ColdQuanta Updated +Created
Not a quantum computing pure-play, they also do sensing.
Project Zomboid Updated +Created
Principal component analysis Updated +Created
Given a bunch of points in dimensions, PCA maps those points to a new dimensional space with .
is a hyperparameter, and are common choices when doing dataset exploration, as they can be easily visualized on a planar plot.
The mapping is done by projecting all points to a dimensional hyperplane. PCA is an algorithm for choosing this hyperplane and the coordinate system within this hyperplane.
The hyperplane choice is done as follows:
  • the hyperplane will have origin at the mean point
  • the first axis is picked along the direction of greatest variance, i.e. where points are the most spread out.
    Intuitively, if we pick an axis of small variation, that would be bad, because all the points are very close to one another on that axis, so it doesn't contain as much information that helps us differentiate the points.
  • then we pick a second axis, orthogonal to the first one, and on the direction of second largest variance
  • and so on until orthogonal axes are taken
www.sartorius.com/en/knowledge/science-snippets/what-is-principal-component-analysis-pca-and-how-it-is-used-507186 provides an OK-ish example with a concrete context. In there, each point is a country, and the input data is the consumption of different kinds of foods per year, e.g.:
  • flour
  • dry codfish
  • olive oil
  • sausage
so in this example, we would have input points in 4D.
The question is then: we want to be able to identify the country by what they eat.
Suppose that every country consumes the same amount of flour every year. Then, that number doesn't tell us much about which country each point represents (has the least variance), and the first PCA axes would basically never point anywhere near that direction.
Another cool thing is that PCA seems to automatically account for linear dependencies in the data, so it skips selecting highly correlated axes multiple times. For example, suppose that dry codfish and olive oil consumption are very high in Portugal and Spain, but very low in Germany and Poland. Therefore, the variation is very high in those two parameters, and contains a lot of information.
However, suppose that dry codfish consumption is also directly proportional to olive oil consumption. Because of this, it would be kind of wasteful if we selected:
  • dry codfish as the first axis
  • olive oil as the second axis
since the information about codfish already tells us the olive oil. PCA apparently recognizes this, and instead picks the first axis at a 45 degree angle to both dry codfish and olive oil, and then moves on to something else for the second axis.
We can see that much like the rest of machine learning, PCA can be seen as a form of compression.
Krusader Updated +Created
The most powerful GUI file manager ever?? Infinite configurability??
Ciro Santilli wasted some time on it before he gave up on file managers altogether.
Vector graphics Updated +Created
Smaller files, scalable image size, and editability. Why would you use anything else for programmatically generated images?!?!
enwiki-latest-categorylinks.sql Updated +Created
XPath Updated +Created
XPath kind of died with the rise of CSS selectors around the beginnning of the 2010's. But that is a shame. XPath is a good standard, and was generally more powerful than CSS selectors for many many years.
Box2D Updated +Created
f3d Updated +Created
Stimulated emission Updated +Created
Photon hits excited electron, makes that electron go down, and generates a new identical photon in the process, with the exact same:This is the basis of lasers.
Craig Steven Wright Updated +Created
This dude actually managed to convince a brain-dead British court that he was Satoshi and force a takedown of the Bitcoin whitepaper from bitcoin.org/bitcoin.pdf where it had been for many years prior: coinmarketcap.com/academy/article/bitcoin-org-ordered-to-take-down-bitcoin-whitepaper-because-of-copyright-infringement The page was updated to simply display the following Satoshi quote:
It takes advantage of the nature of information being easy to spread but hard to stifle. - Satoshi Nakamoto
Figure 1.
Craig Steven Wright
. Source.
The mere thought that Satoshi would attempt to copyright takedown the Bitcoin whitepaper, and not be able to back his identidy with any cryptographic keys, makes one shrivel to the bones.
Also, kids, this is why you put a fucking license on everything you release to the public, and especially when doing so anonymously!!! A quick CC BY-SA on that paper would have prevented all this bullshit.
The existence of this outrageous fraudster has had two good effects on the world however it must be said:
Timeline:
Interesting
Video game console Updated +Created
Who needs a hackable general purpose computer, when you can buy a completely locked down computer that only runs useless programs for which you have to pay thousands of dollars to develop for, cannot run a large percentage of major titles from competitor hardware due to business deals (see also) and will inevitably reach planned obsolescence in 4 years?
Punched card Updated +Created
Served as both input, output and storage system in the eary days!
Video 1.
1964 IBM 029 Keypunch Card Punching Demonstration by CuriousMarc (2014)
Source.
Video 2.
Using Punch Cards by Bubbles Whiting (2016)
Source. Interview at the The Centre for Computing History.
Video 3.
Once Upon A Punched Card by IBM (1964)
Source. Goes on and on a bit too long. But cool still.
Quantum compiler benchmark Updated +Created
These appear to be benchmarks that don't involve running anything concretely, just compiling and likely then counting gates:
bit gold Updated +Created
@cirosantilli/_file/numpy/numpy/fft.py Updated +Created
Output:
sin(t)
fft
real 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10
rfft
real 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 0 0 0 0 0 0 0

sin(t) + sin(4t)
fft
real 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 -10 0 0 0 0 0 0 0 0 0 0 0 10 0 0 10
rfft
real 0 0 0 0 0 0 0 0 0 0 0
imag 0 -10 0 0 -10 0 0 0 0 0 0
With our understanding of the discrete Fourier transform we see clearly that:
  • the signal is being decomposed into sinusoidal components
  • because we are doing the Discrete Fourier transform of a real signal, for the fft, so there is redundancy in the. We also understand that rfft simply cuts off and only keeps half of the coefficients

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