The halting problem is easy actually. The program will terminate when the computer breaks. Duh.

Two black cats sitting in the windowsill looking at the camera

My twin Lovecraftian horrors are back for #caturday #catsofbluesky #cat

Thanks for the tip!

They look so sweet. I hope they find a forever home soon.

500 days— that’s how long Ash & Willow have been waiting for the right family. Can you help us find them? Learn more at crits4cats.petfinder.com
(The .org in the thread doesn’t work properly).

A black cat in a person's lap, looking at the camera with his widdle red tongue poking out

A very good blep. #cat #catsofbluesky

A black cat sitting in a white sink looking up at the camera

We love sink #cat

Likewise!

A panel from the manga "Destroy all Humans they can't be regenerated." It shows 3 people around a gaming table, looking overjoyed. Speech bubbles say "Ooh sounds great! I love drafts most of all."

Me too guys. Me too.

Source is "destroy all humans, they can't be regenerated" volume 2.

They're good cats though. And that's what matters! (They're all good cats.)

A black cat relaxing on a grey doughnut shaped bed looking at the camera. His name is Nyarlathotep.

Slowly coming to terms with the fact that I'm not a science account that posts cats. I'm a #cat account that sometimes posts about science.

A grey cat lying on her side, looking up at the camera, with her paws in front of her

For this #caturday I present Emmy's beans. #cat #catsofbluesky

Minecraft redstone

This absolutely made my day

Thank you! And I've heard that.

Thank you! Excited. Ann Arbor seems like a great place.

Not for long ;)

Thank you, Thomas! I'll be one of several LANL scientists moving to Michigan to help make this happen. I hope we can make it a success and do good things. Very excited about the science I'll be working on and the people I'll be working with.

Two black cats arranged as mirror images of each other on a bookshelf

Nyarlie and Yoggie ready for #caturday #cat #catsofbluesky

A black cat sitting in a bookshelf looking at the camera

Nyarlie is both a gentleman and a scholar. #cat #catsofbluesky

It's not every day that you get to touch programming and video game lore in a science project. But today was such a day. Thanks to my colleagues Jacob Fields, Peter Hammond, and @astrobarker.bsky.social for helping make this happen.

End 🧵

GitHub - lanl/not-quite-transcendental: Reference Implementations of Not-Quite-Transcendental Functions Reference Implementations of Not-Quite-Transcendental Functions - lanl/not-quite-transcendental

And if you're interested in playing with it yourself... You can! He's the source code
github.com/lanl/not-qui...

👇

Stimulations of a neutron star where the equation of state is tabulated with both logs (left) and NQT (right)

And we show our NQT functions in action in simulations of a neutron star.👇

Plot of speedups up NQT functions vs their transcendental counterparts for a variety of architectures

We show the method is faster than normal logs for a wide variety of architectures including CPU and GPU, with negligible cost in accuracy (for linear interpolation).👇

Quake 3 arena menu screen. Credit Id Software

And it turns out, not entirely by coincidence, that the simplest of these is in fact the first part of the infamous quake 3 inverse square root algorithm. This is the "evil bit level hacking" in the method. (Image credit Id Software) 👇

It turns out there's a whole family of functions, much cheaper to evaluate than logarithms, that can be constructed by taking advantage of the structure of floating point numbers. We call these functions Not Quite Transcendental (NQT for short).👇

What's actually important about logarithmic interpolation is that logs are invertible and that a variable that is evenly spaced in log space really has a spacing proportional to its magnitude. That is, the grid spacing is larger the larger the physical values are. 👇

Not-Quite-Transcendental Functions For Logarithmic Interpolation of Tabulated Data From tabulated nuclear and degenerate equations of state to photon and neutrino opacities, to nuclear reaction rates: tabulated data is ubiquitous in computational astrophysics. The dynamic range that...

Paper day! This is a fun one if you like low level #hpc #programming hacks. 🧪🔭

In computational physics ⚛️, we often interpolate tabulated data that spans many orders of magnitude. A common way to do this is to tabulate in log space. But logs are slow... Or are they? 🧵👇

arxiv.org/abs/2501.05410

I like that!

Also, if you learn how to debug bureaucracies, please let me know! God knows I could use the help.

When trying to understand what's happening, there's absolutely no substitute for instrumentation!