The Nineteenth Byte

Bálint

22:00

I updated my site with 4 more javascript "demos": mcdorli.github.io

And yes, that's the simplest UI I could create

New Sandboxed Posts

-1

A: Sandbox for Proposed Challenges

Calculate Hello World! popularity-contest hello-world underhanded Your goal is to calculate the simple string "hello world" or any other variant. Rules You may not use the characters in this set (inside your code): hHeElLoOwW rRdD!, in any form (character codes, hex codes, etc. not allowed) ...

aditsu

results are in.. rank 157

El'endia Starman

@Bálint I don't get the quadtree one, and also there are at least two typos.

Bálint

@El'endiaStarman I made this whole thing in like 30 minutes, I go, correct the typos

Also, a quadtree is a 2d version of octree

Octree

An octree is a tree data structure in which each internal node has exactly eight children. Octrees are most often used to partition a three dimensional space by recursively subdividing it into eight octants. Octrees are the three-dimensional analog of quadtrees. The name is formed from oct + tree, but note that it is normally written "octree" with only one "t". Octrees are often used in 3D graphics and 3D game engines. == For spatial representation == Each node in an octree subdivides the space it represents into eight octants. In a point region (PR) octree, the node stores an explicit 3-...

El'endia Starman

I know what a quadtree is. I don't know what the image represents.

Quill

22:04

@Upgoat I'd really rather not bother having to build everytime

Bálint

The image is just a random bitmap

Almost

There's a bias to the upper areas

El'endia Starman

I like the binary fractal tree demo the most.

Eᴀsᴛᴇʀʟʏ Iʀᴋ

gfycat.com/GreedyEminentGalah

El'endia Starman

@Bálint Yeah, I don't get that. To me, a bitmap is just an image, and a quadtree sections a 2D area into four smaller areas, recursively, and is used for various (spatial) optimization purposes. The obvious and huge gradient from top to bottom makes no sense, then.

Bálint

@El'endiaStarman Try setting angle to 2/3, and angle offset to 1/2 and you get another fractal

@El'endiaStarman The gradient is there, to make bigger clusters instead of just 1 or 2 2 * 2 ones

El'endia Starman

22:08

Yeah, but where does the quadtree bit come in?

Eᴀsᴛᴇʀʟʏ Iʀᴋ

Bálint

@El'endiaStarman After I have a random bitmap, I can optimize it by generating a quadtree around it

El'endia Starman

Optimize a bitmap? Huh? I thought that was basically just an array of color values.

Bálint

@El'endiaStarman Imagine it for a 10000 by 10000 image

Instead of literally just storing 1000000000 values (wich can be stored in around about 125000000 bytes), it can be stored in ~10000bytes

flawr

@Bálint Cool stuff!

Bálint

22:12

Because a quad-tree only needs 5 values, an x, a y position, a width, a height and a color

El'endia Starman

Ah, I think I get what you're doing. The remaining problem is the heavy bias from top to bottom. I would expect the big(ger) squares to be evenly distributed, since that's what I think when I hear "random".

Bálint

@El'endiaStarman Again, it's just there for presentation, with a simply Math.random(), it wouldn't be as visible as it is right now

So, for example the top 64*16 pixels are almost always clustered together

With 4 squares, it's only 20 bytes to store it, without optimization, it's 128 bytes

El'endia Starman

What about placing a white square anywhere with probability 0.05? That'd be much more interesting.

Bálint

@El'endiaStarman You know what, I make it to use user input

So, where you click, it becomes a white square

El'endia Starman

That'd work too.

Eᴀsᴛᴇʀʟʏ Iʀᴋ

22:22

i.imgur.com/AW489A8.gifv

Bálint

@EᴀsᴛᴇʀʟʏIʀᴋ I never saw a cat, wich wasn't immedialitely scared, when he/she saw another cat.

Eᴀsᴛᴇʀʟʏ Iʀᴋ

...

You haven't met nice cats.

and @Upgoat have you been teaching @Bálint how to spell?

Bálint

@EᴀsᴛᴇʀʟʏIʀᴋ Spell what?

@El'endiaStarman mcdorli.github.io/quad_tree/index.html

Upgoat

@EᴀsᴛᴇʀʟʏIʀᴋ it's probably just because @Bálint doesn't even have hands. It must be difficult to type as a loading sign

El'endia Starman

@Bálint That's more like it! feature-request Click-and-drag to flip multiple pixels. feature-request Click on white pixels to flip to black.

flawr

22:28

@El'endiaStarman I agree, flipping back would be cool=)

aditsu

flawr

@aditsu Are they on a treadmill or what???

aditsu

nah, the camera is just following them

flawr

@Bálint I think you should also enable flipping to different sizes

Bálint

@El'endiaStarman @flawr mcdorli.github.io/quad_tree/index.html <- I added dragging and flipping

2

El'endia Starman

22:34

@Bálint Awesome!

Bálint

@flawr square brush or circle brush?

El'endia Starman

I would think square.

Helka Homba

@Bálint that is cool

flawr

@Bálint Square! Thats really cool!

Helka Homba

@Bálint It'd be cool if you could right-click and reset the corresponding lowest quad square (I guess double clicking does this so nvm)

Bálint

22:38

@flawr Ok

flawr

You know, when you have a bigger square that consists of smaller squares of different colour, it would be cool if you could reset that back to black or white (my suggestion: left or right click, or some toggle switch)

OOOhh, dragging also works with black, if you already begin with a white square=)

Helka Homba

"white square" and "region" counters would be nifty

xnor

@Bálint very cool! are you recalculating the quad tree at each step or updating for each change?

El'endia Starman

Funny how one simple change in demoing a quadtree suddenly has people going "OMG SO COOL!". :P

Bálint

@xnor For each change, it's actually pretty heavy on the CPU

@El'endiaStarman :P

flawr

22:43

@El'endiaStarman I'm waiting for the 4D hexadec tree :D

Lynn

@CᴏɴᴏʀO'Bʀɪᴇɴ Your comment on my answer is obsolete now! :D

But, I’m not sure what you meant

Cᴏɴᴏʀ O'Bʀɪᴇɴ

oh

El'endia Starman

I was feeling artsy.

3

Cᴏɴᴏʀ O'Bʀɪᴇɴ

I meant, "why use chars with code X instead of numbers with value X"

Lynn

I think it’s parse(Int,"12345"[t]) versus Int("#####"[t])

And the latter is shorter. But maybe there’s Julia things I don’t know about

Cᴏɴᴏʀ O'Bʀɪᴇɴ

22:50

oh :P

I missed that

Lynn

Now I encode [4,5,2,3,3,1,5,4,1] as a base 6 number!

Let’s see if it can be shifted base 5.

Nope, doesn’t look like it

Ashwin Gupta

anyone familiar w/ cpp?

Why can't I do this:

class Coin {
	public:
		int value;
		void setValue();
};

void Coin::setValue() {
	this.value = 3;
}

this.value is the problem, won't let me use this

flawr

What error do you get?

Intuitively I'd use this->value because I think this is a pointer to the current object.

Lynn

That sounds right

flawr

But if you do not use value as a new variable within setValue you should also be able to type just value instead of this->value

Lynn

22:59

FWIW, I get a perfectly readable compiler message about this from gcc O_o

prog.cpp: In member function 'void Coin::setValue()':
prog.cpp:10:7: error: request for member 'value' in '(Coin*)this', which is of pointer type 'Coin*' (maybe you meant to use '->' ?)
  this.value = 3;

flawr

Yay, I still remember the stuff, even though I had an exam on this like 3 days ago =D

El'endia Starman

I like the accuracy of "even though".

Lynn

Fact: 3 is actually an odd number of days.

flawr

@Lynn Depends on what ring you consider 3 an element of XD

Sorry, every now and then I just have to give in to the urge to show that I'm not a CS guy :D

Bálint

@flawr Done, you can change brush size: mcdorli.github.io/quad_tree/index.html

2

Lynn

23:05

I can’t think of a ring in which anything you’d call 3 is anything you’d call even

flawr

Z/nZ where n is an odd integer

Lynn

But do “odd”/“even” make sense, then?

flawr

even just means divisible by two

Lynn

Wikipedia gives a pretty cool generalization: en.wikipedia.org/wiki/…

flawr

but true, odd might be not very well defined

Lynn

23:09

> Let R be a commutative ring and let I be an ideal of R whose index is 2. Elements of the coset 0+I maybe called even, while elements of the coset 1+I maybe called odd.

(Huh, how do you know 1 is even a thing)

flawr

You usually consider rings with ones in ring theory.

Lynn

(I guess it’s abuse of notation and they mean R\I?)

Ohh. Yeah

Otherwise they’re rngs, which is the best term

flawr

@Lynn Random Number Generator? But how do you even pronounce rng?

Never heard that before, but I love the idea=)

rng might be dothraki language

Lynn

The article says it’s like, rung

But it’s fun to just say /ɹŋ̩/

flawr

feature-request more words without vowels

=P

@Bálint This is soooo coool, can you now make a scroll-wheel-listener (if such a thing exists?) for changing the size?

El'endia Starman

23:15

@Bálint Super!

flawr

@Bálint This reminds me of the adaptive grid methods we had to use for fluid dynamics simulations=)

how dizzappointing

pigeonhole principle: If you have 4 pigeons and 5 holes, you shot one of the pigeons at least twice

Cᴏɴᴏʀ O'Bʀɪᴇɴ

23:32

This is good

Alex A.

Very nice white square

Eᴀsᴛᴇʀʟʏ Iʀᴋ

yes

almost as nice as @LegionMammal978's

El'endia Starman

@flawr Oh that's so cool! I can't get dizzy either since my semi-circular canals are malformed, so I don't have a functioning vestibular system.

Eᴀsᴛᴇʀʟʏ Iʀᴋ

lol

El'endia Starman

Y'know those "spin around a baseball bat with your head on it and then try to run straight" games? Never posed a problem for me.

Eᴀsᴛᴇʀʟʏ Iʀᴋ

23:40

"I can't get dizzy because my body is messed up"

aditsu

@El'endiaStarman what? are you able to walk?

El'endia Starman

@aditsu Yep, because I also have vision and proprioception!

aditsu

how can you keep your balance without a functioning vestibular system?

El'endia Starman

Apparently there's a theory of balance that says you need at least two of the following three balance systems: vestibular, visual, proprioception.

aditsu

can you stand on the toes of one foot?

El'endia Starman

23:42

I think it's especially my proprioception, since I often do stuff like stand on one leg and use the other for counterbalance as I reach out to put down or pick up something.

@aditsu Just tried that and yes I can.

aditsu

but only with your eyes open?

El'endia Starman

...lemme try that.

aditsu

maybe try the whole foot first

El'endia Starman

I could barely stand on one foot, period.

aditsu

huh, fascinating

El'endia Starman

23:50

Oh, Wikipedia has this:

> Somatosensory system: senses of proprioception and kinesthesia of joints; information from skin and joints (pressure and vibratory senses); spatial position and movement relative to the support surface; movement and position of different body parts relative to each other

As one of the three components of one's ability to balance.

Oh, also, I have successfully stood on a slackline for more than three seconds in the past. :P

aditsu

I guess when one sensor is failing, the body learns to make use of alternatives with great accuracy

El'endia Starman

Good ol' brain plasticity!

aditsu

also, is the vestibular system issue related to the hearing problems or a separate thing?

my colleague who had a cochlear implant is able to ride a unicycle, and learned to ride a caster board in no time

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