Archived threads in /sci/ - Science & Math - 647. page
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/v/irgin here, this may be strange and I'm not even sure it's topical for the board but I have a question.
I have a cousin who has just graduated from college and has become a physicist. He's fucking awesome so I want to get him a Christmas gift but I need opinions on what a physicist would like. Any ideas?
>>7640020
You should get him some dark matter.
>>7640020
>just graduated from college
Booze. He's a recently graduated student. Get him a normal gift like all people his age. You shouldn't buy gifts like books, hobbyshit or novelty items unless you know that person really really well. Get consumables for people who aren't your girlfriend/close friend.
...unless you can afford to buy him a cyclotron or something. Then get him that.
>>7640020
That's a tough question, anon, but I can tell you about something he'll definitely NOT like: popsci books. Non-science people will tend to think we'll love those while nothing could be further from the truth.
pic related, received it years ago, still haven't opened it
any cure for tinnitus incoming?
i cant sleep at this point.
listen to loud music breh
>>7640005
It's all in your head anon, just man up and stop listening to it.
set a radio to play whitenoise. it will mask the ringing.
Please, if someone can help me with this, i will be indebted to them. Im just..having way too much trouble with this problem. If someone can show the intermediate steps, it would be wildly appreciated (and what rules theyre using)
is that tan^-1 literally the reciproce of tan or the arctan
Okay mate it's pretty simple
you use the derivative formula for inverse tan and the chain rule
>>7639964
Are you asking why the derivative of arctan(f(x)) is
[math]
\frac{f'(x)}{1+(f(x))^2}
[/math]
or what?
Forget going to Mars. How long until someone builds a proper rotating wheel space station?
>>7639960
How long until your startup space station company gets off the ground?
>>7639960
why would anyone need that ?
>>7640396
>gets off the ground
8/10 made me giggle senpai
Hey /sci/,
I am getting rekt in linear algebra right now. Give me all of your resources and tell me what I should do.
>>7639885
Buy Quantum Mechanics by Cohen-Tannoudji.
Work through it until you understand it.
You are now a linear algebra master.
>>7639885
But seriously, I don't know what to tell you besides work through problems, watch lectures online, etc. There are plenty of youtube lectures and sometimes a second perspective is what helps someone learn. Linear algebra is immensely useful and applicable, so it's worth learning well if you plan to continue in STEM.
>>7639885
Holy shit, how?
eigenvalues?
You are fucked if you are struggling with simple matrices and row reduction
You should practice, look at cheat sheets/notes with examples
What is the point of mathematics?
What drives it forward? Why do people do it without a usage (in reality) for it?
>>7639875
>What is the point of mathematics?
it's a useful tool
>What drives it forward?
autism
>Why do people do it without a usage (in reality) for it?
autism
>>7639875
Why do people climb Mount Everest? Why do people get good at anything that doesn't have a practical application? It tickles their senses in a way they can't get otherwise.
>>7639896
I agree partly. Many problems that math asks weren't there in the first place. Someone had to think of them first. And while your sense can "be tickled" by solving problems i dont think that making up problems does so.
Well, is she? Or am I being closed-minded? The bacteria would need to be on a major vein and have genes to monitor glucose levels, right? Can all the required genes fit on an E. coli genome?
>>7639727
>Bacteria
>Cell
I believe you are the victim of trolling OP, lay off the drugs
>>7639727
>injecting insulin producing bacteria into the body with no way to regulate the insulin output
10/10 idea
what could possibly go wrong
brb gonna patent it before someone else does
I can see the problems but its nowhere near 'are you high' tier.
Is there an easy way to tell what's real gold and pearls?
You should be physically superior to pure gold
>>7639679
magnet
>>7639682
What?
What can be said of as the surface area of our field of vision? Isn't it a matter of fairly simplistic projective geometry to calculate this in exact m^2?
the surface area of the night sky
Idk m8
Can you really calculate the surface area when the cone of vision is constantly changing?
>>7639647
Then calculate surface areas of the different cones of vision and put them on a table. It would be interesting to know the max and min.
>Got a project the other day that was written like a dissertation.
>No example code, just paragraphs with minor examples of input/output.
>Normies in the class who slept through the required math courses BTFO and start to complain like mad.
>Professor don't give a fuck, TA don't give a fuck.
I take a few hours and recall my knowledge of math with a few searches on the subject and solve it without any code. Math is so damn good for CS,...
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Why do you study CS if you don't like math?
CS is basically applied math.
>>7639624
> feels good finding an algorithm before I even start coding
So you normally just type random lines and hope it works?
I have very little experience with Octave, I made a code to plot 4 lines on a graph, it worked, but when I changed the name of the file and tried to run it I got "error: 'filename' undefined near line 1 column 1"
any of you guys know how to fix this?
>expecting us to debug your code without posting said code
>>7639558
sorry, completly forgot:
clc;
x = -3.1415:0.1:3.1415; %limits for x coordinates
a = sin(x) %defining a
b = x %defining b
c = x - ((x.^2)/2) %defining c
d = x - ((x.^2)/2) + ((x.^4)/24) %defining d
plot (x,a, 'r')
hold on;
plot (x,b, 'b')
hold on;
plot (x,c, 'g')
hold on;
plot (x,d, 'y')
hold off;
legend ('y=sin(x)', 'y=x', 'x-x^2/2', 'x-x^2/2 + x^4/24')
>>7639587
how are you calling the file?
Dear /sci/,
Is it possible to launch a rocket from a balloon?
The launch components will get very cold, is there a way to keep the rocket in good condition for ignition and blastoff?
https://www.youtube.com/watch?v=fEJGI3NjJso
>>7639445
Sure, if you had a big enough balloon. But you' still have to get it up to orbital speed, which would take the same amount of fuel.
>>7639449
*you'd
>>7639445
We could use a hybrid airship as a reusable launch shuttle....
Put the platform between two airships as a pad
or four airships
o
0 X 0
o
X = Launch pad
All these scientists talk about how black holes are real.
Never seen a picture of one that wasn't CG.
>>7639438
6.28/10
Maybe you should perform your own experiments if you don't believe the work of others.
>>7639438
>Never seen a picture of something light can't escape from
/saged
Let's talk about reproduction.
Male walking leaves (the phylliidae family) will clean out the female's vagina before copulation. They do this to remove any possible spermatozoa from previous mates.
Some male humans go down on female humans. Is it possible that humans developed this sexual strategy for the same reasons that walking leaves did?
Are male pussy eaters betas AND cûcks?
>>7639369
Your last paragraph is wrong. It should have a negative, or start with Or.
>>7639369
Male pussy eaters ARE betas and keks.
Seriously, it is fucking disgusting.
But no, this is not our strategy to clean out sperm from other males. We grow large penises, way bigger than the vagina´s length, to do exactly that, remove the sperm from other males.
>>7639369
>Is it possible that humans developed this sexual strategy for the same reasons that walking leaves did?
No.
Next question.
Help me here, /sci/
I have 10k of database entries, with 20 integer atributes. I must classify each entry on one of n categories, based on their values.
Example: Entry A =[8,10,12,8] - Group x
Entry B =[5,0,20,25] - Group y
And so on...
I have the training values for each category, but I can't decide which technique to use - pretty newbie on this subject. Any sugestions?
>only 10k entries
Just try everything you can think of.
Reduce the number of cross-validation folds for those that take too long.
just use sort algorithms, many are already embeded in prog. languages.
if you have them in array of arrays form, just sort by the place or info in subarray (e.g. A[2]=12, following your example)
if you have them in struct form, you have already sorted atributes, just use sort and specify which atrivube in the sorting function
>>7639639
are you retarded
