HN user
Unrepentant ultracrepidarian
http://www.fabian-lischka.de
hackernews@fabian-lischka.de
[ my public key: https://keybase.io/fab; my proof: https://keybase.io/fab/sigs/XVCHiJ8si5GOpHUKjHh8QVkG9Czgvft0ZTZGHmRLnkI ]
Ceterum censeo Elsevier(um) esse delendum.
BTW, counterexamples in mathematics are really important and often help to refine definitions and sharpen proofs.
1) I recommend the wonderful 1976 book Proofs and Refutations by Imre Lakatos.
2) There is a considerable list of books dedicated to counterexamples, e.g. in topology, probability, analysis, etc.
Suggest Prowlarr instead of jackett.
BTW, there was a variant of this discussion with the iPod and mp3 players back then. Some people wanted to manage music "by hand" in the file system, and had various schemes for doing so (folders for genre, then artists, then album, etc.), and wanted that reflected 1-to-1 in the mp3 player.
iTunes (and the iPod) had a different idea: The app takes care of file management, and you have a frontend supported by a database containing all sorts of metadata to browse your music (both static metadata (artist, genre) and dynamic (play count, skip count, last heard)). iTunes has smart playlists which I love (all songs with 3 stars or more that I haven't heard in 6 weeks).
I'm firmly in the latter camp, and similarly prefer Jellyfin over a pure SMB share for movies.
Übergegenbeispielt.
Indeed. Particularly when traveling, I often look for just several bytes of information (an address, when the ferry leaves, etc.), yet the websites contain several megabytes. Frustrating & slow.
Yes, the bash.org IRC archive archive is hilarious:
https://web.archive.org/web/20230620135556/http://bash.org/?...
Assume the book is the same form and size as the hand (though very thin).
My intuitive take:
Eigenvectors answer the question, if you have a linear mapping from a space to itself: which lines through (through the origin) remain unchanged after the mapping? And the associated eigenvalues tell you how much a specific point on that line moves along the line. For example: If you rotate things in 3D, the rotation axis remains unchanged. That's the eigenvector. If you reflect things through a mirror plane, any line in that mirror plane will remain unchanged (with eigenvalue 1). Other lines will be, well, mirrored, but there is one line that is reflected onto itself: the one perpendicular to the mirror plane. However, points on it will go from one side to the other, so have eigenvalue -1.
The SVD says something else: Any linear mapping from a space (to itself or a different one - higher or lower dimensional) can be expressed as 1) first a rotation in the old space, then 2) some coordinate scaling or dilation (expansion/contraction) along the coordinate axes, described by the diagonal matrix with singular values, 3) then another rotation in the new space.
Just to add: Credit is also due to Prof Christian Reinsch from Technical University of Munich (in addition to Golub and Kahan) for the invention of the practical algorithm for computing the SVD still in use today.
https://blogs.mathworks.com/cleve/2022/10/23/christian-reins...
https://people.inf.ethz.ch/gander/talks/Vortrag2022.pdf
https://www.mathworks.com/company/technical-articles/profess...
BTW, if you wonder about the dedication ("For Gene Golub on his 15th birthday"):
Gene Golub was a numerical analyst, and father of the practical singular value decomposition (his license plate read "Prof SVD"), together with William Kahan (the father of IEEE 754 floating point numbers).
And his birthday was February 29. (In other words, the article was on the occasion of Gene's 60th birthday).
https://en.wikipedia.org/wiki/Gene_H._Golub
RIP.
Indeed. I like to say, we would like three things to be true:
1) Every day has 86400 seconds.
2) Every day is from noon (sun exactly above) to noon (sun exactly above).
3) We use SI seconds.
You can't have all three. Pick any two:
1, 2, not 3: What you describe. Day has 86400 seconds, we keep in sync with the sun, but we tweak the seconds a bit. There are different versions, like epoch time, or UT1.
1, not 2, 3: Every day has 86400 SI seconds, and we slowly go out of sync with the sun. That's TAI.
not 1, 2, 3: We use SI seconds and keep in sync with the sun +/- 1 second, but need to add/drop seconds occasionally. That's UTC.
https://en.wikipedia.org/wiki/Universal_Time
As my Linear Algebra prof used to say, basically everything is applied Linear Algebra.
Not really. It's still the standard deviation, and it still gives you bounds on probability, for example the Chebyshev inequality:
P(|X-\mu| > k \sigma) < 1/k^2.
So, while for a normal RV, 5% of observations lie outside +/- 1.96 std.devs, for arbitrary RV (with finite variance) at most 25% of observations lie outside +/- 2 std.devs.
That's disappointing, both that the vulnerability exists in the first place, and that Apple takes over a year to not even fix it.
Even with equities, things are not entirely trivial.
A few examples: Some stocks trade in one currency, but pay dividends in a different currency. Some stocks go ex-div before the dividend amount has been determined (e.g. in Japan). Stocks trade on certain days, and trades settle on certain days, and they might be subject to different holiday calendars. Corporate actions are not entirely trivial, either (with rights issues, you need to issue two temporary securities for accounting purposes, etc.).
TFA, in Appendix A: Resources, lists many.
Well, that's not money created out of nowhere. The balance sheet extension creates money and an equivalent liability. That's the point of the statement, not money supply and its regulation.
How is the client going to pay that? They can't be charged half a cent.
If someone sells you 12345.55 EUR vs USD at a rate of 1.12345, how many EUR do you think you end up with?
1. If someone sells me 12345.55 EUR, I hope to end up with 12345.55 EUR.
2. That's the point though. They will sell you a certain amount of EUR at a certain dollar price. This, in turn, implies a rate (which might well have more than 5 digits behind the decimal). This is ideally close to the quoted rate, sure. But what counts is the actual EUR amount and the actual USD amount, not what rate was quoted or with how many digits.
But it's a good idea to keep those values distinct from actual money. You can't pay a fraction of a cent to anyone.
What are those pretty trivial ways? And how are they better than storing 10 cents + 20 cents = 30 cents?
you're interested in the risk metrics, like durations, convexity, vega, and so on, no one cares what your rounding convention is. doubles are just fine, thank you.
Doubles are not just fine, but required there. If you compute risk, as you allude to, by finite differences, then you need the precision of floats rather than rounding to integer cents prematurely.
it borders on bad advice (e.g. "Balance is never stored. It’s derived from the movements of money.")
Don't think that's bad advice, in particular as the article clarifies:
Derived state can be cached. Balances and projections can be cached or snapshotted for performance.
Of course you can cache or snapshot. But don't mistake that with storing the golden source.
There's a fairly obscure T-shirt designed by FT Alphaville that just cryptically says "Allen, Ben, Janet, Jay" ;-)
Sorry, that strikes me as the norm. Graduation is predicated on passing certain courses, and obviously you can't take it an arbitrary number of times. So fail an exam twice, and you're out. (Some universities offer a final oral exam after failing a written exam twice.)
Indeed. Early to mid 1990's, that's where it was at. FTP, telnet, gopher were awesome, and then, in short order: HTML, Mosaic, Netscape - the WWW. Really useful.
Then AOL etc. offered cheap dial-up, and suddenly you had all those noobs online ("Eternal September"). Been going downhill since then ;-)
That might be an instance of Berkson‘s paradox.
You’ll hear about deadly small plane accidents, and about accidents of large planes, but are unlikely to hear about harmless accidents with small planes. Just not interesting. But they happen all the time.
Note that here „commercial“ is commercial general aviation (so, not military and not scheduled airliners). Airliners are far safer still.
Similar in aviation, where it’s known as „the killing zone“.
But I can also teach a game designer or artist who has never heard of source control how to correctly and safely use P4 in about 15 minutes. Meanwhile you can tell Git is badly designed because there are 10,000+ tutorials explaining how easy it is! Spoiler: things that are actually easy do not need 10,000 tutorials telling you that it is easy.
100% and LOL. Sometimes I wonder where we'd be if Mercurial (hg) had won that contest.