Stupid Question General #0

Is the amount of matter infinite within an expanding universe?

What's the application of the Bachet weighing problem?

6 months in and still don't know.

This one:

matematica.net/portal/e-books/Graham - Knuth - Patashnik - Concrete Mathematics.pdf

It's a math book for CS guys, or as I say, math for brainlets.

If this link don't work, try this one:
matematica.net/portal/e-books/Graham - Knuth - Patashnik - Concrete Mathematics.pdf

No, the space between matter just increases.

If the space between matter increased we would all be dead.

The amount of matter has little to do with the expansion. It could be infinite or finite. Expansion just means that within any finite region, the density of space is decreasing.

> If the space between matter increased we would all be dead.
> The density of space is decreasing

Choose one, friendo.

Should I remind you that density is a quotient between mass and volume?

What books do you recommend for GRE preparation?

Density is the degree of compactness of something. The density of *matter* is between mass and volume. Space does not have mass, fool.

Expansion does not necessarily increase the space between matter because gravity keeps mass in the same galaxy together.

Since a wave-function may have uncertain energy, does that mean that quantum mechanics does not conserve energy?

>Since a wave-function may have uncertain energy, does that mean that quantum mechanics does not conserve energy

No energy is always conserved in QM, in interactions the sate collapses so CoE holds.

Why, again, do we mandate that a function can have only one output per input? Does it give rise to paradoxes? Is it just axiomatic?

>Why, again, do we mandate that a function can have only one output per input?
because it's useful

>Does it give rise to paradoxes?
no

> Is it just axiomatic?
it's a definition

>because it's useful
Could you expound on this point, please?

>Could you expound on this point, please?
functions show up in lots of places

like polynomials, exponentials, logarithms, etc.

Not OP but it allows for exactness when working e.g. knowing someone is taking the +ve square root where the negative would change the form of the answer. You can have many valued functions but they are typically restricted to a range in which they are injective (one to one) e.g. in complex numbers you can restrict a function to an arbitrary sheaf when moving from around the complex plane.

If you've not done complex numbdrs then you can also think of the inverse trig functions which are many valued but we restrict the range we consider them to make it clear what values are being taken

You can surely see how it is more useful to define, for example, [math]\sqrt{x}[/math] as only the positive root, instead of [math]\pm \sqrt{x}[/math], so that when I ask my function what the square root of 4 is, I get 1 unambiguous answer back instead of 2 to decide from

Would making a thread about a possible experiment that is sort of /x/ tier still be Veeky Forums related? I invented a thing called sensomancy and now I want to make sure it's safe. I have test subjects but they seem content to join my discord and say next to nothing or /x/ stuff. I sort of regret recruiting from /x/ and it probably wasn't a good idea for several reasons.

Well fuck it then. I'm just going to make the thread. Nevermind, what a waste of time and energy.

...

It's too late. Would you be a willing test subject?

is that Japan?

Fag.

It's a legitimate experiment though. Plus I didn't wanna get banned.

Ok sci decide my grad school specialization between: applied electromagnetics/RF circuits, communications, optics/photonics, or signal+image processing/machine learning

Choose for me please i am too indecisive

is there a place that lists article titles from scientific journals?

Normally I'd pick a random option and add a persuasive argument to boot, despite being just a college dropout who's clearly incompetent, but I'll be nice this time.

Don't give away your power to choose. It's the only meaningful freedom you have, it's the only thing that makes life worthwhile.

Even by giving it away subtly by listening to other people's opinions you're setting yourself up. And you're doing directly.

EVERYBODY is an enemy. Don't add yourself to that list by asking others to decide for you.

What kind of math do I need to study to be able to git gud at 2D graphics programming drawing graphs with stuff like Cairo, Skia, etc?

WTF?!

How the fuck can it possibly be 3 if IT'S BEHIND THE FUCKING MIRROR FFS (that's what sketchmarks are for isn't it?)?!

do you not know how mirrors work m8?

Well tell me cause to me this makes no fucking sense

Is it possible to make a function where phase changes in matter are omits output? Also is it possible for there to be infibite phasechanges with respect to internal energy?

A small problem I've been working on for a week, because I'm stupid. Please tell me if you see any flaws in my reasoning.

You have n points on a plane. If you take any 3 of these, they are not aligned ; also two straight lines joining different points are never parallels.

You join all points to one another with straight lines.

In how many points do the lines intersect, except for the n points you have at the beginning ? (we will note this number [math]N[/math])
A bit of space if you want to try it yourself. Since you're not as brainlet as me, you'll figure it out faster.

My reasoning :
For the first points you need to draw [math](n-1)[/math] lines, for the second, [math](n-2)[/math], and so on.

Total number of lines :
[eqn](n-1) + (n-2) + \dots + 1 = \sum\limits_{i=1}^{(n-1)} i = \frac{n(n-1)}{2}[/eqn]

Let's call this number [math]n'[/math].
Since none of the lines are parallel, you have [math]\binom{2}{n'}[/math] points in which the lines intersect.
Out of these points, you have the [math]n[/math] points you had at the beginning. These points account for more than one intersection. Indeed, in each of these points you have [math](n-1)[/math] lines, the point "going to" the other [math](n-1)[/math] points.

So each of those original points account for [math]\binom{2}{n-1}[math] intersection points. We can now conclude that :

[eqn]N = \binom{2}{n'} - n*\binom{2}{n-1}[eqn]

... where [math]n' = \frac{n(n-1)}{2}[/math].

The tests I've done with 3 (N=0), 4 (N=3), 5 (N=15) seems to work.
What do you think ?

I fucked up the TeX.
[math]\binom{2}{n-1}[/math] intersection points. We can now conclude that : [eqn]N = \binom{2}{n'} - n*\binom{2}{n-1}[/eqn] ... where [math]n' = \frac{n(n-1)}{2}[/math]

Well if we can conclude that, then what's the problem?

I was wondering if I did any mistake. Apparently you didn't spot one, so that's all good.

How the fuck do we know what those angles in that small rectangle are equal to the left angle of the beige triangle? Makes no fucking sense.

nvm figured it out hahaha

PLS HELP

youre going to an all ages stem hall, what would you like to see?

brainstorming right now and Ive got:
>project classes (ham, robotics..)
>welding/workshops
>software/computer use
it's easy to engage the community for a community garden and hippie shit, but stem is a whole different thing

if you dont want to go in for a class, what would you have available other than free study space and coffee?
also, please note that this space will be available to you 24/7

thats just the definition. Its a definition that predates all the set theory and axiom stuff in the early 1900s.

you get one and only one output per input.

functions are super useful in computing. If you can verify that a process gets one output for each input, and that the output is consistent, you have a reliable process. unreliable processes cause bugs. The predicate function in logic has similar power. If a propositon is true, its always true, and its never true and false. All reasoning is functional.

A non-scientific here.

How can I take away the fear of death from a cosmic event? It really terrifies me.

It would be instantaneous and there is literally no conceivable way for us to avoid them. Comfort yourself in knowing that at best it will never happen, as it hasn't happened for thousands of years, and that at worst you won't even have time to realise it happened.

Software engineering or computer science?

Computer engineer student. I got A in every subject, but failed in maths this year (first year). Should i keep going on with the studies or just quit? I absolutely hate math and it's so hard for me to retain the anything about the subject.

How can I get my body to stop producing alcohol dehydrogenase? For... academic purposes.

It's a mirror on a plane, not in 3D space, the line from 3 to mirror is best reflected by the line A to mirror, not 1 to mirror as it may be in 3D space.

How can you be this much of a brainlet?

Is it like a general rule I've never heard of that the antiderivative of a function of x times a constant is its derivative over the constant? its derivative with respect to the x*constant I mean.

so like
∫f(cx)dx = f'(cx)/c

examples
∫cos(5x)dx = sin(5x)/5
∫e^(2x)dx = e^(2x) /2

totally didn't post this in the dead thread without realizing there was a new one ahhaha

you're kind of like me, I just got done with first year too in comp eng. my issue is that I'm really really not good at math even if I want to be, I just can't fucking do it and I know that I need to be good at it.

it's like, programming is what I want to make a living doing and I have the inability to do it because I'll never get a degree because I can't do math

>hate math
if you faggets like programming and are bad in math then you obviously dont get what computer scientits/engineers are doing you fricking pricks.
Edsger Dijkstra "programming for a computer scientist is like telescope for astronomy"

I get it it's about algorithms and proofs and graph theory and whatever the fuck

I'm saying I'll never be good at it

pose y= cx, then express the integral (with the change of domains) in terms of y and dy

it's just the definition. without that restriction, youd just have the definition of a relation.
as for the usefulness, and why it deserves its own definition, think of pretty much any theorem or definition in analysis. how would you define the integral of a "function" with 50 odd outputs?

how does university grades scaling work? I'm quite confused by the whole thing. An assessment in one of my classes has a massively low average but the professor says not worry because it will be scaled, which I don't understand what she means

depends on how autistic your teacher is

Can someone help me with figuring out on what should I put emphasis on during my math self study, if my points of interests are geometry and topology? I´m pretty okay with college calculus. Also, some textbook recommendations would be be very nice.

Get rich so you can AFFORD self study first.

Why is 11, 23, 5 and many others considered prime numbers when you can evenly divide them, for example: you can divide 11 by 2 for an answer of 5.5 and 5 for 2.5. Any answers?

WHAT THE FUCK FOR FUCK'S SAKE?!

What's your question.
T1 does equal T2 for the same string.

BUT IT'S EQUAL TO mg FFS. AND THEY ARE DIFFERENT.

[math]\mathbb{Z}/\mathbb{nZ}[/math]

Is it okay to pronounce this "mod n"?

Is a degree by the Open University taken seriously by research institutes, universities and employers or would a degree from Bumfuck State University be dozen times more worth?

no because it's not clear what set you're taking mod n

I'd call it either Z mod n Z or Z mod n, or in the case you're only looking at the group structure, calling it Cn (the cyclic group of order n)

If f(x,y) is an arbitrary binary primitive recursive function, is the unary function d(x) = f(x,x) also primitive recursive?

It feels like it should be but I can't see how to construct the defining equation while ensuring that it has the correct arity.
(I'm using the definition in logicmatters.net/resources/pdfs/gwt/GWT2f.pdf which essentially states that if f(x) and g(w,u,y) are primitive recursive then so is g(w,f(x),y).)

How the fuck do I get a matrix into (Reduced) Row-Echelon Form? Is it literally just guess and check or is there some trick that I'm missing?

I usually say "integers mod n" or "Z mod n" or "Z n" (per the common notation [math] \mathbb{Z}_n [/math])

>per the common notation

that notation gets confusing when n is prime

>Length contractions only contract in the direction of movement
>Lorentz transformations map circles/spheres to circles/spheres (Penrose 1958)

How the fuck? If a ship is moving inside a ring from a side to the opposite side, doesn't the ship see the radius in the direction of travel smaller than the orthogonal radius?

>tfw Veeky Forums will have generals now because of this shit
I don't want what happened to /v/ and /int/ to happen here.

What's the catch

How do I stop feeling emotion like Da Vinci?

/v/ and /int/ are usually more focused generals, this is an unfocused general which helps get rid of what would otherwise by hundreds of shit quality threads

Since a solenoid is pretty much an electrically controlled switch, you could in theory build a computer out of one, right? Like smaller ones than the one in a car.

Thinking about how to make computers from scratch, seems like a lot less material science required than vacuum tubes or silicone transistors

Veeky Forums I'll know you'll laugh at me but I need help. I can't for the like of me get excel to turn this into a scatter plot. What's wrong with the order of my data?

pls help

Do non-mathematicians fight about the order to list authors on their journal publications? Alphabetical seems so convenient in comparison

what was the most difficult concept you have covered in mathematics?

Im interestd in learning c++, I have very little knowledge of computer programming and have narrowed my choice of book to two.

The first is c++ primer, and the second is programming -- principles and practice using c++.

They're both advertised as beginner books but I', wondering if anyone here has a recommendation between the two.

the Picard-Lefschetz formula

still no idea what that was about

An image doesn't really exist. The object is at A and your looking into the mirror from wherever. Where does point A appear to be?

Pro-tip imagine that you don't know its a mirror and think its a window instead.

Google 'Gaussian Elimination'

Learn python

Xenotransfusion-enhancement
Would it be possible if we transfuse silberback gorrila blood in our bodies (let's say both subjects are highly compatible) to enchance in any way our bodies or mind? (long or short term)
[Memory transference in organ transplant recipients] maybe it could work the same way with blood on a smaller or different level.

Embolism due to blood clotting.

So there is no way to transfer blood (maybe low ammounts over a period of time or if that not works due to our based immune system a well calculated ammount) from a compatible silverback to a human?
>mfw I will never experience at least a glimpse of Grodd greatness

You have to match blood types even with human donors or the results will be fatal. For gorilla's who the fuck knows.

Even if you could you wouldn't absorb special powers. This isn't an anime.

Doing an exercise in a Serg Lang book, and I'm confused, even if it shows the answer I'm unable to tell how he did it.
>Show that if n is a positive integer at most equal to m, then

[eqn] \binom{m}{n}+ \binom{m}{n-1}= \binom{m+1}{n} [/eqn]

The answer is pic related. I get how he got the LCD and +m!n. The other parts of the answer is leaving me frustrated. How did he get (m-n+1) to be on top of the fraction? How in the world did he turn
>m!(m-n+1)+m!n
to
>m!(m+1)

pls help a brainlet out

>How did he get (m-n+1) to be on top of the fraction?
if you want to add fractions you need a common denominator, in this case it's n!(m-n+1)! as he wrote

so

m!/[n!(m-n)!] + m!/[(m-n+1)!(n-1)!]
= m!(m-n+1)/[n!(m-n+1)!] + m!*n/[(m-n+1)!n!]

as for the second part

m!(m-n+1)+m!n
= m![ (m-n+1)+n]
= m![m+1]