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/sci/ - Science, Technology, Engineering, and Mathematics

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New Textbook/Book Request Thread deadbabies ## Mod ## 13/08/25(Sun)06:03 No. 15270 ID: f34135 [Reply] Stickied

File 137740339172.jpg - (401.45KB , 1680x1050 , titanfalsecolor.jpg )

First off, hello there, I'm deadbabies, and I will be taking over as /sci/ moderator. Rules will remain the same. Please use the report function if you see posts that violate the rules, but also do not abuse it.

I have officially expanded the scope of /sci/ a bit. You may discuss Science, Technology, Engineering, and Mathematics here now. No science is discriminated against as long as it's of the peer-reviewed variety. If someone wants to discuss Anthropology or Social Science, by all means, let them. If you do not like it, just don't post in the thread.

The IRC channel #/sci/ is now (finally) re-registered and I am running as operator on here. Feel free to stop by and say hi. I do leave my computer idling on IRC, so check back or leave me a message if you have any ideas, suggestions, or just want to tell me off. You can get onto #/sci/ by joining the server irc.7chan.org at port 6667. You can also use SSL at port 6697 but you will have to set your client to accept invalid certificates.

ADDITIONALLY and IMPORTANTLY I have had several requests on IRC regarding the old Ebook FTP that we used to have. Unfortunately, the mod who ran it entered the military and no longer runs or maintains it. I have no plans to make another one, but if one of you guys would like to, by all means advertise here.

That being said, I'm just going to leave this link here:


You may find what you seek here.

I will be unstickying the old ebook/source articles thread. Please post any new ebooks/source articles here, and feel free to post any working links from the old thread there; I will eventually be deleting it.
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Anonymous 22/03/30(Wed)11:10 No. 18253 ID: c28a48

How cool that now you can earn good money from the comfort of your home thanks to technology. I mean betting. Previously, people had to go to bookmakers to place a bet, now I just need to go to the site https://www.dimers.com to make a quick bet, look at match predictions or choose a reliable betting site.

Prime test Anonymous 22/02/17(Thu)19:25 No. 18131 ID: f85074 [Reply]

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Today one of my recurring dream characters named Jennifer Zemblini gave me a prime number test that correctly validated the first few hundred prime numbers in under 3 seconds using C# code I wrote to validate her primality test!

I wanted to share the primality test with you all now.

It uses only simple division, addition and subtraction. And three variables called n, A and B.

n is defined as the number being tested for primeness. A0 is n-2 and B0 is 2.

Then apply this procedure: Divide A by B, if it is not a clean division, meaning there is a remainder, add one to B and subtract one from A, and repeat this step until B approaches one-half of n.

If A can never divide evenly into B then n is prime.

For example with n=9, which is not prime: A = 9-2. B =2. 7/2 is not even. 6/3 does evenly divide with result 2. And 3 is a factor of 9 also.

But for a prime like 13: 11/2... 10/3... 9/4... 8/5... 7/6... None of these divide cleanly with no remainder, therefore 13 is prime.
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Anonymous 22/02/21(Mon)05:14 No. 18141 ID: bf7eac

Oh, that's great. Fucking bbcode.

Anonymous 22/02/21(Mon)05:31 No. 18142 ID: bf7eac

Ah, got it.

n is divisible by m if and only if n + m * k is also divisible by m, where k is any integer value. This is deducible from the definition of division in integer arithmetic:

(Reminder: the dividend is the left-hand side operand for / and %, while the the divisor is the right-hand side.)

quotient * divisor + remainder = dividend
(dividend = n + m * k, divisor = m, remainder = 0)
quotient * m + 0 = n + m * k
quotient * m + 0 = n + m * k
(quotient - k) * m + 0 = n
quotient2 * m + 0 = n
quotient is still zero when dividend = n, thus n % m == (n + m * k) % m for any integer k.

In other words, testing whether (n - a) % a == 0 is equivalent to testing n % a == 0, and testing all the way up to n / 2 is valid as long as n / 2 >= sqrt(n), so the test is actually invalid for n < 4 and could return a false positive. It just so happens that both 2 and 3 are prime, so there's no room for false positives in that range.
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Anonymous 22/02/21(Mon)05:33 No. 18143 ID: bf7eac

>quotient is still zero when dividend = n, thus n % m == (n + m * k) % m for any integer k.
This is an error. I meant to say that the remainder is still zero.

Old Technology Thread Anonymous 21/02/10(Wed)07:42 No. 17263 ID: 2c3397 [Reply]

File 161293936437.jpg - (53.38KB , 584x640 , s-l640.jpg )

ITT Post/discuss old technology.

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Anonymous 22/01/30(Sun)13:35 No. 18088 ID: 9d1214

File 164354612636.png - (452.22KB , 683x513 , photo.png )


LOL that pic reminded me of pic related.

Anonymous 22/04/16(Sat)01:20 No. 18264 ID: ed4fef

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My Gameboy Camera with a pic of my buddy, Clay.

The+Red+Barron 22/05/16(Mon)09:29 No. 18273 ID: 7cb4c3

Bought a PS1 a week or two ago

Fucking love it

Anonymous 21/11/30(Tue)15:25 No. 17940 ID: 3cad9e [Reply]

File 163828230323.jpg - (2.03MB , 2141x1825 , IMG_20211130_212530.jpg )

isnt ther ways to draw like this?
basically knowing how long the lines go and where it start and goes to at any time and any moment, to represent the subject in perspective as correct as possible?

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Anonymous 22/02/24(Thu)11:49 No. 18159 ID: 0d8deb

File 164569976332.jpg - (58.17KB , 515x630 , 9781933492735_p0_v2_s1200x630.jpg )

"How to draw" from Scott Robertson, who is an industrial designer / vehicle concept artist, should cover almost everything.
Make sure to follow the exercises.

Satan 22/05/02(Mon)22:37 No. 18266 ID: 108569

Nice art, Ryan.
Too bad Derek has no skills.

The+Red+Barron 22/05/16(Mon)09:27 No. 18272 ID: 7cb4c3

Damn, that fucking tractor on the cover is epic

A Typical Elon Musk Day...but it could take place at another tech company. Mr Musk 21/05/22(Sat)08:10 No. 17563 ID: eed8a3 [Reply]

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A Typical Elon Musk Day...but it could take place at another tech company.

Telsa Software Developer: Good morning team, Elon did not like that it took his model S 17 minutes to get to the car factory from his house last month. So I built him a rocket ship. It takes 10 minutes off his commute and only burns $100,000 of fuel each way. Operations, we need a voice activated rocket landing pad on the factory's roof quickly as this is an expensive project.

Telsa Operations Manager: Hello sir, this is the first I heard of this, I just spoke to my engineers, and if you land that massive rocket on the roof, they are 100% certain the entire building will collapse, killing us all. Have a great day.

Telsa Architecture Manager: Team, we architected that elevated personal super highway for Elon last month it cost 90 billion, but I will see what else we can do. We do need a few months to think about rocket landing pads before designing the most elegant thing possible otherwise it will be too easy to implement, and we can't have that.

Telsa DevOps: We have an AI electric helicopter for Elon, it will take 5 minutes off his commute and does not use any fuel as it runs on solar power. We told quality control to look at the windshield, and it is bug-free literally. Give us 2 years and we can take another minute off of his commute by tweaking the helicopter pipeline.

Telsa UX: Sorry, DevOps, behavioral science tells us Elon likes rockets because of the little red on one on his childhood lunch box.

Data Science/AI Manager: Team, our predictive models show, If the rocket lands on the roof, it will take ~5 seconds, not 6 seconds, for the building to collapse and burst into a giant ball of fire. We are 99.3347534% sure of that, accounting for wind speed and 10,000 other variables. My PHD's do worry about sample size in our AI algorithms (Ivy league Doctorates worry about everything) ... so they are asking a few rich princes they met on the dark web to donate their spare space rockets for experiments. All we have to do is send each prince $100 dollars for rocket shipping and we can improve our machine learning by a factor of 6.43.
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SamanthaFix 22/03/02(Wed)11:16 No. 18169 ID: f9af09

I think he has a big future

Satan 22/05/02(Mon)22:35 No. 18265 ID: 108569

You stalking Elon Musk through his devices?
And Grimes is trying to kill him?

Roulette JackJackson 22/04/15(Fri)13:18 No. 18263 ID: a1b75d [Reply]

Youtube  Guys, I need advice. I like to play roulette and I always think about how to make my game safer. You can earn money on it if you are a disciplined gambler. I usually play using this casino https://onlinecasinosrealmoneycanada.com/ if it's important. So smart guys, I'm waiting for you in my thread.

Is cold air denser than hot air? Anonymous 18/02/27(Tue)19:46 No. 16630 ID: dfa669 [Reply]

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Plz help

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Anonymous 18/03/02(Fri)04:56 No. 16632 ID: 6914e6

volume = mass / pressure * temperature * constant

If you hold all the variables on the right side but increase the temperature, the volume also increases, and since density = mass / volume, when the volume increases, the density decreases. So an ideal gas under constant pressure becomes less dense as the temperature increases.

Anonymous 21/12/17(Fri)11:24 No. 17963 ID: 7f5b34

No. Hot air has more energy than cold air. And if we take Einstein's retarded equation E=MC^2, we know that energy is equals to mass.

And since density is the amount of mass per volume, then you'd have to take energy into account for the mass. And therefore, cold air is not denser than hot air.

Anonymous 22/03/24(Thu)16:29 No. 18205 ID: abdc5b

yes r3tard

Atmospheric absorption/scattering of sunlight Anonymous 18/07/27(Fri)04:35 No. 16685 ID: 953c1f [Reply]

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Hey, /sci/. I'm running a simulation of solar panel efficiency and I need some way to calculate energy production from the sun's position in the sky. For example, assuming a panel that is always pointer at the sun, when the sun is closer to the horizon the panel will generate less energy than when it's high in the sky.

I'm looking for something like f(x radians) = y W/m^2.


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Zaborro 22/03/02(Wed)11:22 No. 18170 ID: f9af09

No way you have the same working in Canada. We have sunny days only in summer, and we don't use it. Also it is very dark in our houses due to that. So I am sure it will not work.

Anonymous 22/03/02(Wed)12:51 No. 18172 ID: bf7eac

Sorry to hear that. Try moving to a less shitty latitude?

SecondHand 22/03/02(Wed)15:22 No. 18174 ID: 765a67

You could try to find a climatic compromise, for example. Suppose you get solar panels power supply in summer and traditional electricity in winter. How about that? As for house darkness you can get to newmarket window replacement https://thwindowsdoors.com/newmarket-window-replacement/ and change your small old windows to multiple new ones. This will attract some extra light, I assume.

Anonymous 22/02/20(Sun)15:32 No. 18139 ID: 583e76 [Reply]

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How do i learn 3d printing so i can make a few hundred thousand dollar every year?
I am trying to learn every and all about its software, hardware, and firmware troubleshooting but i dont know the whole spectrum of it... Im trying to master everything of it

Artificial sweeteners Anonymous 16/02/21(Sun)10:07 No. 16288 ID: f705da [Reply]

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Supposing a given artificial sweetener -- say, saccharine or aspartame -- was a carcinogen, what kind of cancer would it produce and by what mechanism?
If this question is too hypothetical to answer, by what mechanism would ingesting a non-toxic chemical cause cancer?

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sage sage 20/05/07(Thu)04:04 No. 16916 ID: 628398

> > Cancer is caused by some kind of mechanism damaging the DNA of cells on contact, producing a random mutation.
> That's like saying wounds are caused by insults.
No, it's more akin to saying wounds are caused by being clubbed.

> Cancer isn't just caused by mutagens for fucks sake, if that was the cause we would have cured cancer long ago.

Interesting conclusion, I was unaware we found a way to eliminate any possibility of mutations occurring.

Anonymous 22/02/03(Thu)03:16 No. 18094 ID: a5935d

Being caused by a virus isn't the same thing as being a virus.

The virus introduced mutations in the cells which - later - caused the cancer.

By inoculating against the virus you can prevent the mutations and therefore the cancer.

Anonymous 22/02/10(Thu)20:11 No. 18105 ID: be6f8f

I don't know if it's a virus, but some people's stupidity is definitely a disease, and we need some sterilization.

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