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@codepuppy the matrix form is the same physical calculations as trigonometry basically.

@codepuppy oh no, nothing to do with concurrency. its about the axis getting aligned through rotation and thus loosing a degree of freedom and thus can not achieve certain combinations of rotations with vectors unless you add in an extra computation to check for an correct for gimbal lock.

@codepuppy yes thats pretty much the jist of it. though it doesnt have to be matrix math itslef. we are really talking any arbitrary computer instruction executed across a large set of data simultaneous. No reason matrix math needs to be part of that discussion other than the fact that vectors are analogous with matrix math.

@codepuppy mostly yes.. keep in mind on a GPU when it parallelizes a problem it isnt like a CPU, it has what is called a SIMD architecture, this stands for "Single Instruction, Multiple data". It basically means for it to be efficient at using all its cores (which tends to be hundreds) at solving a problem the instruction set must be singular (and before you think of cheating, no it cant have a bunch of if-then branches either) but the data it operates on can be many and varied.

Rotations fit this description, you have a ton of points but the instructions on how to rotate them are all the same. so you can trivially parallelize it.

What I am saying though is not that the quaternions are better for this what i am saying is the computational effiency of quaternions over vector math is **negated** by this... using vector match to rotate 100,000 points would be much slower than quaternions if we were using a single CPU to sequentially do each one, so quaternions would be the clear choice. However when we are able to do the rotations on a GPU and parallelize it across hundreds or even thousands of SIMD cores then the vector math while computationally inefficient on a rotation-by-rotation basis is so easily parallelized that the computational advantage of a quaternion isnt really needed anymore.

The gimbal lock advantage of quaternions however is valid regardless of any of this.

@pganssle handrolling a solution is trivial so thats not a problem, and ultimately that is exactly what I did.

The issue isnt that i wanted a pre-made class that had this behavior. Its that a true atomic counter can not be implemented by hand. Sure the implementation you linked behaves the same, but at a low level its using a lock. True atomic counters behave this way without engaging an actual lock and thus are much faster under certain scenarios.

@codepuppy there are only a few equations to rotate a single point yes, but you are rarely rotating a single point are you? Typically a rotation is of some shape in 3D space, that is represented of tens or hundreds of thousands of points that makeup the surface of that shape all of which are rotated by the same set of formula.

I have recently uncovered a user who seems to be opening temporary accounts at QOTO, blocking all the moderators so we dont see their posts and then posting high offensive material (nazi imagery, transphobic and hateful derogatory content, etc) and then proceeding to announce to block list moderators and possibly on the list in general in an attempt to get us banned.

The issue of users being able to block moderators and do **exactly** this is something I have brought up to @Gargron before probably over a year ago but he has never acted on fixing this issue and does not see it as needing fixing from what I could gather (he can interject here if he would like).

It is something we as moderators are powerless to detect or act against unless someone actually reports the content first, that is the only way we will even see it. Thankfully none of the block lists have actually acted on this and no damage to QOTO has been done. But seeing as this may continue I want to make others aware of the problem, press gargron to fix the issue once more, and also encourage **anyone** who sees such content on QOTO to please report it so we can act on it.

I can not personally confirm this but according to the block-list operator they seem to have reason to think it is @snow behind the attacks. This would be in line with the behaviors from snow I have witnessed in the past.

For the attempt by snow to spam and falsely accuse instances see here:

likeable.space/notice/A21ux0Ib

For more information see these attempted block requests on QOTO that were made in this fashion:

schlomp.space/FediBlock/data/p

schlomp.space/FediBlock/data/p

@arteteco @Sphinx @khird

@codepuppy Two reasons..

1) they are computationally more efficient for 4D rotations than their equivalent matrix/vector representation

2) this one is actually more important since #1 can be corrected for with parallelization... They are not susceptible to gimbal lock when calculating rotations.

@snow Please stop trying to play the victim... everyone you dont like or who disagrees with you you force your views on and have went so far as to open tons of alt accounts posting fake shit on instances you dont like hoping to get them blocked (and mostly failing)... You **are** the problem, look in the mirror, you are a horrible human being and what you do is far far worse than some drawings someone happens to do, you try to hurt actual people.

@codepuppy Your actually getting super close to realizing why their so powerful by realizing they arent using unit vectors... do yo uwant the answer?

@codepuppy They are just complex numbers more or less, really nothing too complex...

The magic that you seem to be missing though is still why they are useful, special and prefered for certain situations.

@codepuppy they are just complex numbers taken out to 4D instead of 2D, you can extend this to even higher dimensions with things like octonians and sedenions. Each level looses something though for example quaternions loose commutativity. but otherwise they arent that obscure when you think about it.

@codepuppy Way to go, its great to learn a new thing...

Here is the catch to really understanding Quaternions and how to use them though... do you understand what a quaternion can accomplish and why one might use it over the simpler to understand and more generally useful vector math? Afterall if you use vectors you can work in any number of dimensions whereas quaternions are limited 3D rotations or 4D points. So understanding why quaternions are superior for specific situations is really the key to getting them and using them.

AHHHHHH I finally understand quaternions!! XDD :DD

I always thought they were neat fun thing in abstract algebra and a neat but arbitrary way of representing rotations with unnecessarily extra numbers.

If someone had just said to me this sentence I would have seen how insanely perfect they are!! :D

As rotations, the i/j/k coefficients are the x/y/z components of the axis-of-rotation vector, and the fourth lone number is the amount of the rotation in radians!

#Math #Geometry #Quaternions

@kline I call it SpaceHeaterApp, it turns your computer into a space heater, doesnt even cost any additional hardware!

No in all seriousness its an implementation of my algorithm I invented for algorithmic trading.

The app is now officially 100% multithreaded with very little thread contention.. Man that wall of 100% CPUs (32 of them) is a beautiful sight.

🎓 Dr. Freemo :jpf: 🇳🇱  
So my app is running only across 32 cores so only 32 threads in action (well its python so multiprocessing)... yet it has 3,201 lock objects total ...

@GodfreyHendrix Algorithmic trading, specifically an algorithm i developed that is applied to that purpose. It works in real time and sequentially, so not something most people would think could be parallelized, and for real-time it didnt need to be. But was far too slow for backtesting so parallelization was needed to backtest.

@Zest

Yup relativity as a whole is definately pretty much experimentally proven at this point even if not all of its individual components have direct evidence.

@Science

@Zest

The riddle/paradox can be found here:

en.wikipedia.org/wiki/Ladder_p

> but either way what I'm curious about is why saying that the things literally happen at different times relative to different places makes more sense than just saying "well the light took this long to get here so we're just seeing it now".

The reason is because its the only way the other things make sense without there being a paradox... If time **actually** dilates (and we have experimental evidence that proves that, it was proven on GPS systems for example) that means the actual time expiernced by different frames of reference must be actually different. If the time is actually and literally different then clearly the events must also occur at different times.

Because all 4 concepts, time dilation, velocity dilation, length constriction, and simultaneity are all interdependent on each other then either they are all an illusion , or they are all real, if you mix and match it you get logical paradoxes that make no sense. we can and have proven that time dilation is real as well as velocity dilation, as we can prove it in particle accelerators, so we know that the others must be real as well.

We have also seen length contraction inside colliders (in this experiment it was observed that gold ions were contracted to a thin disc like shape: physicsforums.com/threads/mode )

However directly and experimentally confirming the ladder paradox itself, thats much harder and I know of no direct evidence of that. But as i said with the other elements being well proven it is the only logically consistent conclusion and matches the math.

@Science

So my app is running only across 32 cores so only 32 threads in action (well its python so multiprocessing)... yet it has 3,201 lock objects total instantiated to accomplish that with minimal read/write contention....

I can honestly say this is the greatest number of thread locks instantiated at a single time that I have ever needed in an application before.

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