final 60 isn't doing anything

and with no left arg, the 3rd argument is the radius, so P5.G.circle 3⍴30 works

{n←⍺⋄P5.G.circle 3⍴30⋄{P5.G.ln↑30×1+2 1○ᑈ1n×⍵×2×○÷k}¨⍳k←⍵}

so this can be the final function

5:16 PM

15 mins ago, by dzaima

also: you can golf a←2×○÷n, and then inline it into the function

a isnt even in the function

it's not needed

@Razetime i meant the "golf" part. you already inlined it

ohhh

○2÷n?

yep