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fxjon Cracovians: The Twisted Twins of Matrices

I didnt get the explanation of the multiplication. After reading the wikipedia article it made mode sense:

https://en.wikipedia.org/wiki/Cracovian

The Cracovian product of two matrices, say A and B, is defined by

A ∧ B = BT A,

where BT and A are assumed compatible for the common (Cayley) type of matrix multiplication and BT is the transpose of B.

Since (AB)T = BT AT, the products (A ∧ B) ∧ C and A ∧ (B ∧ C) will generally be different; thus, Cracovian multiplication is non-associative.

A good reference how to use them and why they are useful is here (pdf):

https://archive.computerhistory.org/resources/access/text/20...

fxjon Munich from a Hamburger's perspective

Damn, he mentioned Andy's Krabblergarten. Now it will be overrun with even more tourists. My serious advice: Don't go there!! The Schnitzels are aweful and the Beergarden is ugly. ;-)

Too bad that Google, Apple, Intel now have offices here. This drives the rents up. Gentrification already killed the gay quarter. All luxury appartments and people now start complaining that the vibes of the quarter are gone. Who would have thought...

fxjon Munich from a Hamburger's perspective

Hamburg is more conservative than Munich (I have lived in both cities). It is more like Austin wehen you compare it to a city in Texas. And Hamburg is in no way as hippy as San Francisco was. The closest I would compare Hamburg to is Boston.

In the golden 70s Munich was a melting pot for musicians, gay people, Hippies. They still have the nudist beach in the city centre. Try to find something like that in the US.

fxjon Munich from a Hamburger's perspective

Hamburg has a harbor and is at the riverside of a large stream so that makes it a complete different setup. Munich on the other hand still has a castle in the inner city (Residenz) and has many historical buildings. Hamburg has the status of a "state" in Germany while Munich is the capital of Bavaria (a state in Germany). Both cities are rich and the rich people also celebrate the weath in both cities. If you want a party city you better go to Berlin. (Arm aber sexy (Poor but sexy)) is their slogan.

fxjon Munich from a Hamburger's perspective

Well I live very close to Theresienwiese and dont have any problems at all. During the 2 weeks of Octoberfest they clean the streets every morning at 4am and everything is clean and shiny again. Also now that the Theresienwiese have been encircled by a fence during Octoberfest the numbers of drunk people has fallen dramatically.

fxjon Munich from a Hamburger's perspective

Munich has a smaller version of the Octoberfest all year around. Beer Gardens everywhere, many people wearing "Tracht". The tourists love it and the munich people love the money. It has some nice places like the English Garden or the River Side. Also the Farmers Market in the city centre is nice to hang around. It is not for the young crowd but more for the settled and wealthy ones. Very much like Zürich, but bigger. The mountains are close and the lakes around Munich are famous. Also many nice castles like Schloss Nymphenburg, the Residenz and of course the castle built by Ludwig II. Lots of historic buildings. The city was founded 1158 and parts of the old city still exist.

fxjon Munich from a Hamburger's perspective

Münchner here. It is a very touristy city. Dirty? not so much in comparison to other german cities like Cologne or Berlin. Uninviting and boring depends what you want to do. Nightlife in comparison to Berlin is poor. All the techno clubs are there. Octoberfest is a melting pot for the whole world. Americans and Australiens have a hard time digesting the amounts of beer.

fxjon Munich from a Hamburger's perspective

You can see them on sunny days when the wind blows from the south. So called "Föhn" weather.

fxjon Carolina Eyck, renowned superstar of the theremin

There are still several companies who build it. Get one from Doepfer (German Manufacturer) here and connect it to a modular system or a semi-modular synth like a mini moog.

https://www.thomann.de/de/doepfer_a178.htm

https://doepfer.de/a178.htm

live in action: https://youtu.be/1mIferngPqY

or from stylophone:

https://www.thomann.de/de/duebreq_stylophone_theremin.htm

live in action: https://youtu.be/NNn-se0S4Ww

fxjon Advanced Python Features

This is all fun and games unless you have to debug someone elses code and they use a new feature that you didnt know about. Speaking for myself, I would be glad if there were a python_light version of the interpreter that has a simple syntax only like the early 3.x versions.

just my 2 ct

fxjon 100 Years to Solve an Integral (2020)

Yes the dirac comb for example. Actually there are infinitely many.

https://en.wikipedia.org/wiki/Dirac_comb

and for other:

http://www.systems.caltech.edu/dsp/ppv/papers/journal08post/...

fxjon Researcher proposes model replacing dark energy/matter to explain universe

Or it might be at such high energies, that conventional particle accelerators will never observe it. Sterile neutrinos, axions and quintessence particles might have masses in the PeV range. We were lucky with the Higgs, and the W and Z Bosons, and the top quark.

Dark matter and dark energy might be a phenomenon in the GUT regime, which we will not observe with particle accelerators. We need more information about the Higgs, because it sticks out like a sore thumb of all the other particles. It is our first glimpse into the underlying fabric of the universe, as the Higgs field is non-zero everywhere and a scalar field. No other (known) particle behaves like that. But a future collider is expensive...

just my 2 cents

good plot for a scifi movie: aliens measure a different vacuum value of the Higgs field and discover sub-space communications ;-)

fxjon Researcher proposes model replacing dark energy/matter to explain universe

Well, actually we have developed a very good feeling when to apply which theory. From subatomic particles to the large scale structure of the universe the right theories applied give us excellent results. lambda CDM models very well fit to the observed structures and the standard model describes all the particles that have been observed so far. We are desparately looking for effects that are unexplained by the standard model in particle physics so far. That is the reason why it is so difficult to justify yet another particle accelerator at CERN.

my 2 cent

fxjon Researcher proposes model replacing dark energy/matter to explain universe

The equations that we already have are sufficient to describe the universe to 99.9999999% but they are a hodge podge of several different theories that all work very very well in their respective regime. QM + GR + Lambda CMD + ...

But this just doesnt look nice to eye and the mind. The laws of nature "must" be shorter, more symmetric. Thats why we invented Superstrings which solves everything, but can never be tested...

my 2 ct

fxjon Researcher proposes model replacing dark energy/matter to explain universe

The neutrino was also a particle that nobody could observe at the time when Pauli proposed it. It was just a manifestation of the energy and spin conservation.

The Higgs is the same. It is not needed, but it solves the mass problem of the weak force. It is the only scalar field so far that we have observed and it was not clear whether it would exist at all.

Quintessence and sterile neutrinos are also just pieces that make the equations of the world look prettier, but they are also candidates for dark energy and dark matter.

Pauli wrote in his famous letter:

"I agree that my remedy could seem incredible because one should have seen those neutrons very earlier if they really exist. But only the one who dare can win and the difficult situation, due to the continuous structure of the beta spectrum, is lighted by a remark of my honoured predecessor, Mr Debye, who told me recently in Bruxelles: “Oh, It’s well better not to think to this at all, like new taxes”. From now on, every solution to the issue must be discussed. Thus, dear radioactive people, look and judge."

https://icecube.wisc.edu/neutrino-history/1931/01/1931-pauli...

fxjon QVQ-Max: Think with Evidence

https://ollama.com/joefamous/QVQ-72B-Preview

Experimental research model with enhanced visual reasoning capabilities.

Supports context length of 128k.

Currently, the model only supports single-round dialogues and image outputs. It does not support video inputs.

Should be capable of images up to 12 MP.

fxjon What's happening inside the NIH and NSF

30 days of vacation plus 24 days for overtime are very often found. especially in university/governmental jobs.

fxjon What happens if we remove 50 percent of Llama?

After reading the article it seems to me that this is more like synaptic pruning where weak connections between neurons are eliminated in order to increase the efficiency of the neurons. Interesting to see that this also works for LLMs.

https://en.wikipedia.org/wiki/Synaptic_pruning

fxjon QwQ: Alibaba's O1-like reasoning LLM

I am right now playing with it running it locally using ollama. It is a 19GB download and it runs nicely on a nvidia A100 GPU.

https://ollama.com/library/qwq

fxjon Raspberry Pi CM5 is a faster, drop-in upgrade

The Ableton Move is just a CM4 with linux (abletonos) running and using a SD-Card in the box.

https://www.reddit.com/r/ableton/comments/1fzd9ln/move_is_a_...

fxjon Raspberry Pi CM5 is a faster, drop-in upgrade

THe Raspi CM is also used in some synthesizers like the Korg Wavestate or the Ableton Move.

fxjon OpenMP 6.0

You can now (already in OpenMP5) use it to write GPU programs. Intels OneAPI uses OpenMP 5.5 to write programs for the Intel PonteVecchio GPUs which are on par to the Nvidia A100.

https://www.intel.com/content/www/us/en/docs/oneapi/optimiza...

gcc also provides support for NVidia and AMD GPUs

https://gcc.gnu.org/wiki/Offloading

Here is an example how you can use openmp for running a kernel on a nvidia A100:

https://people.montefiore.uliege.be/geuzaine/INFO0939/notes/...

  #include <stdlib.h>
  #include <stdio.h>
  #include <omp.h>

  void saxpy(int n, float a, float *x, float *y) {
  double elapsed = -1.0 \* omp_get_wtime();

  // We don't need to map the variable a as scalars are firstprivate by default
  #pragma omp target teams distribute parallel for map(to:x[0:n]) map(tofrom:y[0:n])
  for(int i = 0; i < n; i++) {
    y[i] = a * x[i] + y[i];
  }

  elapsed += omp_get_wtime();
  printf("saxpy done in %6.3lf seconds.\n", elapsed);
  }

  int main() {
  int n = 2000000;
  float *x = (float*) malloc(n*sizeof(float));
  float *y = (float*) malloc(n*sizeof(float));
  float alpha = 2.0;

  #pragma omp parallel for
  for (int i = 0; i < n; i++) {
     x[i] = 1;
     y[i] = i;
  }

  saxpy(n, alpha, x, y);

  free(x);
  free(y);

  return 0;
  }

fxjon Audio Decomposition – open-source seperation of music to constituent instruments

MPC3 - Yes

Mixcraft - Yes

Maschine3 - Yes

fxjon Audio Decomposition – open-source seperation of music to constituent instruments

If you are interested in audio (or stem) separation have a look at RipX

https://hitnmix.com/ripx-daw-pro/

It can even export the separated tracks as midi files. It still has some problems but works very well. Stem separation is now standard in the musical software and almost every DAW provides it.

fxjon Gravity is not a force

Does this mean that when the geodesic is a straight line then the particle stays on the geodesic, but when the geodesic is curved the particle interacts with its own e.m. field and deviates from the geodesic because it feels a deflecting force?

Then there would be a fundamental difference between curved and straight geodesics which would be a contradiction to the Einstein Equivalence Principle. How do physicists explain that contradiction?

fxjon Gravity is not a force

I found this paper which details how a charged particle falling into a black hole radiates. How is this possible when there is no acceleration on the particle?

https://adsabs.harvard.edu/full/1971PASP...83..633R

Title: Radiation from Particles Falling into Black-Holes

Authors: Ross, D. K.

Journal: Publications of the Astronomical Society of the Pacific, Vol. 83, No. 495, p.633

Bibliographic Code: 1971PASP...83..633R

fxjon Gravity is not a force

Question: Two black holes that encircle each other are on geodesic orbits and thus should not feel acceleration. However, graviational waves are emitted during the orbits until they merge. How is this possible when there is no accelleration acting on the masses?

fxjon Gravity is not a force

A charged particle on a straight line does not emit synchrotron radiation. What happens if it is on a geodesic? Do electrons that circle around a black hole emit synchrotron radiation?

fxjon Gravity is not a force

It is possible to unify the electromagnetic field into a geometric framework via the Kaluza-Klein theory which is just rewriting GR + ED. Then electromagnetic forces are also of geometric origin. How do you interpret this? Is electromagnetism then also not a force? I am not a physicist, so I am asking the experts.

https://en.wikipedia.org/wiki/Kaluza%E2%80%93Klein_theory

fxjon Gravity is not a force

Question to the physicists out there: When an electron gets accelerated it emits "Bremsstrahlung" because it radiates away photons when it changes its velocity vector.

So for an electron on a circular path in a magnetic field, we know that it emits this radiation because this is the synchrotron radiation.

Now what happens to an electron on a circular path around a black hole? Does it emit synchrotron radiation or not?