/sqt/ - simple questions thread (aka /qtddtot/)

Previous thread: >>16683085

>what is /sqt/ for?
Questions regarding maths and science. Also homework.
>where do I go for advice?
>>>/sci/scg or >>>/adv/
>where do I go for other questions and requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt etc.
>how do I post math symbols (Latex)?
rentry.org/sci-latex-v1
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
scholar.google.com
>where can I search for proofs?
proofwiki.org
>where can I look up if the question has already been asked here?
warosu.org/sci
eientei.xyz/sci
>how do I optimize an image losslessly?
trimage.org
pnggauntlet.com
>how do I find the source of an image?
images.google.com
tineye.com
saucenao.com
iqdb.org

>where can I get:
>books?
libgen.rs
annas-archive.org
stitz-zeager.com
openstax.org
activecalculus.org
>articles?
sci-hub.st
>book recs?
4chan-science.fandom.com/wiki//sci/_Wiki
math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>online courses and lectures?
khanacademy.org
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com
www.chemspider.com

Tips for asking questions here:
>avoid replying to yourself
>ask anonymously
>recheck the Latex before posting
>ignore shitpost replies
>avoid getting into arguments
>do not tell us where is it you came from
>do not mention how [other place] didn't answer your question so you're reposting it here
>if you need to ask for clarification fifteen times in a row, try to make the sequence easy to read through
>I'm not reading your handwriting
>I'm not flipping that sideways picture
>I'm not google translating your spanish
>don't ask to ask
>don't ask for a hint if you want a solution
>xyproblem.info

Is it retarded to get a STEM bachelors to be more employable even though your passion is outside of STEM?

>>16724679
The answer for any extremely broad question like this is always going to be "it depends."

My advice for you is to only do this if you actually have an aptitude and interest in some STEM subject. I've known quite a few people go to college for CS just because of the lucrative job market, only to find out that they aren't good at programming and they don't care about computers, and then their degree is essentially a $40k piece of toilet paper.

If you're go to college to study something that you hate you'll never get good enough at it to find employment in that field and even if you do you'll hate doing that job, and you probably won't even have time for music/art/jacking off/whatever else your "passion" might be.

>>16724711
I think my talent is average, and my interest is genuine. It's just, I'd rather be remembered for writing a great novel. I just know that you don't really need to go to college to write a great novel. However, having good income while your writing makes no money is a very good thing.

If science is so important to society, why do people like Terence Tao make less money than Brad Pitt or LeBron James?

>>16724976
Importance does not equate to market value. For example, your father who taught you to work hard or your mother who nurtured you so you wouldn't be a school shooter performed a service that provided all of the value of your entire life, and they got paid (or paid, if you turned out to be fucking worthless) nothing.

any easy ways to get real access to journals?
some public libraries also have access, for example

how else

>>16725023
Walk into a college and pay a student ten bucks to use their login for a few hours.

why are opensource fem solutions either complicated or complete dogshit? I wanted to recreate a work my prof did and wasted two fucking days playing around only to conclude that freetools cannot compete. All the free simulation tools seem to target a certain niche and its never aligned with your research...

Is science even worth it nowadays? Should I just join the trades? A robot's just going to be able to take water samples or mix chemicals in a few years anyway.

What are some mindblowing books on biology? I want books with math in them. Tell me of biology books.

>>16725054
discovery and optimization preceeds automation and manufacture, robots may do undergrad level work, but even in worse case scenario, quality control and setting will be done by humans, less educated you are, more likely you are to be replaced, blue collar trade jobs are being automated for decades and that trend will continue

There exists the ability to recall sound and create music inside of the mind, some people can imagine an apple inside of the mind, yet is there a group of people who can pontificate the odoriferous emanations within the mind space?
That is, ergo, vis a vis, can they create scent and smell, imagine smells, within the mind?
And are some smells and scents stronger and thicker and larger to imagine than others?

Can someone explain to me how I figure out, on the fly, how to decide how many digits to round to if not explicitly explained in the assignment?
My professor mentioned significant figures and while I know how to count significant figures that doesn't tell me if I should round to the hundredths or the thousands or what.

>>16725108
Yeah but a robot that can maneuver around unfinished without falling is more expensive than paying death benefits, workers' comp, and wages to a worker.

>>16725194
If it's not specific in the question it doesn't matter.

>>16725194
now here i may give a dumb answer, but if question mentions what youre measuring, you need to think about it, if your figures involve tons or hectolitres, if your answer includes every gram or mililiter, you may be giving values so specific that they are redundant, but than again, it really, really depends on the assignment

Okay, so I know mass and weight are different things and metric is king, blah blah blah, but since most normies aren't going to say 'my weight is 9.8*x(prefered unit)' and 'my mass is x(preferred unit)', can we just accept that arguing about mass and weight with normies is stupid and it just turns people off?
Like normies aren't talking about your weight on the moon, ever.

>>16724976
because society doesn't value value to society.

>>16725264
Society values value to society but if the guy who invented epipens asked to be paid their worth as a value to society we'd still be printing money to catch up.

Taking science classes with lab components online is a mistake. That is all.

I have a question about spectrometers. Always been around them at work (industrial fluid processing, automated stuff, piping networks, etc...) in the lab environment, mostly. Occasionally, there would be something like an in-process spectrometer for essentially checking that a pre-dyed ingredient was added to the correct amount in a flow/batch process.

My thought here is this-

What would be the useful accuracy of a benchtop liquid flow-through spectrometer with an 8-solenoid valve manifold for the input and an 8-solenoid valve manifold for the output. Have a recirc pump there in the loop with a quartz tube as the optical element along with all the attendant diffraction gratings, mirrors, lenses, etc...

I've read a few papers where a fiber optic strand is used as a contact probe into the solution under test, sometimes with a corner retroreflector inside.

My application is for measuring the specific mineral and fertilizer concentrations for a vertical gardening/nutrient film outdoor container garden. My concern is that the setup just will not give the type of accuracy I need to measure things like potassium to the +-10ppm level, alongside other spectrographically significant signatures that can be read on backend software.

I know of extremely expensive setups which can do this, but it is even remotely approachable at the $1,000 price point? It seems like it would be a very valuable tool in tracking and operation of a container garden, alongside the plots of rain, temperature, etc...

>>16724182 (OP)
Is it strictly coincidental that Oumuamua and 3I ATLAS came in at nearly the exact same x and y axis, as they passed the orbit of Jupiter?

Anyone else notice that one funny little detail?
Oumuamua fast, sharp Z axis entry from state of rest zone.
3I ATLAS following just a few years later, but specifically coming in at an angle near our solar plane, and obscured by the dense are behind it, as viewed by Earth.

Guys I'm not going to lie, it really looks like we just got scouted(Oumuamua), and now they are sending the bigger thing in(3I ATLAS).

Game theory it up, but that's what we have going on.
Small fast thing from zone of rest, scouts, leaves fast.
Bigger thing coming in, similar trajectory at Jupiter orbit, but doing its best to come in stealthy from the dense zone of the Milky Way behind it, from Earth observation angles.

Mr. Star, I don't feel so good.

I like to calculate tips in my head when I run. It’s easy and occupies my mind. I just move the decimal to the left and double the result.

Are there any other cool little math tricks I could do in my head when I run?

t. mathlet

>>16725054
Who decides what the robots should do?

>>16725194
Whether adding or multiplying, the answer has as many SF as the involved term with the fewest.

>>16725572
The person in charge of the operation, who is probably either a government bureaucrat or a MBA holding business guy.

Why does a L1 penalty term actually promote sparsity?
And please don't give me that bullshit geometric explanation.

>>16726067
When you are minimizing with a quadratic loss, there is not much benefit setting a coefficient to zero because due to the quadratic term the decrease in loss gets smaller and smaller as the coefficient gets small. With l1 loss, the decrease is linear and so, even as the coefficient gets small, it remains just as valuable to decrease the coefficient size.

>>16726095
Thanks, but that only explains why L2 does not help with sparsity.
I still need a good reason why L1 improves it.
I have a feeling it has something to do with it's subgradient and how you calculate with it, but I don't have any good sources for this theory.

Education is /sci/, right?
So I read in "Misfile" webcomic that girls are discriminated against in a math class by math teachers. I immediately thought it was unrealistic bullshit and dropped the comic.
But now that I think about it, maybe it's an American thing?.. In my country all math teachers are always female. Boys are known as hooligans by teachers, and girls are often teacher's pets, math included.
So, if you life in America, how true it is?

>>16726105
Well l1 penalty is not special in that sense, the same logic applies to sub-linear penalties as well, e.g. using |x|^p for 0<p<1. These are no longer norms, but they stimulate sparsity more heavily as p decreases, in fact you can use the l0 penalty that counts the number of non-zero entries and this stimulates sparsity the most.
I do think the geometric picture helps actually as to why l1 penalty promotes sparsity. In picrel you can see the l1 ball slopes down somewhat narrowly from its ridges. The unpenalized minimum location is most likely away from the l1 ball and when you introduce penalization and constrain the location to lie in or on the l1 ball, the minimum location will most likely be on the ridges of the ball. This is because the ball slopes down fast from its ridges so if you are going down from the ridge you are changing the coefficients drastically and will not end up at the constrained minimum most likely.

The subgradient has something to do with what I said already. The subgradient of absolute value is step function and so the subgradient is constant, until it flips sign. So you keep making the same steps in the negative direction of the subgradient, regardless of how big the coefficients are, unlike quadratic case where the gradient steps become smaller.

If a unit square is divided into seven regions each having equal area, what is the minimum total length of all the region borders within the square?

>>16726138
Thanks for your take on this, but I still feel like the geometric explanation is bullshit.

/r/ing a third anon to give his opinion on all this.

>>16725127
I can do all the things you're talking about. Phonographic memory and auditory imagination, check. Apples and other objects, check.
Scent? Very easily, though intensity is a bit dulled, I can imagine some bad smells but it's harder to remember just how bad they were.
Is this really an uncommon trait? I thought memory and imagination were generic and happened on the qualia level.

>>16726107
Obviously there's a lot of room for variance, but overall such a scenario doesn't seem unrealistic. There's something of a stereotype that females are worse at mathematics than males (even though more and more studies are showing less and less of a gap). Could definitely see someone with that at the back of their mind giving preferential treatment to male students.
It doesn't have to be actively antagonistic to be discrimination, either. I've heard about teachers who will give a struggling male an actual explanation while the struggling female only gets "reassurance" that it's a difficult subject and that it's okay for them to find it hard

>>16726158
What's your issue with a ("the") geometric explanation?
An L1 ball has few extreme points, and each one of them is a "sparse point".

>>16726592
Mostly because my instincts are telling my it is nonsense.
Why would the solution always be conveniently located somewhere close to an axis?

>>16726896
>always
That's not the case. If you add a regularizing term [math]\alpha |x|[/math] then for sufficiently small values of [math]\alpha[/math] your solution won't be sparse. As you regularize more (increase [math]\alpha[/math]) the [math]x_j[/math]s one by one become zero.

>>16726896
The contours of the objective function are more likely to hit a corner point or ridge of the diamond shape, which will result in both cases in some coefficients being zero, than they are to hit a point of a sphere where there is sparsity. Picrel shows this for the corners, but for the ridges it helps to think in 3d. In 2d only the corner points set coefficients to zero, in 3d the ridges do so as well.
Think of it as the unconstrained minimum location pulling the coefficients to them, while the penalization is pulling the coefficients back to the l1 ball. With the geometric picture in mind, you can see why the constrained solution is more likely to lie on a corner or ridge and these points induce sparsity.

>>16726941
>in 3d the ridges do so as well
Ah, shit, I see it now. Thanks.
I think all those bad explanations I read in some papers kinda prevented me from seeing it.

And >>16726138 were right as well. Thank you, too.

>>16724182 (OP)
is this better than r/Scholar or whatever?
https://sci-net.xyz/

So I got a physics book.
What's a good place to actually...well, figure out how to apply what's written? I'm in a class but sometimes I feel like the book says XYZ and the online thingie asks for ABCKL

>>16727919
Have you considered the exercises written in the book?

>>16727953
No.

>>16726107
It used to be the case in America that girls were not expected to have a career in which they would need math more complicated than arithmetic, so if a girl was not doing well in trigonometry then there wasn't a compelling reason to spend effort teaching her, and if she went to university then it wasn't going to be for something in which calculus was necessary
The mathematics that women needed to be teachers was taught at the teacher's college and the more important quality was to be able to control the classroom
As a child grew older, more of their teachers would be men and these men had better educations than the female teachers
It's not so prevalent now, girls are overrepresented in universities in America (except for a few fields in which strong mathematical foundations are necessary)
Even the mathematics departments in universities have lots of female students because they were encouraged by their teachers growing up, and this portion will probably increase with time as the residual attitude of the last centuries goes away (ideas last longer than people do)
My recollection of university was that the math department had more female students than the computer science department, but whenever I see pictures of national delegations to international math competitions, the teams are entirely or mostly male, so maybe at the very top level of human ability (far above what I could ever achieve) there are sex-determined differences in mathematical ability
>>16725052
Particularly for software with narrow user bases, somebody has to either get paid to care about it, or otherwise benefit from the time they spend making and maintaining it-- probably your software was extensively cared for for four years while some guy was getting a PhD off of it but when he graduated he had more profitable things to do
>>16726150
Can you provide some more constraints? Because otherwise I can just plop in a Koch star as one of the regions and then the border length is infinite

So I'm lost in the woods here.
I was trying to be a good lad and calculate friction into downward acceleration on a ramp because we're learning friction this week. I'm either overthinking it, retarded, or both.
My variables:
The angle is a downward ramp that does down at 9 degrees.
Gravity is positive since we want to go down the ramp.
The kinetic friction coefficient is 0.3.
So, unless I'm pants on head:
a = 9.8(sin(9) - 0.3*cosine(9))
a ends up being a negative value, which since we're going downward isn't right.
Am I stupid? Because smooth steel balls don't fail to roll down wooden ramps, and they certainly don't roll upward on their own.

>>16724182 (OP)
Is mensa norway accurate? I got 120 on it

>>16728742
Is mensa really something you want to impress? Also, while Norway is a civilized nation, does anyone care about it outside of Norway?

>>16728742
No online iq test is accurate.

/med/ anons this is not a call for a diagnosis or any severe medical condition just some curious feature I noticed.

I get these odd spots sometimes,
Just behind the ear there's like a bone ridge, about 1cm after this ridge I have a semi paifull spot/zit, but currently in the exact same place behind both ears.
Just wondered if there was any plausile explanation for the placement like some lymph node or somethiing since they seem to reoccur at the same point?

>>16728863
Have you had this before? How often?

>>16728901
every couple of months usually I don't really pay attention anymore only this time they're both on roughly the same spot but either side of my head.

>>16728915
Have you reported this to a doctor before?
Are you too poor to just go to your annual wellness visit and point it out? I mean, if it's not a serious medical condition, your doc gets literal free money from the insurance company to prod you once a year.

So, I think I'm starting to get significant figures, but I'm not sure I understand why you use them. Even if, for example, I have a scale that only records to xxxx.y, if I can retrieve more accurate results for other parts of the equation I don't see any reason I should make the final answer more inaccurate just because my scale is a piece of shit.

I just need to complain. Why do we keep using greek letters instead of writing out what we mean? It's not like ink is a rare commodity now, and for digital print media you literally lose nothing by adding more pages.

>>16729487
Why is any notation invented? To make it easier to read and understand concepts. Any non-trivial statement becomes extremely long when we write it out in words.
Similarly, why do programmers not write in binary? Why add language and notation on top of it when storage space is rarely a limiting factor of the length of a program?

>>16728974
No not really, the spots seem to come and go I think my diet affects them.
they aren't pussy but more a painful raising.

Sex with Gaussian integral

>>16725025
>>16725023

Or install a keylogger at your local university's computer room, that's what i did

What would happen if there was a huge chuck, maybe a few kilograms of a radioactive metal like astatine, having half life of eight hours? Would it glow red hot from the radiation, or would it explode, etc? And what would be the ramifications of that much radiation released?

>>16729592
I mean, do universities even have computer rooms any more? I thought they just raised tuition by x and sold laptops for x-y in most cases now.

>>16729593
Well it would throw out a *lot* of alpha radiation which would be harmful at best, deadly at worst depending on proximity. It would not explode, radioactive decay never does. Heat would be generated simply due to the kinetic energy of the alpha particles interacting with the material but probably not enough to glow. After a day or two you would simply be left with a lump of lead or bismuth depending on the exact decay chain.

>>16729615
>I mean, do universities even have computer rooms any more?
Yes.

Is there software to bypass patreon avaliable?

>>16729965
You have no idea how websites work do you.

>>16729667
>Well it would throw out a *lot* of alpha radiation which would be harmful at best, deadly at worst depending on proximity
brainlet moment
external alpha radiation is harmless, it doesn't penetrate the skin

>>16729965
not for free

>>16730079
In general that is true but in high enough doses it is strongly ionizing and can still externally cause damage to someone's chromosomes.

Hi, whats the formula to calculate the velocity of an electron in a homemade electron accelerator using a power source of 20kv and a vacumm of 1399.881 pascals

>>16725448
It'll be like 75000 years until these objects go to other solar systems, relax

>>16730067
How?

>>16730192
All the logic and software that controls who can access what is stored on their servers. There is nothing you can install to bypass that.

So use someone else's credentials or actually pay people for their work.

>>16730216
Shut your ass up, nigga.


I ain't paying anything.

>>16730253

>>16730255
https://github.com/pkkyrtw4346273/UPDATED/blob/main/Patreon%20Viewer%20Tool%20to%20see%20Patreon%20content%20for%20free%20without%20a%20subscription.md

Saw this before, not sure if it works.

What is the scientific name of this creature?

What percentages of the coastline of the Caspian Sea do Kazakhstan, Russia, Azerbaijan, Iran, and Turkmenistan have?

Please answer in a pie chart
(1) which is labeled with the percentages and countries,
(2) which is in geographical order (like a map),
(3) in which Iran is at the bottom (just like on a map), and
(4) which I can download.

>>16730862

>>16730863
The Caspian Sea is bordered by five countries: Kazakhstan, Russia, Azerbaijan, Iran, and Turkmenistan. Based on available data, the approximate coastline lengths and their corresponding percentages are as follows:

Kazakhstan: 2,320 km, approximately 32.3%
Turkmenistan: 1,768 km, approximately 24.6%
Russia: 1,355 km, approximately 18.9%
Azerbaijan: 820 km, approximately 11.4%
Iran: 728 km, approximately 10.1%

These percentages are calculated from a total coastline length of approximately 7,000 km, as cited in some sources, though estimates vary slightly (e.g., 5,970 km in another source). The percentages are derived by dividing each country's coastline length by the total and multiplying by 100.

Below is a pie chart representing these percentages, arranged in geographical order with Iran at the bottom, as requested. The chart is labeled with countries and their respective percentages. You can download the chart by right-clicking on it in the interface where it is displayed or by using the download functionality provided by the platform.

Grok can make mistakes. Always check original sources.
Download

Explanation:
Labeled with Percentages and Countries: The chart labels each segment with the country name and its percentage (e.g., "Iran (10.1%)").
Geographical Order: The countries are arranged in a geographical sequence, starting with Iran at the bottom (south), followed by Azerbaijan (southwest), Russia (northwest), Kazakhstan (northeast), and Turkmenistan (southeast).
Iran at the Bottom: The rotation option is set to -162 degrees to position Iran at the bottom of the pie chart, aligning with its geographical position on a map.
Downloadable: The chart can be downloaded via the platform's interface (e.g., right-click or export options, depending on the system).

>>16730863
Did you make that chart? Cool

>>16726941
>[[[cost]]] function
its a function, there is nothing special about it
it doesnt deserve any adjective

>>16730998
This is what you nitpick? Boohoo, in the context of regularized regression, where there is a cost function and a penalization term, the pic called it a cost function.
Was it absolutely necessary to call it that? No.
Does it matter at all? Not even in the slightest.

>>16730905
>Did you make that chart?
grok.com made it

there are a lot of insults on 4chan.org
but grok.com never insults its users

and grok.com pays attention to every word in the user's input or prompt

and grok.com often gives detailed answers

but one of the bad things about grok.com is that it only gives "politically correct" answers
i always want read the most politically incorrect answers
in other words, grok.com spews propaganda
there's also a lot of propaganda on 4chan.org

what should i be doing outside of reading textbooks and doing the practice problems in them to learn math well?

Good free sources of information for learning about physics and engineering? I already know about openstax.
>>16731312
Finding a practical math application to your own life.

Not sure if I should ask /diy/ or you guys but here goes:

My shower drain was draining very slowly so I poured some limescale remover down it, then when I came back like 2 hours later my bathroom REEKED of sulfur, like Satan had eaten a thousand boiled eggs in it, what does this mean?

What causes mercury to be the least heat conductive metal?

>>16733018
Same reason it's a liquid at room temperature. Weak bonding between the atoms.