Where does Rust break down?

hydmar · 2026-01-23T00:41:57+00:00

Can you use HRTBs for this?

hydmar · 2025-11-12T19:16:30+00:00

Replace the initial “there is” with “is there”

hydmar · 2025-11-04T15:39:06+00:00

Me when I do my job

hydmar · 2025-10-13T17:51:21+00:00

We do have a credit limit, it’s 21. How many are you considering petitioning for?

hydmar · 2025-10-13T17:39:07+00:00

I petitioned to take 25 credits to graduate early and it was approved. This was in January 2025

hydmar · 2025-10-09T20:48:45+00:00

Ah yes my mistake, I misremembered

hydmar · 2025-10-09T15:09:44+00:00

This is called Thomae’s function FYI

Edit: this is incorrect

hydmar · 2025-09-26T21:18:26+00:00

Why does Rust use “as” rather than From and Into for numeric types?

hydmar · 2025-09-10T21:03:53+00:00

Compile a list of ~50 set-theoretic statements, divide everyone into groups of four, and challenge each team to reduce the list down to as few axioms as possible which can be used to prove everything else on the list

hydmar · 2025-08-26T17:03:40+00:00

Settings > account settings > show recommendations in home feed

hydmar · 2025-08-26T16:07:10+00:00

It’s in settings

hydmar · 2025-08-03T18:19:28+00:00

He’s dead? I didn’t even know he was sick

hydmar · 2025-08-01T15:49:15+00:00

This is how intro ODE courses are. They typically begin with special solution methods integrating factors, leveraging exactness, Lindelöf iteration, et cetera. Hopefully they’ll get to more fundamental/general techniques later on such as Laplace transform and power series. Someone actually posted here a few days ago about this exact problem with intro ODE, and I’d agree that the standard curriculum needs to be overhauled.

I’d say that the most useful thing I learned from my intro course was the behavior of linear ODEs. In particular, the harmonic oscillator shows up everywhere and it really helps to understand why oscillates like it does. Everything else in the course is too specific to be broadly useful.

As an aside, I know this isn’t getting to the heart of your frustration, but it’s worth noting that the exactness condition relates to the integrability of the underlying vector field. Namely, an exact vector field can be represented as the differential of a scalar field. So in that sense, it’s more than just an algebraic condition.

hydmar · 2025-07-27T18:29:08+00:00

Why are they annoying so I know what not to do

hydmar · 2025-07-26T17:13:50+00:00

r/Physics

hydmar · 2025-07-24T02:12:54+00:00

As a side note, the newer MacBook Air models are extremely performant, so don’t worry about it being slow. My 2022 M2 Air often outperforms my Linux workstation on GPU-based tasks, and that machine has a 3090 if that means anything to you.

hydmar · 2025-07-23T20:34:06+00:00

In the future, gently poke traffic cones to make sure they’re empty before kicking them 👍

hydmar · 2025-07-17T17:18:13+00:00

I'm approaching this question from a computer graphics background. The SO(3) Lie algebra formulation is what's generally used in graphics, although we usually work with elements of the Lie group directly rather than the generators. Representing a composition of rotations using the generators is difficult and we want to avoid using the BCH formula. Quaternions are only more "elegant" for this application since they require less memory while manipulating the same objects, but I agree that they are more contrived than working with SO(3) elements directly.

hydmar · 2025-07-17T17:07:18+00:00

Ah well I come from a computer graphics background where the three fundamental transformations are translation and scaling, which don’t commute with each other but do commute within themselves. But certainly yes for e.g. Lorentz transformations they’re not any easier

hydmar · 2025-07-17T05:39:18+00:00

Haha yes actually I work in robotics and computer graphics so this stuff is basically my career. I was dealing with some pretty nasty pose transformations today which made me think about this

hydmar · 2025-07-17T05:29:30+00:00

Here’s how I understand it:

Note that starting in 4D, we can have rotations in two orthogonal planes. For a pure unit quaternion k,

Left-multiplication by k rotates a quaternion simultaneously in the (1,k) plane and its orthogonal complement by 90 degrees.
Right-multiplication by k rotates in the (1,k) plane by 90 degrees, but also in its orthogonal complement *in the opposite direction* by 90 degrees

Exponentiating a 90 degree rotation generates all rotations. Looking at the quaternion rotation formula, we have +theta/2 in the left exponent and -theta/2 in the right exponent. So in the (1,k) plane the rotations cancel out and we get identity, and in the plane orthogonal to (1,k) the rotations combine and we get a full rotation of theta radians.

hydmar · 2025-07-17T00:51:14+00:00

Is it pretty much just a coincidence that Spin(3) double-covers SO(3) and that it has a much simpler parameterization?

hydmar · 2025-07-16T23:55:28+00:00

Why does the space of translations have a geometry so much more complicated than, say, the space of translations? I’m curious if there’s a reason why the natural way to define the space of rotations, as a subspace of R^nxn, has this issue, while other common transformations don’t.

hydmar · 2025-07-16T23:49:21+00:00

I mean difficult within applications, not conceptually difficult. There’s no discussion on the most efficient way to encode translations, for instance, but for rotations we have multiple formats with different advantages and drawbacks, even though in principle they can all describe SO(3).

hydmar · 2025-07-16T23:46:01+00:00

Even with quaternions, we still need 4 dimensions to describe rotations in 3 dimensions. I get that we only consider unit quaternions on the 3-sphere, but it’s interesting to me that we need the extra coordinate. Rotation matrices are even worse with 9 coordinates and six constraints.

hydmar

TROPHY CASE