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That fractal that's been up on my wall for years(chriskw.xyz)
500 points by chriskw a day ago | 33 comments
CliffStoll 18 hours ago | parent | next [-]

Outstanding work and a delightful read.

chriskw 18 hours ago | parent | next [-]

Thanks Cliff, it means a ton coming from you! The videos from you and all the other folks on Numberphile always inspired me to see the beauty in math growing up :)

speeder 8 hours ago | parent [-]

Please you two, make an awesome YouTube vídeo out of this. It is fascinating and beatiful and deserves a chance to viralize a little :)

sakesun 13 hours ago | parent | prev [-]

Wow

wistlo an hour ago | parent | prev | next [-]

This is so much better than reading the news.

Favorited—I'll be coming back to absorb more, as my aging semi-fluency in engineering physics and SQL doesn't help much with the notation I last saw in the 1980s.

nico a day ago | parent | prev | next [-]

Amazing insightful and thoughtful write up, thank you!

Loved the 3d visualizations

It reminds me of this thing I built some time ago while playing with recursive decimation to generate effects similar to fractals from any image

You can play with it here: https://jsfiddle.net/nicobrenner/a1t869qf/

Just press Blursort 2x2 a couple of times to generate a few frames and then click Animate

You can also copy/paste images into it

There’s no backend, it all just runs on the browser

Don’t recommend it on mobile

Iwan-Zotow 20 hours ago | parent [-]

Curious if it would work in 3D

nico 20 hours ago | parent [-]

Very interesting! I wonder what that would look like

Right now, roughly, the algorithm recursively divides the image by doing decimation (ie. picking every other pixel), and keeps the decimated pixels as a second image

Not sure how that algorithm would apply to a 3d data structure

Do you know how 3d objects/images are usually represented?

It would be cool to recursively decompose a 3d object into smaller versions of itself :)

Cogito 12 hours ago | parent | prev | next [-]

Thought I'd check the arithmetic for 2 two-digit numbers, and it works!

I expect 41+14 to be 12 (two right plus two up equals two right and two up).

Long addition in long form below uses:

'=' to show equivalent lines (reordering of terms (1+2=2+1), spliting numbers (41=40+1), adding single digits (1+4=22))

'->' for when the algorithm gives a digit

'<' for when we move over a column

    41+14
    = (40+1)+(10+4)
    = 40 + 10 + (1+4)
    = 40 + 10 + 22
    -> 1s digit = 2
    < 4 + 1 + 2
    = 22 + 2
    = 20 + 2 + 2
    = 20 + 41
    -> 10s digit = 1
    < 2 + 4
    = 0
    -> done
    == 12
[edit] Just noticed the article has two different numbering systems, one where 10, 20, 30, 40 are clockwise and one where they are anticlockwise. In both, 1, 2, 3, 4 are clockwise. My addition is on the second, where 10s are anticlockwise (this is what is used in the addition table).

It still works in the alternative system (14+21 should equal 12)

    14+21
    =10+20+42
    ->2
    <1+2+4
    =13+4
    =10+3+4
    =10+31
    ->1
    <1+3
    =0
    ==12
baq 10 hours ago | parent | prev | next [-]

This went much deeper and harder than expected. One has to admire the dedication.

Question to the author: what would you recommend to hang on my kid’s wall today?

chriskw 10 hours ago | parent [-]

I'm by no means a parenting expert, but my answer would be anything related to something they feel passion or wonder for in the moment. I snuck in a paragraph near the end about burnout. At the root of the problem for me was that I lost the feeling of fascination and curiosity I had for math and programming, and doing this write-up helped me tap into that feeling of childlike wonder that used to come easily.

taeric a day ago | parent | prev | next [-]

Holy cow, I was expecting a quick read. Wound up having to skim some, as I need to get some work today. Will be coming back to this to play with some. Really well done!

Tade0 8 hours ago | parent | prev | next [-]

> Deciding to delegate to a future version of me that knows more math

Relatable. Huge part of my decision on what degree to pursue was a list of problems (mostly linear algebra) I needed to solve, but didn't have the guidance (and internet connection) to.

CBLT a day ago | parent | prev | next [-]

Well written! Would you mind sharing how you came up with the "middle out" numbering system? I can never seem to come up with something this inspired when I'm doing math problems by myself.

chriskw a day ago | parent [-]

The post presents it a bit out of order, but it was mostly from realizing at some point that the way the fractal grows by a factor of 5, base 5 number systems, and the "spiral" mentioned in the post can all fit together. I also thought a lot about how to programmatically draw the fractal and a natural way would be to start from the middle and zoom out.

There's an apocryphal story about Richard Feynman about how he used to keep a dozen or so random problems in the back of his mind and made a little bit of progress on them every time he saw a connection, until finally he'd solve one and everyone would think he magically figured it out instantly. This was a bit similar except I'm not nearly at that level and I've only been able to do that for one problem instead of a dozen.

leni536 a day ago | parent | prev | next [-]

Got a bit nerd-sniped by this and came up with an L-system that fills out (I think) "the wallflower":

https://onlinetools.com/math/l-system-generator?draw=AB&skip...

edit: On second thought, this probably generates the other fractal, but I'm not sure.

leni536 6 hours ago | parent [-]

Found a space-filling curve for the wallflower:

https://onlinetools.com/math/l-system-generator?draw=ABCD&sk...

The previous one fills out the Koch island.

tcshit 18 hours ago | parent | prev | next [-]

Nice writeup! I was hoping to see a photo of the fractal on your wall.. Nice link to Knuth video that I somehow have missed.

leephillips 18 hours ago | parent [-]

Isn’t that it on the left in the last image?

tcshit 11 hours ago | parent [-]

Yeah, maybe it is. It would be cool to make it much bigger, frame it and put it on the wall. Or create a mosaic tiled artwork, similar to Knuth’s dragon curve wall.

chriskw 10 hours ago | parent [-]

Yeah, it's in the last image and in the thumbnail at very top (which I realize now is really hard to spot on mobile), intentionally not in the spotlight to leave space for the twist at the end.

https://chriskw.xyz/images/fractal/thumbnail.jpg

I think it would work perfectly as a mosaic eventually, but for the time being I'm perfectly content with the "rustic" 8x11 graph paper sized one taped to the wall. Currently planning to put up a slice of the orthotopeflower as a companion piece once I find matches for the colored pencils I used back then.

kragen 7 hours ago | parent | prev | next [-]

This is beautiful. Thank you.

867-5309 8 hours ago | parent | prev | next [-]

well, that escalated beautifully

Scene_Cast2 21 hours ago | parent | prev | next [-]

I wonder if something similar can be applied to get a dither pattern with built-in level of detail adjustment.

cess11 20 hours ago | parent | prev | next [-]

Nice writeup. The Heighway dragon of Jurassic Park fame is pretty neat too.

https://en.m.wikipedia.org/wiki/Dragon_curve

cies 10 hours ago | parent | prev | next [-]

I had this one up the wall (giant print) at a place I worked:

https://raw.githubusercontent.com/cies/haskell-fractal/refs/... [17MB, sorry Github]

It contains the Haskell code that produced it: https://github.com/cies/haskell-fractal

Especially the `sharpen` function was interesting to come up with (I used some now-offline tool to do curve fitting for me): https://github.com/cies/haskell-fractal/blob/master/fractal....

Fun little project. :)

entropicdrifter a day ago | parent | prev | next [-]

Kinda looks like a propeller

shermantanktop a day ago | parent [-]

Things with four arms that all curve the same way unfortunately tend to look swastika-ish.

leni536 a day ago | parent | next [-]

The the arms of the author's "wallflower" fractal don't seem to curve, as opposed to the other, similar fractal (quadratic von Koch island). Which can be explained by each iteration adding a mirroring.

winnit 8 hours ago | parent | prev [-]

The unfortunate thing here is that the swastika was appropriated by a genocidal regime. The symbol still has a totally different life in India and Japan.

bdamm a day ago | parent | prev | next [-]

That was fun.

matt3210 12 hours ago | parent | prev | next [-]

Now make a tiling game engine that uses these!

mathfailure 4 hours ago | parent | prev [-]

Too much math.