A shower thought turned into a Collatz visualization

A shower thought turned into a Collatz visualization(abstractnonsense.com)

137 points by abstractbill 363 days ago | 26 comments

gpm 363 days ago |

> The points look quite uniformly distributed to me. If I squint, then maybe I can see some structure, but it's hard to describe and I could be imagining it.

It doesn't, these points look like what happens if you ask someone who doesn't know what a uniform distribution looks like to generate a uniformly distributed set of points though.

Here's what an actual uniform distribution looks like... much less "uniform": https://claude.ai/public/artifacts/00549caf-2ec1-4803-b909-6...

Credit to the book "Struck By Lightning" for making me aware of this fact, many years ago now. Disclaimer that the author is a family friend.

Edit: I misunderstood what was being plotted in the article, and as a result had claude plot random instead of evenly spaced X coordinates. It doesn't change my point, but this version has the appropriate distribution to compare to (evenly spaced x, uniformly randomly y coordinates): https://claude.ai/public/artifacts/a04a3023-25d3-4d99-889d-a...

mkl 363 days ago | |

"Uniformly distributed" doesn't just mean sampled from a uniform distribution. It also means evenly spaced, as is the case here. It reminds me of Poisson disk sampling. Here's an article about Poisson disk sampling that uses "uniform" in the sense the author is, and also compares to the uniform probability distribution: https://medium.com/@hemalatha.psna/implementation-of-poisson...

gpm 363 days ago | | |

Really the germane point isn't that it isn't specifically a uniform distribution, but that there is clearly structure to the distribution of those points. The locations are visibly not a set of IID random variables, because IID random variables don't space out that... uniformly.

That said, while I agree "uniform" not followed by an inflection of "distribution" has many other meanings, I do not agree that it the context of math, in a context where there is a standard uniform distribution, and without other relevant context, "uniformly distributed" can properly be understood to mean anything other than distributed via the standard uniform distribution.

willrftaylor 363 days ago | |

For what it's worth, I thought "uniform" was a fine description - as you zoom out, the pattern looks more organised and less random. That is a property of uniform distributions.

https://bookdown.org/kevin_davisross/probsim-book/sec-linear...

pepinator 363 days ago | |

Irrational rotations of a torus are uniformly distributed and closely resemble the image from the blog. The images you linked, on the other hand, are random sequences with positive entropy (which are also uniformly distributed). Confusing these two things is what happens when someone without the necessary expertise tries to sound smart.

WithinReason 363 days ago | |

The author invented a new low discrepancy sequence generator

manwe150 363 days ago |

As for the randomness, I have wondered if Collatz sequences are somehow related to the properties of a common prng with multiplier 3/2, infinite length state vector, and mod 2 on the output with this formula: https://en.m.wikipedia.org/wiki/Linear_congruential_generato.... I assume this could be part of what makes the conjecture both interesting and difficult and beautiful.

Very cool to see there is some patterns hiding in the randomness too!

ginko 363 days ago |

Talking about shower thoughts on Collatz visualizations..

A while ago I though of a way of structuring the collatz orbits by arranging integers in a 2d grid with odd numbers being arranged along the X axis and multiples of the power of two along the Y axis.

https://gist.githubusercontent.com/ginkgo/13121db56b65b1237e...

So essentially any odd number n and all numbers n * 2^m belong to the same group of numbers that eventually reduces to n. All that's left is the 3n+1 orbits which are shown as lines from the odd numbers.

This reveals quite a bit of structure (IMO) especially only every second odd number goes to an orbit reducing to an odd number larger than it (and it's always in the form n * 2^1) all the other orbits every 4th, 8th, 16th odd integer immediately reduce to an odd number that's lower.

Anyone seen an arrangement like this for the Collatz orbits?

gpm 363 days ago | |

Just wanted to chime in and say that's a really interesting visualization of the conjecture, I haven't seen it before (and I have wasted more than a few hours on this problem).

bawana 359 days ago | | |

try this visualization https://gist.github.com/bwanaaa/4c77b33311916b230c8b1891bab4... just open it in collar and the 3d graph appears

bawana 362 days ago |

Here is a python script that plots on the Z axis - each number through an entire Collatz cycle until the result of 1, on the X axis - the number of cycles needed to get to 1, on the Y axis - add 1 for odd numbers, subtract 1 for even numbers. https://gist.github.com/bwanaaa/4c77b33311916b230c8b1891bab4...

You can open it in colab to visualize it. You can change the range of integers by modifying line 33 in the function def generate_all_sequences():

Interestingly, it seems there are more odd numbers than even ones in a collatz sequence as all graphs tend to the positive Y axis. All numbers tend to generate 3x as many odd results as even and they all seem to do this at this same rate.

In the first 750 integers, the number 703 reaches as high a collatz result as 250504.

willmarquis 363 days ago |

Interesting take. The visualization of the inverse tree highlights just how sparse the “preimage space” is under Collatz iterations. The idea that this sparsity contributes to the apparent randomness is compelling. I’m curious whether modeling the process modulo powers of 2 and 3, or via 2-adic analysis, could formalize some of these heuristic observations. Also, the assumption that most numbers “fall off” rapidly aligns with empirical behavior, but it’s still not clear how to bound exceptional trajectories.

90s_dev 363 days ago |

> I've been telling people for years if businesses want employees to have better ideas, they should have more showers in their offices. So far everyone seems to think I'm joking. I'm not.

I have definitely noticed that some of my best ideas or breakthroughs come to me when showering, or sleeping, or eating, or driving, or doing the dishes, or basically any mundane autopilot task where my mind is free to wander. But yeah no, having a shower room in the office is both gross and weird. Maybe offices should.. encourage you to... wash some dishes?

gpm 363 days ago | |

I've worked in an office with a very nice (clean, private, towels and soap dispensers provided) shower. Actually two (in separate rooms). And taken showers in them. It definitely was not gross, nor do I think anyone thought it weird, nor was I the only person who used them.

After a bicycle commute to work though, not randomly during the day.

xigency 363 days ago | | |

Taking a wild guess, was this at Fog Creek / Stack Overflow?

90s_dev 363 days ago | | |

Depends. In skyscrapers with multifloor offices, sure. Regular small-ish offices, the showers would be too proximal for comfort.

amszmidt 363 days ago | |

Sinks where you wash dishes tend to be far more dirty than any shower.

Having showers at work is awesome, it means you can take a proper bike ride to work, and freshen up.

coolcase 363 days ago | |

Most places I work have a shower - albeit not just off the main office. Usually part of the building infra. It's great if you cycle to work for example or play sport at lunchtime. It's a good thing if well placed.

dotancohen 363 days ago | | |

What's the trick to finding it?

snarf21 363 days ago | |

I think that the shower just slows your brain down just enough to get into flow. I've found that walking and driving do the same for me as well.

spocchio 363 days ago |

Awesome! Now, what about plotting in 3D? with the coordinates of (f_n, f_{n+1}, f_{n+2}) ?