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Ask HN: Teach me something new

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421–430 of 782 posts

Re: Ask HN: Teach me something new

#421
post #50

Earlier quoted context omitted.

Yes, it was damn interesting. Thank you for sharing. Do you now try to read through all of your scotomas?

I will, but that incident was the last time I had a full-blown one.

Well that’s great to hear! May it be your last.

Re: Ask HN: Teach me something new

#422
post #254

I've described this on HN before; forgive me if you've already seen it. I have chronic migraine. It sounds worse than it is; I rarely suffer attacks anymore, and when I do, they're usually mostly harmless, as in the case I'll describe below. Contrary to popular belief, migraine is not a headache. It's something a little more like an epileptic seizure. Intense headaches are one common symptom, but there are a lot of o…

Generally speaking, scintillating scotomas don't fill the entire field of vision. They can do, and when they're caused by migraine auras they tend to grow and then shrink again within a 20-60 minute window. I can certainly read when I'm experiencing one. I can continue to work if I really want to, but I find that having a coffee and taking a break is much more comfortable. Migraine auras suck, but are pretty fascinat…

I didn't mention it, but I really like them. I mean, they're inconvenient, and they make me nervous because for most of my life they were followed by the horrible parts of a migraine, but the scotomas themselves are just so beautiful and interesting that I like them anyway. And in recent years I've been able to enjoy them without so much of the horrible parts afterward.

Re: Ask HN: Teach me something new

#423

I've described this on HN before; forgive me if you've already seen it. I have chronic migraine. It sounds worse than it is; I rarely suffer attacks anymore, and when I do, they're usually mostly harmless, as in the case I'll describe below. Contrary to popular belief, migraine is not a headache. It's something a little more like an epileptic seizure. Intense headaches are one common symptom, but there are a lot of o…

More than interesting. Thank you for sharing this experience. I’ve had mild scintillating scotoma a few times but didn’t know what they were, and never had any other symptoms of migraine.

I'd say your luck was good, in that you didn't have to experience the worst symptoms of migraine, but it was bad in that you didn't get to see some of the spectacular visions that I've been gifted with.

Re: Ask HN: Teach me something new

#424
post #421

Earlier quoted context omitted.

I will, but that incident was the last time I had a full-blown one.

Well that’s great to hear! May it be your last.

I'm sort of hoping I'll get another chance to try it. Obviously, I'd prefer another scotoma without the rest of the migraine, though!

Re: Ask HN: Teach me something new

#425

In a lot of terminals, Alt+. (or Option+. on Mac) will paste in the last argument of the previous command. $ mkdir hi $ cd You can hit . several times to cycle through earlier final args.

And if you don't want the last argument but the nth one, press Alt-n before Alt-. (n starts at 0, so Alt-0 Alt-. in the above situation would get you "mkdir").

There are several other ways to do this sort of thing too. See e.g. https://stackoverflow.com/questions/4009412/how-to-use-argum...

Re: Ask HN: Teach me something new

#426
post #344
post #232

Ordering a typical printed circuit board with components placed on it is so cheap nowadays that this is a viable option for electeonic hobbyists nowadays (e.g. just ordered 50 pieces of audio output amplifiers at 3,49 € per piece (customs and shipping included), where 1.60 € would be the parts cost of the two chips on it. Only thing you need for this is: 1. An idea and some knowledge about electronics 2. An EDA softw…

Out of all the hobbies I've had, electronics (mostly something to do with the ESP microcontrollers) is the most satisfying one once everything works as intended. While electronics knowledge is hard to learn on your own (in my case), there are tons of communities online that are more than willing to help.

What communities do you recommend?

Re: Ask HN: Teach me something new

#427
post #229

In statistics, the mean and median are both averages, but are technically quite different. The mean is the sum of all items divided by the number of them, while the median is the middle item in the sorted list. When they are different, this can have strange effects. For example, when estimating engineering tasks, the mean error is often positive while the median is often negative. This is why your manager believes th…

Interesting. I always learned mean/median/mode were different things. The mean is the average, the median is the middle value, and the mode is the largest value. I wasn’t aware of this issue with conflating mean/median.

That being said, I remember learning that and always wondering why I needed to know what “mode” was haha

Re: Ask HN: Teach me something new

#428
post #135

I've described this on HN before; forgive me if you've already seen it. I have chronic migraine. It sounds worse than it is; I rarely suffer attacks anymore, and when I do, they're usually mostly harmless, as in the case I'll describe below. Contrary to popular belief, migraine is not a headache. It's something a little more like an epileptic seizure. Intense headaches are one common symptom, but there are a lot of o…

Take some acid and what you are describing regarding consciousness becomes fairly apparent. The amount of things that automatically happen or get filled in for us goes unnoticed until you get a chance to step outside of it for a while.

I can't say that I agree. I got pretty thoroughly familiar with several psychedelics in the late 70s and early 80s, and although I value those experiences to this day, they didn't teach me anything especially relevant to the scotoma or sleep/wake experiences I've reported.

Re: Ask HN: Teach me something new

#429
post #260

You probably heard about the quirks in the French numerical system. For example, 99 is translated "quatre-vingt-dix-neuf" which is literally "four twenty ten nine". This is a legacy of the base 20 numerical system used by the Celtics thousands of years ago before the modern Romance language drove it out. The hybridization with our current base 10 system came with the Roman conquest of the Gaul. Another example of the…

The Danish language still has remains of this. 60 is 'tres', from three 20's. 80 is 'firs' from four 20's. The odd tens are even weirder, since they count upwards, so 50 is 'halftreds', which is half of the third 20; 70 is 'halffirs'; and 90 is 'halffems', four whole and a half of the fifth 20. But 100 is 'hundred', so 'fems' alone is never used. Also, for larger numbers, the digit order get weird: 123 is hundredogtreogtyve, one hundred and three and twenty.

Re: Ask HN: Teach me something new

#430

Earlier quoted context omitted.

Ever since I learned that the frequency ratio between adjacent keys on a piano is always a constant twelfth root of 2 regardless of whether you're going black-white or white-white, I've been sort of frustrated with the way pianos are designed. Transposing a song to a different key could have been effortless if keys were structured differently, such as with uniformly alternating white and black keys, rather than the 2…

Pianist here. I see where you're coming from, but I definitely do also rely on the different shapes of keys to know where I am without looking. I've been learning to play the button end of an accordion and personally I find the uniformity makes it harder. But maybe that's just what I'm used to. As an aside, I find c major a horrible key to play in, again I think the uniformity makes it harder and less ergonomic, but…

Absolutely.

Another data point: I play the organ, which involves playing a large keyboard with your feet (https://en.m.wikipedia.org/wiki/Pedal_keyboard). The structure of black notes is crucial to being able to play without looking (which is important because you’re simultaneously doing various other things). Concretely, I couldn’t imagine playing the organ without being able to slam my foot into the right hand side of a B flat in order to know that my foot is on top of the B. If you watch an experienced organist’s feet you’ll see them do this all the time.

I also find C major horrible.

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