markstock

7 ms·

1.
by markstock 15d ago
But IFS and L-systems don't help explain the phenomena (the "how"), just its expression. Fractals are not a building block, physical forces are. Where one or more physical forces are dominant over a range of spatial or tempor
2.
by markstock 16d ago
This seems very related to adaptive meshing algorithms, for which there are many naive formulations, and not all are intractable.
3.
by markstock 27d ago
Yes, the simpler versions were discovered earlier. The point that my brain wanted to make was that the article, like so many others in science communications, omits parts of the story that would make present discoveries seem less groundbrea
4.
by markstock 29d ago
It's a little weird to talk about the origins and our understanding of the Euler and Navier-Stokes equations and not mention that they are both truncations of the Boltzmann equation from gaskinetics.
5.
by markstock 1mo ago
You just reminded me of a great feature that I think I first noticed in The Gimp: you don't have to search through the list of file types when exporting (I almost typed "saving"!), just type the extension in the file name and
6.
by markstock 1mo ago
It's when I want to close the image or the application - the extra click to confirm that, yes, I am aware this image was not "saved" and that I could be losing data. I admit I have not looked into whether I can disable that e
7.
by markstock 1mo ago
Now that it's not late at night I can see a mistake: the primary benefit of regularization in nbody methods (self-influence being zero and not infinity) is stabilization of the dynamics. A close pass will not send one or both particles
8.
by markstock 1mo ago
And Gimp users are not more likely to know that? It adds up to extra clicks for 90% of the images I load.
9.
by markstock 1mo ago
The tweaks that SW included are pretty common to similar simulations: 1) the attraction-repulsion pair is typical of "boids" simulations, and also features in the Lennard-Jones forces acting in atoms (albeit with different powers
10.
by markstock 1mo ago
A friend of mine has made some artwork about the AMOC, notably: https://www.benbray.com/apmoc.php Another set of works (a video simulation and a physical installation) show the slow turnover of warm and cold water: https:&
11.
by markstock 2mo ago
The nice thing is that every gpu is like a little distributed-memory machine, and programming it for optimal memory locality (registers, shared, global) and bandwidth is an essential skill. One step up is using multi-node distributed memory
12.
by markstock 2mo ago
The author is spot on. As an HPC performance engineer and computational artist, I could tell numerous stories about it, but I'll summarize three: The common method for evaluating MPI performance on a supercomputer is with the OSU micro
13.
by markstock 2mo ago
Please don't call this "full N-body dynamics" if only the outer planets are involved in the integration.
14.
by markstock 2mo ago
My go-to rule that's held since 2008 has been that a GPU can do about 10x the math that a similarly-priced CPU running properly optimized code can. My 5070Ti can realize about 20 TF/s while a 12-core Zen5 can do 2.
15.
by markstock 2mo ago
There have been polls. The AI hate thing is almost exclusively a USA thing.
16.
by markstock 3mo ago
Generative artist here: the beautiful thing about this exploration is that these techniques can be applied to ANY vector field, whether they originate in random noise or global simulations. The reason these add so much visual interest to a
17.
by markstock 3mo ago
Yes, I do 4th order interpolation (M4') on the GPU. This paper is for 3rd order, though, but the methods may extend. I suppose because the fetches are generally to similar memory regions, there may not be a substantial performance impr
18.
by markstock 3mo ago
I should add that this is a major "tell" for detecting when an app uses the Stable Fluids method: obvious mass loss (and very viscous, energy-dissipating flow).
19.
by markstock 3mo ago
People who run WSL are not normal users. The filesystem problems make Windows+WSL feel like a Trabant when you're used to a Porsche.
20.
by markstock 3mo ago
Because Windows is the operating system of Not Getting Fired. Fear is a stronger motivator than creativity or productivity.
21.
by markstock 3mo ago
On the other side, I am a lifelong Linux user, and even with advanced LLMs, trying to get Microsoft Windows to behave sanely takes hours every month for years on end (thanks, day job). Things Linux figured out in 2003 are still magic or com
22.
by markstock 4mo ago
Before you go adding vorticity confinement, consider performing a higher-order backward advection scheme (Runge-Kutta 2nd or similar), and using a higher-order interpolation method (triangle-shaped cloud instead of bilinear). In my implemen
23.
by markstock 4mo ago
You are correct: Stable Fluids extends to 3d relatively easily.
24.
by markstock 4mo ago
One of the nice aspects of Stable Fluids is that you don't need to iterate the pressure correction terms to convergence. Just run a fixed number of Jacobi or Gauss-Seidel sweeps and keep performance consistent. The only drawback of thi
25.
by markstock 6mo ago
Then you want Foundations of Multidimensional and Metric Data Structures by Samet. Unless you already have it, then enjoy some pretty (organic) trees.
26.
by markstock 9mo ago
Sure, I usually measure performance of methods like these in terms of FLOP/s; getting 50-65% of theoretical peak FLOP/s for any given CPU or GPU hardware is close to ideal.
27.
by markstock 9mo ago
Quadtrees and octrees are themselves quite deep research areas. If the acceleration data structures interest you, I highly recommend Hanan Samet's book "Foundations of Multidimensional and Metric Data Structures". It's f
28.
by markstock 9mo ago
Note that even without an acceleration structure ("direct summation" in N-body research terminology), a CUDA program or GLSL shader program can exceed 60 fps with 10,000 to 20,000 particles. And a parallel, C/C++/fortran
29.
by markstock 9mo ago
The general algorithm used here (of computing attraction and repulsion forces between pairs of particles) is very similar to that used in simulations of many interesting phenomena in physics. Start with Smoothed Particle Hydrodynamics ( htt
30.
by markstock 9mo ago
Thank you - I was just about to point out some of that. The reason that the flocks are tight is because the separation "force" is normally computed as a repulsion between a target boid and all other nearby boids individually, not

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