Stupid Questions September 2016

by pepe_prime1 min read5th Sep 201633 comments

6

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This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.

Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.

To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.

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Do you think it would be easier for you to untangle your earphones if the cord had a color gradient? Maybe something like the jack end is violet and the bud end is red, and it goes through the entire visible spectrum along the length of the cord. Could also be something like a grayscale gradient. I imagine it making it easier for me to simulate untangling strategies. Surprisingly there are basically no earphones that look like this even merely for aesthetic reasons.

Also, I'm already aware of ways to prevent tangling.

If money is not an issue, wireless headphones is probably at the top of my improve my life for less than $50 list.

You don't have to worry about untangling, putting away or unplugging.

I recommend the ones that sit on your neck like these

Even if money is an issue, it's not that expensive.

I bought 2 from this site and they arrived about 2 weeks later. They are the same exact headphones as my branded ones. Very happy for paying $4 each. Thanks.

EDIT: I have determined that these headphones are not the same quality, the battery of both pairs I bought are about 1/5 the life of the branded ones. There are not of similar quality, but the price was still very good.

oh wow, that is cheap, thanks. I don't have experience in buying generic electronics from china. Is that legit?

I did buy a phone charger from China that does what it's supposed to do. In this case I think the product is likely produced in the same factory as a similar product you would buy in the US but it's more directly sold by a factory instead of intermediaries taking cuts.

Thanks I actually ordered a few from the site because I also think as you do that the product is probably made in the same factory. I happen to own the LG branded ones, and would be very happy if these are of similar quality.

While being aware of various ways to solve this problem. Mine is to fold the cable in half, then half again, then half again until it's small enough to go into a pocket. Then store it somewhere where it will not get moved around very much, and be encouraged to tangle. The only disadvantage is that this doesn't always suit the twist of the cable, so the cable will sometimes twist around itself a few times, but never form a knot (in my experience).

You might find that owing to manufacturing process, multicoloured cables are a bit of a pain to make. We usually make very long rolls of wire with identical sleeves. Then cut down the wire to make relevant size pieces. This idea would require doing things differently.

That's an interesting idea and yes, I think it would help. It seems you can find cable sleeves in this style, though I'm only seeing them in bulk.

Yeah, I've seen things like that. The problem there is that the colors cycle. The point is to provide an unambiguous visual cue of where along the length of the cord a given section of cord is. If the colors cycle, then two locations can have the same color, undermining the utility of the cue. A few other products come with a gradient on the cord, but the endpoints barely contrast; say a light yellow-light orange gradient.

How about these? They have 3 colors and don't cycle.

Matrix multiplication

Could somebody explain to me, in a way I'd actually understand, how to (remember how to) go about multiplying a pair of matrixes? I've looked at Wikipedia, I've read linear algebra books up to where they supposedly explain matrixes, and I keep bouncing up against a mental wall where I can't seem to remember how to figure out how to get the answer.

1 The mental image I have, which may or may not be helpful to anyone else, is of a row of the LH matrix sliding over and rotating clockwise until it matches a column of the RH matrix.

2 If you don't mind working it out from scratch and have a more "algebraic" than "geometric" brain, the following considerations may help:

  • Matrices are indexed row first, then column (think "reading order": if you think of the indices as numbers, then as you read along rows like reading a book they increase monotonically).
  • When you multiply matrices, what happens is that "middle indices match": element (i,k) of the product is sum over j of left[i,j] right[j,k]. See how the j's match up and "cancel out".

3 The product matrix is an array of inner products of rows from the LH factor and columns from the RH factor.

I make no guarantee that any of those will help, but if any of them seems to be heading in the right direction but not getting there I'm happy to try to adapt further...

Low confidence that this will help, but my approach: I mentally move the right-hand matrix up, so that the space "in between" them (right of the first, below the second) is the right shape for the result. Each value of the result is the dot product of the vectors to the left and above it. (I don't have a trick for dot products, I just know how to calculate them.)

. . . . g h i
a b c * j k l
d e f . m n o

"becomes"

. . . g h i
. . . j k l
. . . m n o
. . . -----
a b c|S T W
d e f|X Y Z

and e.g. S is (a b c) dot (g j m), Y is (d e f) dot (h k n).

By Juniper, I think this is the one. It's simple enough that I can actually remember this, and I can solve arbitrary matrixes with this approach.

Feel free to have an internet cookie in thanks. :)

I use exactly the same approach! When you position the matrices this way, it becomes completely obvious.

Perhaps explicitly thinking of them as systems of equations (or transformations on a vector) would be helpful.

As an example, suppose you are asked to multiply matrices A and B, where A is [1 2, 0 4, -1 2] (the commas represent the end of a row) and B is [2 1 0, 3 1 2]. Start out by taking the rightmost matrix (B in this case) and converting it into a series of equations, one for each row. So since the first row is 2 1 0, the relevant equation will be 2x + 1y + 0z. Assign each of these equations to some other variable. So we now have

X = 2x + y

Y = 3x + y + 2z

Now do the same thing with the matrix on the left, except this time use the new variables you've introduced (X and Y), so the three equations you end up with (one for each row) will be

X + 2Y

4Y

-X + 2Y

Now that you have these formulae, substitute in the values of X and Y based on your earlier equations. You get

(2x + y) + 2(3x + y + 2z)

4(3x + y + 2z)

-(2x + y) + 2(3x + y + 2z)

Simplifying, you get

8x + 3y + 4z

12x + 4y + 8z

4x + y + 4z

The coefficients of these equations are the result of the multiplication. So the product of the two matrices is [8 3 4, 12 4 8, 4 1 4].

I'll admit this is not the quickest way to go about multiplying matrices, but it might be easier for you to remember since it doesn't seem as arbitrary. And maybe once you get used to thinking about multiplication this way, the usual visual rule will start making more sense to you.

It's a 50-50 arbitrary convention.

I suggest physically tracing through the matrices with one finger from each hand. As you would multiply If you do it the right way enough times, doing it the wrong way will feel weird.

Also, the canonical example is y=Ax, with A a matrix, and x,y as vertical vectors. If you can at least remember that one goes vertically, and one horizontally, Ax will show that it is the one on the right that goes vertically.

As I understand it, if I buy a chicken in a supermarket, this causes approximately one chicken to be killed; and similar for beef etc, adjusting for the amount of meat versus the size of the animal.

Does anyone know how this number changes with discounts? I'm specifically thinking of the thing where my local supermarket reduces the price of things when they're approaching their expiry date.

As a person who has read less than 10% of the sequences would it be bad of me to want a quick conclusions of each chapter? Would I be losing anything if I didn't need to be convinced, I just want to know the pointers?

As a person who has read 100% of the Sequences, I would also prefer if there would exist a shorter version. But, as far as I know, it doesn't exist yet. Someone would have to make it. Someone other than Eliezer, because this is not at the top of his priority list.

Would I be losing anything if I didn't need to be convinced, I just want to know the pointers?

You would be probably more likely to forget them. In general, longer text requires you to spend more time focusing on the idea. If someone would convert the Sequences into a PowerPoint presentation of 20 pages, a week later you probably wouldn't remember anything.

I realize how what I wrote here conflicts with my desire to have a shorter version of the Sequences, and... I don't know. Perhaps the shorter version should use other techniques for easier memorization, e.g. funny pictures.

Rationality is about not simply taking up believes unfiltered but evaluating claims of other people before you believe in them. Not doing that would seem to miss the point on a general level.

Accepting conclusions that have been accepted by a sufficient number of marginally trustworthy people is not necessarily a bad heuristic. He might gain more from dogma if he won't persevere through the reading, though a list that people are publically being pointed to could lead to people pointing fingers, saying "cult".

I think the value of the sequences is that they change heuristics of thinking that many people who read them use. I would guess that you don't get that value by simply reading conclusions.

[-][anonymous]4y 2

Ego is an enemy of happiness and productivity.

How can I overcome ego related to relationship quality, stress, health, career, egolessness, psychological skills, attractiveness, intelligence, victimhood, effort/work and pleasure?

How do you insert an image in a post here?

I pulled up the wiki to see if i could upload, and then link to it, but can't get post auth.

Is it just /img?

I think you can't add images to comments. As far as posts go, I think it's html tags.

[-][anonymous]4y 1

About to quit another job slash offer and dump my first chick. A win for self respect: I tried to change gear for an upcoming night shift - my first. Instead, I have decided I will resign instead of taking this job since it entails too great a compromise on my social lifestyle and health. I win the best in bed award today 😏 I spent almost all today in bed. I had the chance to pay attention to my thoughts. I learned that 90% of my thoughts seem to be unproductive and unpleasant worrying. What are some technique to eliminate worrying?

This quote helps me recall that rationality isn't about worrying - which is so easy for me to forget:

''Remember that the term Rational was intended to signify a discriminating attention to every several thing and freedom from negligence; and that Equanimity is the voluntary acceptance of things which are assigned to thee by the common nature; and the Magnanimity is the elevation of the intelligent part above the pleasurable or painful sensations of the flesh, and above that poor thing called fame, and death, and all such things. If then, thou maintainest thyself in the possession of these names, without desiring to be called by these names by others, thou wilt be another person and wilt enter into another life.'

I have another lesswrong.com editor question. I posted a discussion article for almost the first time. I'm having trouble making my section headers be bold text. I can do it when i save an article to drafts, but when i edit my article the boldness doesn't save. I used the 'bold' button in the editor.

Any advice?

I'm having trouble sending a text message with an ipad and iphone? The recipient isn't receiving the text. What are the sources of error other than wrong number? Also, are you supposed to input the 1 before the 10 digit number? It's U.S. to U.S.

What's the recipient using, and did they previously use something else? If they switched from iPhone to not-iPhone, there's a bug with Apple's iMessage that could prevent them from receiving texts. https://support.apple.com/en-gb/HT204270